2025 Atlantic Hurricane Season

GaWx · 2025-08-20T13:59:15Z

GaWx · 2025-08-20T14:06:50Z

As shown on the image below, one can see how rapidly 2025’s ACE has increased in relation to others since 1951: it’s now 16th highest of the last 75

BarryStantonGBP · 2025-08-20T14:10:54Z

3 minutes ago, GaWx said:

As shown on the image below, one can see how rapidly 2025’s ACE has increased in relation to others since 1951: it’s now 16th highest of the last 75

Now just wait for 99L to contribute nothing if he turns into fernand

WxWatcher007 · 2025-08-20T14:16:57Z

@GaWx where's your excellent piece on RONI and US landfalls? Do you have numbers for this season and where that stacks up with recent years? Working on my peak season forecast today and would like to include that in my final section.

BarryStantonGBP · 2025-08-20T14:24:22Z

7 minutes ago, WxWatcher007 said:

@GaWx where's your excellent piece on RONI and US landfalls? Do you have numbers for this season and where that stacks up with recent years? Working on my peak season forecast today and would like to include that in my final section.

I have 20-12-5, 190 ACE

WxWatcher007 · 2025-08-20T14:27:59Z

3 minutes ago, BarryStantonGBP said:

I have 20-12-5, 190 ACE

My annual forecast just looks at the peak, which is Aug 20-Oct 20. Hope to have it out later today.

BarryStantonGBP · 2025-08-20T14:41:35Z

13 minutes ago, WxWatcher007 said:

My annual forecast just looks at the peak, which is Aug 20-Oct 20. Hope to have it out later today.

I just feel major CONUS blows might be at the second half of the peak

GaWx · 2025-08-20T14:42:19Z

24 minutes ago, WxWatcher007 said:

@GaWx where's your excellent piece on RONI and US landfalls? Do you have numbers for this season and where that stacks up with recent years? Working on my peak season forecast today and would like to include that in my final section.

I’ll try to find it with a search on “RONI”.

GaWx · 2025-08-20T14:57:22Z

47 minutes ago, WxWatcher007 said:

@GaWx where's your excellent piece on RONI and US landfalls? Do you have numbers for this season and where that stacks up with recent years? Working on my peak season forecast today and would like to include that in my final section.

Thanks. I just found it. This is what I posted on 5/21/24 and thus this analysis doesn’t include what happened in 2024, a really bad year with it scoring 5G/0E. 2024’s ASO RONI was -0.75:

—————————

I just did an analysis of CONUS landfalls for RONI ASO -0.50 to -1.00 vs sub -1.00. E = east coast and G = Gulf coast including FL Keys; if storm landfalled on both as a H, I counted it as 1/2 E and 1/2 G (1995’s Erin and 2022’s Ian)

ASO RONI -0.50 to -1.00: every season at least 1
1954: 3 (3E)
1955: 2 (2E)
1964: 4 (2E, 2G)
1970: 1 (1G)
1983: 1 (1G)
1995: 2 (0.5E, 1.5G)
1999: 3 (1E, 2G)
2011: 1 (1E)
2017: 3 (3G)
2021: 2 (2G)
AVG: 2.20 (0.95E, 1.25G)

ASO RONI sub -1.00: less active avg despite 2020
1973: 0
1975: 1 (1G)
1988: 1 (1G)
1998: 3 (1E, 2G)
2007: 1 (1G)
2010: 0
2016: 2 (1E, 1G)
2020: 6 (1E, 5G)
2022: 2 (1.5E, 0.5G)
AVG: 1.78 (0.50E, 1.28G)

Analysis of ASO RONI wk vs mod+:
-sig. more CONUS H landfalls (100%/70% had 1+/2+)
-sig. more E coast landfalls (60%/30% had 1+/2+)
-slightly fewer G coast landfalls due to 2020 being active
-E being nearly as active as G for wk is relatively high for E
-2020 ASO is mod+ per RONI but is only wk per ONI

