donsutherland1

The most extreme March heatwave on record in the United States is now concluding. Additional monthly records were set today. Below is a selection of March records that matched or beat April records during the unprecedented heatwave.

After some overnight showers and perhaps a thundershower, it will turn somewhat cooler tomorrow with highs reaching the lower and middle 50s. The weekend will start on a cold note with the low temperature likely near or even somewhat below freezing in New York City and high temperatures in the middle 40s on Saturday. Sunday will become somewhat milder. The ENSO Region 1+2 anomaly was +1.6°C and the Region 3.4 anomaly was 0.0°C for the week centered around March 18. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +1.15°C and the ENSO Region 3.4 anomaly has averaged -0.08°C. Neutral ENSO conditions will continue through at least mid-spring. The SOI was -9.10 today. The preliminary Arctic Oscillation (AO) was +2.529 today. Based on sensitivity analysis applied to the latest guidance, there is an implied near 100% probability that New York City will have a warmer than normal March (1991-2020 normal). March will likely finish with a mean temperature near 45.8° (3.0° above normal). Supplemental Information: The projected mean would be 3.3° above the 1981-2010 normal monthly value.

And the updated chart:

I'd want to continue to play in his memory. Like you, I don't know how he calculated his curve.

Unseasonably warm air will briefly move into the region tomorrow. Hights will top out in the upper 60s and lower 70s. Friday will be somewhat cooler with highs reaching the middle 50s. Another cold front could cross the region on tomorrow night or Friday. The front will bring a few showers or thundershowers. The weekend will start on a cold note with the low temperature likely near or even somewhat below freezing in New York City and high temperatures in the middle 40s on Saturday. Sunday will become somewhat milder. The ENSO Region 1+2 anomaly was +1.6°C and the Region 3.4 anomaly was 0.0°C for the week centered around March 18. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +1.15°C and the ENSO Region 3.4 anomaly has averaged -0.08°C. Neutral ENSO conditions will continue through at least mid-spring. The SOI was -9.62 today. The preliminary Arctic Oscillation (AO) was +2.585 today. Based on sensitivity analysis applied to the latest guidance, there is an implied near 100% probability that New York City will have a warmer than normal March (1991-2020 normal). March will likely finish with a mean temperature near 45.5° (2.7° above normal). Supplemental Information: The projected mean would be 3.0° above the 1981-2010 normal monthly value.

Phoenix: March 1-24, 2026 vs. its historical record.

To illustrate the extreme nature of the ongoing heatwave in Phoenix, there were six dates since 1980 when the daily record was broken by 8F or more. Four were: 3/19/2026, 3/20/2026, 3/21/2026, 3/22/2026. The others: 9/28/2024, 10/6/2024.

Phoenix has now reached 100° for the seventh consecutive day. That surpasses the April record of six consecutive days from April 25-30, 1992. Over the past seven days (March 18-24), Phoenix has had a mean high temperature of 102.7°. That tops the seven-day record for April of 101.7° that was set during April 24-30, 1992.

Milder air will return for the remainder of the work week. The temperature will return to the lower and perhaps middle 50s through Friday. Another cold front could cross the region on Friday. The weekend will start on a cold note with the low temperature likely near or even somewhat below freezing in New York City and high temperatures in the middle 40s on Saturday. Sunday will become somewhat milder. The ENSO Region 1+2 anomaly was +1.6°C and the Region 3.4 anomaly was 0.0°C for the week centered around March 18. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +1.15°C and the ENSO Region 3.4 anomaly has averaged -0.08°C. Neutral ENSO conditions will continue through at least mid-spring. The SOI was +0.86 today. The preliminary Arctic Oscillation (AO) was +2.779 today. Based on sensitivity analysis applied to the latest guidance, there is an implied 99% probability that New York City will have a warmer than normal March (1991-2020 normal). March will likely finish with a mean temperature near 45.4° (2.6° above normal). Supplemental Information: The projected mean would be 2.9° above the 1981-2010 normal monthly value.

Here's Yellowknife's coldest March: https://climate.weather.gc.ca/climate_data/monthly_data_e.html?hlyRange=1953-01-01|2013-01-17&dlyRange=1942-07-01|2013-01-16&mlyRange=1942-01-01|2007-11-01&climate_id=2204100&Prov=NT&urlExtension=_e.html&searchType=stnName&optLimit=yearRange&StartYear=1840&EndYear=2026&selRowPerPage=25&Line=0&searchMethod=contains&Month=3&Day=23&txtStationName=yellowknife&timeframe=3&Year=1964 That translates into a monthly mean temperature of -17.6°F.

