Have The Temperatures Since May 15 Really Been That Cool?

 

My cucumber plants are loving the frequent showers. Took a risk planting on May 7th this year. Thankfully, we survived some of the colder mid May nights.

Yet the bigger question remains. Have temperatures since mid May really been that "cool"?

Before we take a deep dive into years past, put the earlier spring weather especially April and early May aside.  April and most of May for that matter was governed by the stratospheric warming in the higher latitudes in mid March. A winter pattern that developed late in the season. We felt the effects in spring with above normal rainfall and cooler than normal temperatures. That will alter your perception significantly.      I wrote about this last month. LINK HERE. This major driver was fading by mid May. Since we are into the last half of June, looking back to mid May is more appropriate. All temperature maps and charts are from May 15 to June 15-17 and give the temperatures vs the 30 year averages.

First, the average temperatures for Cleveland vs normal since May 15. Obviously a big drop off this year yet pretty much in line with 2023!  Most of the last 20 years have featured warmer than normal late springs. 2025 overall has been more in line with the 1980s and early 1990s.

How about just the average HIGH TEMPERATURES? 

Obviously a big drop off this year. Again the last 20 years featured warmer than normal high temperatures in late spring.

Now the average LOW TEMPERATURES. 

2023 was cooler. The early 2000s and 2010s warmth definitively featured here similar to the above charts.

How about the number of days at/above 80 degrees?

This is where this year stands out. We've only had FIVE days at/above 80 since May 15th. Only three other years had less:  2003, 1997 and 1948.  

Another way of showing this is to look at the number of days UNDER 70:

2025 is more in line with the late springs of the 1990s and early 2000s.

The extremes are what we remember, not so much the averages!

Since we are comparing year to year, how about rainfall between May 15 and June 17th?

Plenty of years similar in recent memory.  Remember not to think about April and early May's rainfall. That was due to a completely different set of weather drivers. LINK HERE. 

A few things to note, we are only looking at ONE location (Cleveland) over a select 30 day period. This late spring has been very similar across the southern Great Lakes, Ohio Valley and the entire mid-west!

Average Temperatures VS Normal - May 15 to June 15

Rainfall rates are starting to slow especially across the Ohio Valley over the last 30 days.

Rainfall Rate VS Normal Since May 15th

The take home message is that this late spring has been "cooler" than in recent years here in northern Ohio AND much of the central US. While the rainfall is closer to normal since mid May, our average temperatures whether you look at the highs or the lows are more in line with what we would have experienced in the 1990s/early 200s during the same period. Even the number of days in the 50s and 60s since May 15 is similar to the 1990s. The fact that we've only had 5 days above 80 degrees since May 15 makes it seem that much cooler.  If it weren't for the Stratospheric Warming in mid March, more than likely our spring weather (April and May) would have been much different!

The pattern as outlined earlier this month is starting to switch to summer. Get ready!