H tracks:
https://www.nhc.noaa.gov/data/

RONI: https://www.cpc.ncep.noaa.gov/data/indices/RONI.ascii.txt

WxWatcher007 · 2025-08-20T15:16:29Z

17 minutes ago, GaWx said:

Thanks. I just found it. This is what I posted on 5/21/24 and thus this analysis doesn’t include what happened in 2024, a really bad year with it scoring 5G. 2024’s ASO RONI was -0.75:

—————————

I just did an analysis of CONUS landfalls for RONI ASO -0.50 to -1.00 vs sub -1.00. E = east coast and G = Gulf coast including FL Keys; if storm landfalled on both as a H, I counted it as 1/2 E and 1/2 G (1995’s Erin and 2022’s Ian)

ASO RONI -0.50 to -1.00: every season at least 1
1954: 3 (3E)
1955: 2 (2E)
1964: 4 (2E, 2G)
1970: 1 (1G)
1983: 1 (1G)
1995: 2 (0.5E, 1.5G)
1999: 3 (1E, 2G)
2011: 1 (1E)
2017: 3 (3G)
2021: 2 (2G)
AVG: 2.20 (0.95E, 1.25G)

ASO RONI sub -1.00: less active avg despite 2020
1973: 0
1975: 1 (1G)
1988: 1 (1G)
1998: 3 (1E, 2G)
2007: 1 (1G)
2010: 0
2016: 2 (1E, 1G)
2020: 6 (1E, 5G)
2022: 2 (1.5E, 0.5G)
AVG: 1.78 (0.50E, 1.28G)

Analysis of ASO RONI wk vs mod+:
-sig. more CONUS H landfalls (100%/70% had 1+/2+)
-sig. more E coast landfalls (60%/30% had 1+/2+)
-slightly fewer G coast landfalls due to 2020 being active
-E being nearly as active as G for wk is relatively high for E
-2020 ASO is mod+ per RONI but is only wk per ONI

H tracks:
https://www.nhc.noaa.gov/data/

RONI: https://www.cpc.ncep.noaa.gov/data/indices/RONI.ascii.txt

Thanks. I wish I had the JJA number, so at least I had more confidence in inferring what the ASO number would be.

AStorms13 · 2025-08-20T21:03:40Z

6 hours ago, GaWx said:

As shown on the image below, one can see how rapidly 2025’s ACE has increased in relation to others since 1951: it’s now 16th highest of the last 75

Things can change very quickly. People like to jump on current sentiment and extend it over the entire upcoming season. It is also pretty scary seeing how fast some of these storms have been escalating these past few years.

cptcatz · 2025-08-20T21:08:34Z

1 minute ago, AStorms13 said:

Things can change very quickly. People like to jump on current sentiment and extend it over the entire upcoming season. It is also pretty scary seeing how fast some of these storms have been escalating these past few years.

Yeah, last year Beryl skyrocketed ACE in early July but then it pretty much flatlined until late September when Helene showed up.

BarryStantonGBP · 2025-08-20T21:14:36Z

LazzaWX said this on Storm2k, what are your thoughts?

LarryWx: S2K Supporter; Posts: 6467; Joined: Sun Sep 07, 2003 2:04 pm; Location: GA

Re: 2025 Indicators: SST's, MSLP, Shear, SAL, Steering, Instability (Day 16+ Climate Models)

#525 by LarryWx » Wed Aug 20, 2025 12:36 pm

Based on the ensembles and European Weeklies, I wouldn’t be surprised if it’s quiet for a couple of weeks starting August 24th. If so, this could somewhat resemble 2024’s very quiet 19 day period (late August through early Sept.). If so, I’d then be expecting an active 2nd half of Sept. and probably into early Oct. (also similar to 2024 ).

Other opinions?

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The posts in this forum are NOT official forecasts and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

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Re: 2025 Indicators: SST's, MSLP, Shear, SAL, Steering, Instability (Day 16+ Climate Models)

#526 by LarryWx » Wed Aug 20, 2025 3:35 pm

The brand new Euro Weeklies continue with yesterday’s run’s idea of a more active 3rd week of Sept than the first half, somewhat resembling 2024 especially considering the possible relative quiet for next week based on quiet ensembles:

Here are today’s EW ACE forecasts:
8/25-31: 9-10
9/1-7: 4
9/8-14: 10-11
9/15-21: 13-15

Edit: Keep in mind that the EW did well last year with the lull.

