A Very Mild May In The US

The frequency of hot May days has declined sharply in the US over the past century, with this year being just about average.

However, the average temperature this month has been in the top five.

Afternoon temperatures have been much cooler than 1934.


Maximum temperatures are decreasing, minimum temperatures are increasing – so the daily range in temperatures has plummeted.

One of the main reasons for the warmer nights and cooler days is the latent heat of water.  The US is getting wetter and having fewer droughts, so we get more evaporation during the day and more condensation at night. This moderates both daytime and nighttime temperatures.

Climate at a Glance | National Centers for Environmental Information (NCEI)

The hottest May was also the driest May in the US. During May, 1934 most of the US was in severe or extreme drought.  That was also the May with the largest diurnal temperature range.

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On Memorial Day weekend 1934, North Dakota reached 111 degrees, and almost the entire Great Plains was over 100 degrees.

The propaganda about hottest May ever is about to start, and I wanted everyone to be prepared with facts.

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9 Responses to A Very Mild May In The US

  1. NavarreAggie says:

    “That was also the May with the largest diurnal temperature range.”

    In other words, as the landscape aridifies during drought (or drought-like) conditions, the diurnal temperature differentials approach those of deserts. People are so dense. It stupefies me that people don’t understand the effects of humidity on temperature variations.

    I really do appreciate the common-sense approach to this discussion, Tony.

  2. Mohatdebos says:

    Joe Bastardi has reported that this may be the warmest May for the continental U.S. ever. His maps show it being warmer than normal in Michigan and Ohio. However, I live in Michigan and, until this week, it has been much colder. I respect Joe, but I would like to see your chart of upper Midwest temperatures as compared to average.

    • AZ1971 says:

      The “warmest May evah” schtick has to do with the weather pattern, not climate. It’s been normal here in Arizona, which (don’t get me wrong) is awesome. We’ve only had a few days in the triple digits, and with the massive UHI effect around the official reporting station at Sky Harbor Airport, most of those 100+ readings were a solo location while surrounding reporting stations were a few degrees shy of that.

      And honestly, anyone who says they know what the global temperature has been in most locations outside the UK and USA are kidding themselves.

      • RAH says:

        Joe is just talking about the US. Said it will be either the 2nd (after 1981) or 1st hottest May for the US on record.

    • Squidly says:

      It is nowhere near the hottest May ever, here in Tennessee.

      Additionally, I was watching live Motocross from California (just south of L.A.) and they complained that it was “cold”. They also remarked several times that prior Memorial Day races at this venue have typically been very hot, with spectators begging to be sprayed with water when the water truck happens by.

      I was also watching the Fort Worth Invitational PGA Golf Tournament from Fort Worth, Texas. They periodically remarked how prior Fort Worth Invitational tournaments have been much hotter and how nice and mild the weather was today.

      Anecdotally, you are going to find it very difficult to convince me that this is the “hottest May evah” … not a chance!

      And I just took a spin around the weather forecasts for some of my saved favorites (including Richland, WA and Fargo, ND) .. I see some rather warm temperatures followed by rather cool temperatures … nothing unusual at all.

  3. Andy DC says:

    Temperatures have been averaging 8-10 degrees above normal over much of the Midwest. It does not help our cause to deny the actual facts. But it is also a fact that April was the coldest on record for many Midwest stations as well. It is simply a variable weather pattern that has nothing to do with CO2 or global warming. According to the GFS model, the pattern could flip again and get June off to a very cool start over much of the US.

  4. ClimateYogi says:

    It certainly has not been the “warmist May evah” here on the Hāmākua Coast of the Big Island of Hawai`i . I don’t think we have any USHCN stations here . We do have a unfortunate factor to adjust for though . The “Hot Lava Running Through Your Yard Index”. That is a very local siting issue at the moment . Upcountry it is been a cool and moist year so far . Have the wood stove burning tonight ……..

  5. Psalmon says:

    Found this fascinating…told Spring coming early…in some places yes, others later.

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