Past IEM Features tagged: heat
Summertime heat has returned in a big way to Iowa with today expected to be even warmer than Sunday with highs well into the 90s and oppressive humidity levels. The NWS has issued a heat advisory for much of the state with some portions now in an Excessive Heat Warning! The featured chart looks at the period between the first and last Heat Advisory issued by NWS Des Moines and the number of events per year. July and August are the months that we see the combination of high temperatures and high humidities which are needed to drive the heat index well above 100 degrees.
Hot temperatures and tropical air are expected to conspire today to push heat indices well above 100 degrees. The featured chart displays the maximum heat index for the past 40 years at the Des Moines Airport sensor. Since 1989, exceeding 100 degrees has not been all that common and the highest recorded value was 110, which happened last year. All of this heat and humidity will help to fire strong thunderstorms this evening with the Storm Prediction Center issuing a moderate risk of severe weather today.