GaWx · 2025-08-20T21:24:14Z

4 minutes ago, BarryStantonGBP said:

LazzaWX said this on Storm2k, what are your thoughts?

LarryWx

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Posts: 6467

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Location: GA

Re: 2025 Indicators: SST's, MSLP, Shear, SAL, Steering, Instability (Day 16+ Climate Models)

#525 by LarryWx » Wed Aug 20, 2025 12:36 pm

Based on the ensembles and European Weeklies, I wouldn’t be surprised if it’s quiet for a couple of weeks starting August 24th. If so, this could somewhat resemble 2024’s very quiet 19 day period (late August through early Sept.). If so, I’d then be expecting an active 2nd half of Sept. and probably into early Oct. (also similar to 2024 ).

Other opinions?

3 likes

Personal Forecast Disclaimer:
The posts in this forum are NOT official forecasts and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

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LarryWx S2K Supporter
Posts: 6467 Joined: Sun Sep 07, 2003 2:04 pm Location: GA

Re: 2025 Indicators: SST's, MSLP, Shear, SAL, Steering, Instability (Day 16+ Climate Models)

#526 by LarryWx » Wed Aug 20, 2025 3:35 pm

The brand new Euro Weeklies continue with yesterday’s run’s idea of a more active 3rd week of Sept than the first half, somewhat resembling 2024 especially considering the possible relative quiet for next week based on quiet ensembles:

Here are today’s EW ACE forecasts:
8/25-31: 9-10
9/1-7: 4
9/8-14: 10-11
9/15-21: 13-15

Edit: Keep in mind that the EW did well last year with the lull.

Barry, I agree because that’s me.

BarryStantonGBP · 2025-08-20T21:31:20Z

6 minutes ago, GaWx said:

Barry, I agree because that’s me.

OI LAZZA

NICE ONE LAD

Do you rule out any quick spin ups in the GOM during the "inactive" period that's set to favour the EPAC?

BarryStantonGBP · 2025-08-20T22:01:17Z

Sorry Fernand, it's Juliette's turn

BarryStantonGBP · 2025-08-20T22:07:01Z

WxWatcher007 · 2025-08-21T01:32:32Z

Alright, here it is.

13 minutes ago, WxWatcher007 said:

August 20 is here, which means the bell has been rung.

WxWatcher007 2025 Atlantic Peak Season Forecast

As a major hurricane churns off the east coast, we have reached the start of the peak of the hurricane season. So far, we've had 5 named storms, 1 hurricane, and 1 major...and one category five hurricane.

The start of the season has been quiet, and while the general thought has remained that the season overall is likely to finish above average, my forecast looks at prime time. The background state of this season, unlike past years, has been quite hostile across the basin, but beneath the surface, conditions have been lining up for another active backloaded season.

I define peak season as August 20-October 20, and this forecast covers that period. This is my 7th year writing such a forecast, and my record has been very good on balance, with the exception of one season.

Seasonal Grades

2019 Grade: B+
2020 Grade: A-
2021 Grade: C
2022 Grade: B
2023 Grade: A
2024 Grade: B

Last year, we had a historically quiet first half of the peak season, with Ernesto forming on August 12th and no named system forming until Francine on September 9th. From there, all hell broke loose, with six additional hurricanes, three of them major, and two, Helene and Milton, being historic.

This season it has been a struggle to get anything to survive in the basin, until Erin of course. The coming weeks likely bring a quiet period that may very well be reminiscent of last season. Then, the lid comes off.

ACE will flatline for a bit after Erin and the possible central Atlantic wave, but I think this year is shaping up to be another highly active second half peak.

Peak Season Forecast (Aug 20-Oct 20)
Named Storms: 10
Hurricanes: 6
Major Hurricanes: 3

As a reminder a typical season finishes at 14/7/3

Here are the major factors contributing to my forecast this season.

