Cool has been the rule around the Midwest since the end of July. Repeated shots of fresh Canadian air have kept temperatures well below the seasonal averages. Here's the temperature departures for the Midwest since July 22nd. Most of my local area is running 3-5 degrees below normal.
Here in Cedar Rapids, the past month (the period shown above) is the 8th coolest at the airport with a mean temperature of 69.4 degrees.
That's a radical change from earlier in the year when mild weather dominated from January through July. In fact, even if you take into account this recent month long cool spell temperatures for the year are still running warm enough to make 2017 the 5th warmest through August 21st.
Even more impressive are the temperature departures over the past 2 years. Here in Cedar Rapids (and most of my local area) the 2 year period is the warmest on record.
Below you can see what readings look like over the Midwest the past 2 years. Some parts of central Wisconsin have built departures of nearly 6 degrees. Not a single spot over the north central Midwest came close to experiencing normal temperatures. That is remarkable and why the past 2 years have been lean snow producers across the majority of the Midwest.
This cool pattern does look to be locked in for at least the remainder of August and much of September. Here's the 45 day temperature departure forecast from the CFSv2.
Stick a fork in it folks, summer 2017 is over. Roll weather...TS