Does a Dry Spring Signal a Hot Summer to Come? (6/19/2011)

By: NWS Wichita

Does a Dry Spring Signal a Hot Summer to Come?


As everyone is fairly well aware of, spring 2011 (March-May) was quite dry across south-central Kansas. The three-month period measured a meager 4.88 inches at the Wichita Mid-Continent Airport, a whopping 4.96 inches below normal. Spring 2011 was in fact the 12th driest March-May period recorded in Wichita since 1889. The hypothesis going into this write-up was that an abnormally dry spring should produce an abnormally warm summer, since dry ground and an associated dry atmosphere tend to result in relatively warmer temperatures. But is this true from a historical perspective?

Averaging Wichita's driest March-May periods since 1889, with total precipitation deficits of at least 4 inches, yield average summer temperatures about 0.5 degrees above normal. In contrast, spring precipitation surpluses  of at least 4 inches yield an average summer temperature about 0.5 degrees below normal. In other words, dry springs typically yield summers that are only slightly warmer than normal, and wet springs typically yield summers that are only slightly cooler than normal.

Some dry springs have indeed produced relatively hot summers, such as 1936, 1933 and 1913. However, some dry springs also produced relatively cool summers, such as 1950 and 1967. Additionally, some of the hottest summers on record, such as 1934, 1980, 1954 and 2010 had preceding spring precipitation deficits of no more than 1 inch or so. 

It is interesting to note that 80% of the top-20 warmest summers since 1889 recorded spring precipitation deficits of some kind. In contrast, 65% of the top-20 coolest summers recorded spring precipitation surpluses of some kind.

In summary, abnormally dry springs in Wichita on average yield slightly warmer than normal summers, and abnormally wet springs on average yield slightly cooler than normal summers. However, there appears to be little correlation between a dry spring preceding a MUCH warmer than normal summer, nor a wet spring preceding a much cooler than normal summer.




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