1. ENSO

We start here and you always should. This year, ENSO favors activity. We are under a La Nina watch, so this is not the same kind of highly favorable regime that we had during our recent Nina stretch, but ENSO neutral conditions can still be very favorable.

The 3.4 region has been cool neutral through the spring and summer, and if anything has cooled recently. This has big implications for the Atlantic basin, as a cool neutral ENSO brings many of the same impacts as a Nina, most notably, lower wind shear.

(Image courtesy of Michael Lowry. Note the tracks as well)

A cool neutral ENSO should bring us lower than normal wind shear in much of the basin during the peak, giving me confidence that we get a substantial number of hurricanes and major hurricanes, should they overcome some of the other obstacles in the basin.

2. West African Monsoon

The WAM is a tricky beast. Last year, I think it running a bit hot led to some of the waves coming off Africa far too north, enhancing major stability issues and the SAL intrusions we saw in the tropical Atlantic.

It was only in the last week or so that we started to see the wave train go, but it had a very different result from last year, with less SAL kicked up, though there has certainly been plenty of SAL out there in the basin. As the image below suggests, we will see above average precipitation across north Africa, which essentially serves as a proxy for the strength and persistence of the wave train.

Shout out to CSU for putting me onto this longer range product.

3. Wind Shear

This is a huge piece of what's going to determine the outcome of the peak forecast. As stated earlier, a non-El Nino season tends to have much less shear across the basin, and with a cool neutral ENSO it is highly likely that shear is less of an issue off the U.S. east coast and into the Caribbean. This has already proven to be the case as summer advances toward fall in the Caribbean and off the east coast. The tropical Atlantic, which I continue to believe will not be nearly as conducive for activity as it could be, has been the opposite.

Although it is likely to be quiet during this period, you can see how deep layer shear becomes anomalously low across much of the basin as we move into the September high peak. I don't see a ton of anticyclonic wave breaking during the peak which would gut activity from the basin, but as we know, whether a wave develops and how much depends on in-situ shear often. Just knowing that the background state for shear will be favorable is more than enough for August 20.

4. SST & OHC

I think the defining feature of this season will be the activity being concentrated in the SW Atlantic. Perhaps fortunately for my forecast, Erin kind of provides proof of concept. Erin came off the African coast as a robust wave, but ran into SAL to its north. Although that stunted its development for a few days, a warmer western Atlantic, low shear, and higher OHC led to explosive development.

Sea surface temperature anomalies and ocean heat content were two major concerns I had going into this season, and for a while, it looked like it would greatly reduce potential. Erin's wake notwithstanding I think SSTs and OHC are now some of the chief reasons why I expect another high end peak.

This analysis from Andy Hazelton sealed it for me.

The pattern the last few years has remained fairly consistent in this forecast. The best conditions are west of about 60W, with higher OHC. This year we have SST anomalies in the mix, with the highest anomalies in the basin in record territory in the western Atlantic.

Here was 2024 for reference.

What a difference a year makes.

Erin's wake will likely recover, especially considering how high OHC levels are in the southwest Atlantic. While the tropical Atlantic SSTs are running behind other recent historic years, that is not the case where it matters for impacts in our neck of the woods, with the Gulf and Caribbean untapped, and the SW Atlantic warmer than past years.

OHC however, is where the real concern for higher end activity lies. Much like SSTs, in the tropical Atlantic the warmth is lower than in the Gulf and Caribbean. But look at the western Atlantic and the east coast in particular.

It is the SW Atlantic where anomalies show that even in Erin's wake, there is plenty of heat there for any coastal storm that is close enough to take advantage of it.

The bottom line is that the SST and OHC orientation is such that a high end peak is possible, especially in the western Atlantic, Caribbean, and Gulf.

5. MJO & CCKW

The MJO and CCKWs that triggered the wave train have passed, and as we enter the peak of the season we are flipping to an unfavorable state in the basin. This alone should suppress activity as we are only at the beginning of the ramp up period for the peak. How long this lasts is TBD, and we have to keep in mind that while it may suppress MDR activity there are certainly short fuse named storms that could happen in a more favorable thermodynamic environment in the western Atlantic, western Caribbean, and Gulf.

