Dear Tom,
On July 17, the dew point in the Rockford area reached the lower 80s. Was that a record?
Sandy Goetz, Rockford
Dear Sandy,
That day, dew points at many northern Illinois locations climbed to the lower 80s. Dew point values are not as well documented as other meteorological variables like temperature, so it is harder to determine records. This area’s highest dew points peak in the lower and middle 80s, so values that night were likely approaching record levels. Chicago’s record-high dew point is 83 (degrees), reached on July 30, 1999.
The world’s highest recorded dew point value is a suffocating 95 (degrees) observed at Dhahran, Saudi Arabia on July 8, 2003. When the dew point there was 95 (degrees), the temperature was 108 (degrees), resulting in an unimaginable heat index of 174 (degrees). Winds at Dhahran, which is located on the Persian Gulf, were onshore that day, bringing the extremely humid air inland.
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Tom Skilling is chief meteorologist at WGN-TV. His forecasts can be seen Monday through Friday on WGN-TV News at noon and 9 p.m.
Write to: ASK TOM WHY, 2501 Bradley Pl., Chicago, IL 60618 or asktomwhy@wgntv.com (Mail volume precludes personal response.)
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