Weather officials have certified a new dew-point record for Minnesota, meaning that for two hours on July 19, Moorhead residents sweated through their clothes faster than anyone in state history.
The record of 88 degrees, set from 7 to 9 p.m. July 19, broke the mark of 86 set at Pipestone and St. James on July 23, 2005.
Dew point is a measure of water vapor in the air. The higher the dew point, the more difficult it is for people's sweat to evaporate, which is how they would otherwise shed body heat. For the Twin Cities, where a record of 82 was set July 19, the long-term average summertime 6 p.m. dew point is about 58 degrees.
The Moorhead mark was questioned at first because the measuring device was in a soybean field, an extremely humid environment at the height of the growing season. The official National Weather Service reading at the time at the airport in neighboring Fargo was 83.
But assistant DNR state climatologist Pete Boulay said once the device was determined to be accurate, the record was easy to acknowledge. "The old record was in a similar situation, so it wasn't hard to make that leap," he said.
This year has already seen a record for hours with dew points of 75 degrees or higher in the Twin Cities. By Aug. 1, there had already been 98 such muggy hours, well beyond the old seasonal mark of 78 set in 2001.
Humidity has run high through July and the early days of August thanks to a convergence of moisture from the Pacific and the Gulf of Mexico and evaporation from crops. The humidity was not abnormal for summer, but its persistence was, Boulay said.
"It was the perfect storm for dew points," he said.
