TheClimateChanger

Wow, 112F heat index at Southwest Michigan Regional, and they are under a heat advisory. That should be a climate emergency, not a heat advisory.

The current temperature at MKE is 98F. If it holds or increases in the next hour, it would be the highest 2 pm reading on record dating back to 1947 in the month of August. The current record is 98F, from August 16, 1988, and earlier dates. Not sure of the earlier date(s), but I believe August 1, 1988 is one.

I will say in the interest of fairness, one thing that does call into question the NWS's claim is that they are comparing 5-minute data to hourly observations. To be fair, they probably should limit the comparison to top of the hour data since we don't have 5-minute data for most of that time frame.

Yeah, there's a massive infestation in western Pennsylvania.

Wow, historic. This may very well be the highest RELIABLE heat index reading on record. As noted by Tom Karl & Richard Knight, in their 1996 paper examining the role of climate change on the 1995 heat wave, the HO-83 hygrothermometer had a warm bias of at least 0.5C. This was one of the reasons they were unable to confirm any impact from climate change on the occurrence of extreme heat episodes. However, other research has found warm biases of as much as 2-3C on sunny, light wind days. The design allowed warmed air to recirculate into the housing for the sensor. I hate to bring this up since I was accused of trolling the 1988 drought thread, but ironically it was noted climate denier, Steve McIntyre, who first brought this to my attention.

Might only be a couple days in Chicagoland, but parts of the region are already onto day 4 of extreme heat and humidity.

HX of 112F at MDW and ORD, as of noon local time. New August record for that hour, in the IEM dataset. Also, the highest of any date after August 1st for that hour. Tied highest on record for any hour post 8/15 at MDW.

Sioux City, Iowa breaking heat index and dewpoint records left and right in recent days. The heat index of 122F from Monday was the highest of any hour on record back to 1942.

Tied the warmest low temperature on record (of any date in the year!) at Sioux Falls yesterday. Records date to 1893!

Here is MKE - already starting to see 2023 make the list. The 103F heat index at 10 am today ties highest on record for that hour in the month of August, dating back to 1947.

August hourly heat index records at ORD (1946-present) and MDW (1948-present), per Iowa Environmental Mesonet data plotter (see below). Should be close to some of these numbers the next couple of days, although that 117F from 8/1/1953 is probably out of reach. ORD MDW

What's the wet bulb temperature looking like? I'm beginning to think large portions of the country will be uninhabitable during summer by later this century due to increasing heat and humidity. I've heard wet bulbs around 91-95F (33-35C) are around the limit of human survivability. I mean sure you can escape inside to the air conditioning (as long as it is working), but who is going to live in a place where an extended power outage in the summertime is potentially fatal?

The readings are converted from Celsius, but the 5 minute obs convert from rounded Celsius values. So the 98.6 is 37C, but the actual observed high was less than 36.9C.

Heat index reached 117F at Omaha’s Eppley Field at 7 pm, tying the monthly record also set at 7 pm on August 1, 2011. Point-click for OMA has 103 and 101 next two days. If dewpoints stay as elevated as they have been the past couple days, could see 120F. Des Moines peaked at 113F, one shy of the monthly record from August 15, 1988. And that goes all the way back to 1936. Point-click has temps of 101 & 98 at DSM next two days. Today’s high was 96F. Just multiple days of a record-breaking combination of heat and humidity for the month of August. The duration has to be a concern, especially for any unhoused persons.

I remember the 2001 heat episode. Killed Kory Stringer at Vikings practice.

Looks like the 114F heat index was a new monthly record at MSP airport.

Just 2023 doing 2023 things.

Interesting to see 1936 with so few heat index records at Des Moines, despite the extreme temperatures. Looking at the data, looks like it had the fewest hours of dewpoints at or above 65F of any year. Some of the years in the late 1960s to mid 1970s might be lower, but they are shaded in blue indicating more than 20% of the data is missing. The only other comparable year is 2009. Also, one of the most hours below 60F, behind only 1944, 2009 & 2014. Second most hours below 50F, behind only 1940. And heck there were more of those in July 1936 than there have been in the entire past decade. Also the only year to accrue any hours with a dewpoint below 40F - 8 of those to be exact.

Here are the August numbers for DSM and OMA: Des Moines - the 112F reading was the highest for the 3 o'clock hour. All-time record for the month is 114F, set on August 15, 1988, at 2pm and 4pm. A number of hourly maximum apparent temperatures were set just last year on the 3rd and 7th of the month. Omaha - easily the most impressive August heat on record, dating back to at least 1948. The 116F reading at 6 pm yesterday was one shy of the monthly record set on August 1, 2011, at 7 pm.

Here are some numbers to beat for the maximum observed heat index for each hour. Top is Omaha, and bottom is Des Moines. As you can see, the heat index of 116F at Omaha at 6 pm yesterday set a new record for that hour, and was just 4F below the all-time record of 120F, set on July 14, 1988 at 5 pm. The record heat index at Des Moines is 122F, on July 25, 1936, at 5 pm. No all-time hourly maxima have been set during the current heat wave so far.

These threaded records are so dumb for Pittsburgh, especially in the summer, when the variability is at a minimum. Summer to date is 34th warmest (of 71 years) at KPIT, so just above the median of all years observed at the International Airport. But in the threaded record, it is 43rd coldest (of 149 years) (or 102nd warmest, as there were a lot of years tied with it). Adding those 78 years, the ranking drops 68 places! In other words, 68 of the 78 years in the threaded record before PIT existed (from 1875-1952) were warmer than this summer. In the threaded record, it will look like a relatively cool summer at PIT. But in reality, it's actually slightly warmer than the long-term median when you correct for location & elevation of the airport.

Wild. 19 of the 24 hourly heat index records at DFW (since 1953) have been set or tied during this year's relentless heat wave. The only other remaining years are 1966 (2), 1980 (2) and 2020 (1). Surprised the all-time record (well, since 1953) is only 117F at DFW. Really puts these 120F+ readings further north in perspective.

Not as highly ranked at the threaded stations with long periods of record, but certainly not cooler than average. IPT: 49th (of 129) in the threaded record, and 28th (of 79) at the airport. MDT: 34th (of 135) in the threaded record. Overall not a hot summer, no doubt, but I think it will still probably rank within the upper 1/3 of all years since 1895 statewide. So definitely not a cool summer either.

10th warmest on record (out of 76 years) at Capital City Airport (CXY):