COLUMBIA, Mo. (AP) -- The summer of 2009 is turning out to be one of the coolest on record in Missouri.

University of Missouri Extension Climatologist Pat Guinan says the season will rank among the 15 coolest on record, and possibly among the top 10.

Guinan attributes the temperatures to a northwest-flow upper-air pattern that dominated the Midwest for much of July and part of August. That flow led to frequent cool-air intrusions from Canada and extended periods of below-normal temperatures across Missouri.

Meanwhile, average rainfall statewide was higher than normal in June, July and August.

The summer conditions were mostly helpful for farmers. The Missouri Agricultural Statistics Service says most of the corn and soybean crops are in good to excellent condition.