I believe that's the ranking, not the number of days.

Sixth consecutive day, which ties the April record from April 25-30, 1992.

Cooler air will move into the region overnight. As a result, temperatures will start out in the lower and middle 30s tomorrow morning before topping out in the upper 40s in New York City. Some upper 20s are possible outside the City. Readings will then return to the lower and perhaps middle 50s by midweek. Another cold front could cross the region on Friday. The ENSO Region 1+2 anomaly was +1.6°C and the Region 3.4 anomaly was 0.0°C for the week centered around March 18. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +1.15°C and the ENSO Region 3.4 anomaly has averaged -0.08°C. Neutral ENSO conditions will continue through at least mid-spring. The SOI was +18.28 today. The preliminary Arctic Oscillation (AO) was +2.069 today. Based on sensitivity analysis applied to the latest guidance, there is an implied 96% probability that New York City will have a warmer than normal March (1991-2020 normal). March will likely finish with a mean temperature near 45.2° (2.4° above normal). Supplemental Information: The projected mean would be 2.7° above the 1981-2010 normal monthly value.

Yes, an NAO+ is correlated with warmth in the SW. In fact, it is correlated with almost CONUS-wide warmth.

I didn't say "never" in the Earth's history. Almost certainly there were comparable or even more severe heatwaves during the mid-Pliocene, Eocene Thermal Maximum, etc. I stated, that the current March heatwave "is the most severe heatwave Phoenix has experienced in the period where records exist (even prior to the daily period of record that begins in August 1895) during March." It is. There's no credible information to suggest otherwise.

It does. But it's worth noting that the Dust Bowl was not a solely natural pattern-driven or cyclical event. Human factors helped create the conditions that made the Dust Bowl possible. The underlying drought was real and it was likely sparked by internal variability. However, poor land management made it far worse than it would otherwise have been. Extensive plowing of native grasslands and exposed topsoil left the land highly vulnerable to wind erosion once rainfall diminished turning a dry period into a catastrophe. Overall, the Dust Bowl is a powerful analog for a climate-change-driven aridification scenario because it shows how prolonged drought, extreme heat, and depleted soil moisture can combine into a self-reinforcing phenomenon. One is already witnessing drought-heat feedback in the Southwest, which is likely in the early stages of aridification, as forecast on the climate models.

Yes. This is a far more prolonged and more severe heatwave. Indeed, the five-day average high in Phoenix (103.8°) is above the April record five-day average of 103.0° from April 26-30, 1992. Nothing comes close to comparing to this March heatwave in the Southwest.

A few showers, thundershowers, and periods of rain are likely tonight into tomorrow. A somewhat cooler air mass will confine temperatures to the upper 40s in New York City tomorrow and Tuesday. Readings will then return to the lower and perhaps middle 50s by midweek. Another cold front could cross the region on Friday. The ENSO Region 1+2 anomaly was +1.5°C and the Region 3.4 anomaly was 0.0°C for the week centered around March 11. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.98°C and the ENSO Region 3.4 anomaly has averaged -0.15°C. Neutral ENSO conditions will continue through at least mid-spring. The SOI was +4.02 today. The preliminary Arctic Oscillation (AO) was +2.064 today. Based on sensitivity analysis applied to the latest guidance, there is an implied 94% probability that New York City will have a warmer than normal March (1991-2020 normal). March will likely finish with a mean temperature near 45.2° (2.4° above normal). Supplemental Information: The projected mean would be 2.7° above the 1981-2010 normal monthly value.

That's not the issue. His inaccurate claims concerning Phoenix in 1879 is the issue.

He's not a practicing meteorologist. He works for an organization that largely rejects AGW. Regardless of his position and employer, he should post accurate data. It's difficult to know why he would post information regarding Phoenix that is so obviously wrong (112° in March, 100° on March 3, and 7 100° days in March during 1879), especially as Phoenix is a high-profile city and, by its nature, has resources that can be found through research.

No. He blocked me when I corrected him in the past for misrepresenting data and provided links to the actual data. I did post the correct MWR data on Twitter/X in a thread in which he's copied.

Yes. that's correct regarding San Diego and Los Angeles. That's why I referred to it as a "localized heat event in southern California." Some heat came eastward into a portion of Arizona (Yuma's 100° reading), but this wasn't the kind of widespread heatwave like the ongoing on. It was nowhere near as intense as the ongoing one. Unfortunately, the maps have a a nine-hour gap between observations and there isn't a larger set of observations. I suspect that the offshore winds winds seen north of Los Angeles at the 4:35 am PDT observation sank south after that observation. The wind then turned onshore shortly before the 1:35 pm PDT observation, as the temperature was still 97° in the Los Angeles area.

