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C-U Monthly Weather Review: August 2019

As we came out of a July that was nothing like we’d expected (hot and dry vs cool and stormy), I cautioned that we were in a period of low predictability heading into the month of August, but that it did seem we were headed for a pretty average August overall.

This turned out to be an excellent forecast as it pertains to temperatures, as we finished August with an average temperature of 73.4 degrees, only 0.2 degrees from the monthly average in Champaign-Urbana.

I came up a little dry when it comes to precipitation. After a very dry July, we began to see the early stages of drought conditions emerging across Central Illinois, including right here in Champaign County. Our lawns were turning crunchy and brown, and watering the garden became a daily chore.

We did see a slight uptick in precipitation across the area which has tempered some of the dryness concerns, but we still came up 1.74″ short of the monthly average with 2.19″ being measured at the Illinois State Water Survey, where Champaign-Urbana’s official records are kept.

It’s worth mentioning that some folks actually saw quite a bit more rainfall in August in neighboring parts of Champaign County. The nature of summer precipitation is that it’s quite unevenly distributed. We get most of our rainfall in the late summer from thunderstorms, and thunderstorms are highly local events. While your town may see a downpour, your neighbors five miles up the road may have stayed dry. At any rate, it was another dry month in Champaign-Urbana compared to the average.

How’d we do it all? Well, rather than seeing a month that offered stretches of both extreme heat and very cool weather, August truly was very average with respect to temperatures in the Twin Cities. Of the 31 days in August, only one day was more than five degrees off from the daily average. This came on the warmest day of the month, when we saw a high temperature of 91 degrees on August 19th. This was one of only two 90 degree days in Champaign-Urbana last month!

The thing that was most noticeable about this August in C-U though, was the continuous reinforcing shots of cooler, drier air that we saw. I only recall a handful of days where muggy conditions made things uncomfortable. Otherwise, it was a month of me throwing our windows open every night to let in that cool, crisp, autumn-like air! So while temperatures were very close to average all month long, lower humidity made it feel a bit cooler than usual at times.

August came in a bit drier, but we did see rain and thunderstorms on 10 of the 31 days of the month. The weather caused quite the local commotion on August 20th when a line of severe storms moved into Champaign County during the late morning. An ominous shelf cloud preceded the storms with all sorts of low-hanging, scary looking clouds on the leading edge. This prompted a funnel cloud to be reported by local law enforcement and triggered the outdoor warning sirens to be sounded across town.

Although we did see rain opportunities every four or five days through the month, it wasn’t until the 27th that we saw our first significant rainfall. After small drinks of only a tenth of an inch or so, we finally received almost an entire inch of rain in one day when several thunderless tropical downpours moved through the area.

Looking ahead to September, things look a bit more active across the Midwest. We’re off to a cooler start, and it does appear September will carry a cooler bias overall in Central Illinois. That said, it does appear we’re headed for at least a short run of warmer conditions that could see us firting with more summerlike temperatures during the middle part of the month. We may well see another 90 degree day or two between September 10-20. Along with that, a more active pattern may emerge sending more organized storm systems into the area perhaps accompanied by several more significant rainfall events. I wouldn’t even rule out another round or two of severe weather mid-month.

Overall, my bet is that on October 1st we’re looking back at a September that finishes a bit cooler than average, with rainfall very close to average. For reference, the average temperature for the month of September in Champaign-Urbana is 66.2 degrees, and the average September precipitation is 3.13″.

Photos by Andrew Pritchard

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