July Weather Since 1990

One of the interesting parts of working in the golf world is dealing with weather.  It is important to understand weather variations over time when planning future projects and evaluating the success of past projects.  The last two summers have been hot and stormy, so I was curious: How "normal" is this weather?  When was the last summer with high heat and lots of rain?  The chart below summarizes July weather in Chicagoland since 1990.

(Click chart for full size view)

There are lots of ways to measure heat and precipitation, but I looked at the National Weather Service's departure from average figures for July. Out of curiousity, I also added in the number of days with rains over .5" -- big rains, in other words. 

The pattern confirms what I have heard from other Superintendents in the area.  Besides 2010, the last July we saw this extreme combination of high heat and heavy rain was . . . 1995.  Many people remember 1995 for its 100 degree days, but July also saw a lot of storms in this area.  We have had other unpleasant months over the years, but 1995, 2010, and 2011 really stick out for their combination of hot and wet -- one of the toughest situations for golf courses.

Notes on the chart:  Clicking on the chart will open a larger version.  Most of the data came from the National Weather Service.  I made a couple adjustments based on local measurements.  For instance, O'Hare measured over 11 inches July 2011 but we luckily missed a few of those inches.  It is important to note that this chart is only meant to summarize weather in July, not the entire summer.  There are many other factors in turfgrass health and golf playability, but July weather is very significant in our area.  I will take a look at August and its effects later this year.