That said, things are likely to get quiet in terms of numbers, but the change is likely temporary. The MJO is expected to return on the second half of the peak. We saw last year that you don't need a lot of time to get the Atlantic to boil once the lid comes off. As the EPS suggests, we could start seeing favorable conditions return even earlier in the peak period, but I think a conservative expectation of things to heat up with the MJO after the 20th is the best route. That would make the September 20-October 20 period most active.

6. Stability, Dry Air, and SAL

The final factor is perhaps the biggest in the early part of the forecast, and less so in the latter half as climatology takes over. It has actually been a lower end year for SAL in the basin, but once again the timing of SAL intrusions and peak climatology for SAL suppressed activity until Erin. Compare this to 2023 and 2024. Images courtesy of Michael Lowry.

The recent wave train has helped clear the way to an extent for future waves, and although I don't expect a lot of development from the MDR in the coming two to three weeks, even waves that do not develop have the benefit of moistening the environment, just as our recent failed invest did, to pave the way for higher end activity. Even though there is SAL in the basin, it's not nearly as bad as it has been in recent years at this time in the tropical Atlantic.

But SAL is only one part of this equation. We also have to look at base stability, which continues to be an issue in the eastern MDR. Vertical instability has been below normal for years in the eastern Atlantic, with instability improving the further west you go. This, like other years, is one of the biggest factors for believing the western Atlantic will be the hot spot.

The east coast and Gulf have had extremely high levels of instability, which likely contributed to some of our early invests.

Instability rises dramatically in September and October in the tropical Atlantic as climatology shifts and SAL reaches its nadir. I see no reason to question this again in 2025. As we saw in recent years, even if late August and early September are quiet due to a combination of SAL and stability, that lid still gets ripped off by late September provided an active wave train can moisten the environment.

Overall

It may not start out hot (though I would watch the area in the central Atlantic for becoming the first NS/H for the peak period), but I expect another high end and backloaded peak season. The biggest piece of the puzzle--what the MDR SST and OHC profile would evolve into--has been answered, and it is high end again. None of this is normal, but that's the state that we have been in since 2017 in the Atlantic. An unfavorable MJO and declining climatology for SAL and stability in the eastern MDR will likely stunt high quantity activity through about mid-September, but things will likely reverse in a big way for the last 4-5 weeks of the peak season period.

Unlike last season, I do not expect a lot of activity late into the season, like we saw last year in November. I think a less robust WAM will produce less waves by then that are able to cross the Atlantic, and a less favorable MJO by the time we get to very late October.

Landfall Odds

I think a combination of ENSO, the active WAM, wind shear, instability, and SST/OHC will make the southwest Atlantic the hot spot this year. This is consistent with historical trends of a wet Sahel and moving from ENSO regimes. Images courtesy of Eric Webb.

Note that the Gulf still gets storms, but I think this is a quieter year for that region. I think given what we've seen so far, and some of the long range steering pattern guidance (which is to be taken with a grain of salt), the central and eastern Caribbean, Bermuda, east coast, and Atlantic Canada--which is on a historic run of tropical cyclone landfalls--are most likely to be under the gun this season.

I think there are a lot of recurves this season, but several threats for the region I highlighted. I think there is at least one east coast hurricane strike this year, and that we continue our streak of major hurricane strikes on the U.S. coastline.

Whether that means the east coast breaks its 21-year streak of no major hurricane landfalls, or New England breaks its 34-year streak of no hurricane landfalls (though I think the odd of this happening are substantially lower than the former) remains to be seen.

If there is a New England strike, it would be something that comes from the Caribbean or a short fuse system in the southwest Atlantic, not a long track system. Ironically, the opposite would be true for a southeast coast--not including far eastern NC, which often gets scraped in a strike that ends in a landfall further north--with something developing east of the Antilles and getting trapped under a subtropical ridge.

Thank you for reading.