As was the case last year when Phoenix reached an August monthly record high of 118°, an ignorant handful are attempting to dismiss the magnitude of the ongoing unprecedented March heatwave. In this case, the effort is to transform what was very likely a localized heat event in southern California due to possible offshore winds into an epic regionwide heat event that surpassed the ongoing heat event that has toppled March and April records in many locations in the West. The above post also applies projection, accusing the news media, of not doing "much digging." In fact, the post demonstrates dismal research skills. The question concerns whether Phoenix ever reached 112° in March during 1879. That heatwave was likely referenced, because Phoenix's daily records go back to August 1895. Thus, the underlying assumption was that one could not credibly question the claim. That's not true. Several approaches apply. 1) Is there any credible data for Phoenix from March 1879? Yes. Monthly Weather Review published monthly maximum and minimum temperatures for select locations. Below is the Monthly Weather Review report for March 1879. I highlighted Phoenix and Tucson, as one can make a comparison to the current heatwave. The monthly high temperatures for Phoenix and Tucson during the current heatwave are 105° and 102° respectively, vs. the 94° and 90° in March 1879. 2) If there were no credible data (not the case here), are there any reliable records from this period in the relevant area? Yes. Yuma's climate record goes back to January 1878. Yuma's monthly maximum temperature for March 1879 was 100° on March 29, 1879. Yuma's highs are typically above those of Phoenix. For example in the current heatwave, Yuma had a peak high of 109° vs. Phoenix's 105°. One could also construct a regression equation to estimate Phoenix's high based on Yuma's data. Since one is dealing with pre-urban Phoenix, I chose the earliest 30-year period of each site's overlapping record (March 1896-March 1935). The regression equation was (0.908 *Yuma's Maximum) +3.152. The standard error was 3.33°. The coefficient of determination was 0.833. So, what happens when one calculates the estimated highs for Phoenix based on the Yuma's March 3 high of 81° and its March 29 high of 100°. The end result is an expected high of 77° (76.7°) on March 3 and a high of 94° (94.0°) on March 29. The statistical data reveal that there was virtually no chance that Phoenix was 112° during March 1879. In fact, the statistical data matches the actual monthly high. Major Findings: Note: Actual data is the Monthly Weather Review monthly maximum temperatures for Phoenix and Tucson and daily data from Yuma's climate record. What happened? More than likely Martz was using data from a thermometer that was exposed to direct sunshine. Amateurs accept such data at face value. They have little understanding of issues that could compromise the data or little understanding about conducting research. Those with motivated reasoning embrace such data when it confirms their biases. Researchers ask questions concerning whether reliable data exists for the specific location, whether reliable data exists for nearby locations, etc. If reliable data is present for nearby locations, but not the specific location, they construct models based on the relationship of those nearby locations and the specific location in question. Afterward, they run those models and make estimates. I used statistical modeling just to illustrate how such models can be quite accurate. There was actual data (Monthly Weather Review). Overall Conclusion: The March 2026 heatwave is the most severe heatwave Phoenix has experienced in the period where records exist (even prior to the daily period of record that begins in August 1895) during March. There has been no remotely comparable past March heat event to the ongoing one affecting Phoenix and the Southwest.

The previous earliest 3 consecutive day stretch of 105 days was May 2-4, 1947.

The temperature will rise into the lower to perhaps middle 60s during on Sunday. A few showers and thundershowers are likely late tomorrow into early Monday. A somewhat cooler air mass will likely arrive early next week. Monday and Tuesday will see temperatures topping out in the upper 40s to near 50° in New York City. Readings will return to the lower and perhaps middle 50s by midweek. The ENSO Region 1+2 anomaly was +1.5°C and the Region 3.4 anomaly was 0.0°C for the week centered around March 11. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.98°C and the ENSO Region 3.4 anomaly has averaged -0.15°C. Neutral ENSO conditions will continue through at least mid-spring. The SOI was -1.25 today. The preliminary Arctic Oscillation (AO) was +2.149 today. Based on sensitivity analysis applied to the latest guidance, there is an implied 87% probability that New York City will have a warmer than normal March (1991-2020 normal). March will likely finish with a mean temperature near 44.9° (2.1° above normal). Supplemental Information: The projected mean would be 2.4° above the 1981-2010 normal monthly value.