Summer 2025 was an overall warm summer that had bookends at the beginning and end of cool weather. As headlined was it the heat or humidity that really got to people who prefer moderately cooler summers. The summer heat index was definitely adjusted higher into locations that were wetter and more humid in pockets over extreme Southeast Michigan from metro Detroit and north-northeast suburbs southwest into the Ann Arbor region south to the Ohio border) where many areas saw rainfall above normal. The rest of Southeast Michigan varied with pockets of above average rainfall to below normal. More general below normal rainfall was concentrated in the Saginaw Valley into mid Michigan.
The heat, humidity and rainfall made for a good growing season over the majority of the region - save for the Saginaw Valley into mid Michigan where again, rainfall was lighter.
Stormy weather wasn't an over of abundance this past summer though there are a few events worth noting. The first was already mentioned in a previous blog write-up that occurred June 18th; while a second occurred on July 28th when severe weather produced pockets of strong winds, scattered torrential rains and flooding. One of the worst noted areas was reported at Detroit Metro Arpt where 2.68" of rain in 2 1/2 hours creating flooding around the airport. That 2.68" of rain easily created a record rainfall for July 28th
Bookend cool spells gave relief to an other wise warm-hot summer. Although, the number of 90 degrees days during the summer was slightly above average at 14 with 12 average. We nearly added another in September at Detroit Metro Arpt with an 88 on 18th. The most notable cool spell in late August (as seen below), brought the temperatures down closer to the record low area for late August. After the hot and humid periods of the summer; it actually was a welcome relief for the close of the climatological 2025 summer.
August 2025
Finally; Even with the predominance of heat and humidity the average temperatures of 73.1 was only a degree above the normal /+1.0/ (the recent 30 year summer normal of 72.1 degrees). The 73.1 degree average placed the summer temperature in at the 21st warmer summer; just missing the top 20 warmest summer.
My Outlook for the summer was very suitable in both the temperature range and rainfall with variances of above or below also predicted rainfall.
SUMMER 2025 OUTLOOK
TEMPERATURES:
All researched data including current trends indicate normal summer temperatures while the analogues alone (in entirety) lean toward a slightly cooler summer (or 0.0 > -1.0 below) normal. The main issue with the analogues are the notable cooler summers in the first half of the sample from the late 1800s into the mid 20th century /1894 - 1950/. Temperatures averaged cooler back at that time when compared to today's updated warmer normals due to climate change and urban sprawl/heat island.
Considering all mentioned:
I look for normal or average summer temperatures /June - Aug/ with temperatures in the final analysis averaging -1.2 to +1.2 degrees of current normals.
RAINFALL:
All researched data suggests normal rainfall but also either below/above normal rainfall for summer must be considered and recommended. While there were some moderately wet summers, they were still at a minimum but then again; occurred in the analogue later years. This proves even more problematic since the wet area summers were more split with drier areas north and wetter areas south.
Making weather fun while we ALL
learn
Bill Deedler
- SEMI_WeatherHistorian
