Hot and Cold Day
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It sounds like a trick question: Can a single day be the hottest and the coldest a place has ever seen on a given date? This isn't a riddle it's just a rare quirk of meteorology. I'm Dave Thurlow for the Weather Notebook.

Every so often a weather station manages to score a record high and a record low in the same day. How can this happen? One thing that helps it to happen is dry air. It takes a lot of energy to heat up or cool down water in the atmosphere, or water vapor. So, when the air is dry or lacks water vapor the temperature can easily soar or plumet.

That was the case in Souix City, IA on this very day in 1997. That morning it was cool and crisp with a record low of 33 degrees. Then a warm front swept through and the temperature soared to a record high of 91 that afternoon.

Down-slope winds can cause huge temperature rises. Such as in Bakersfield, CA in January 1930. That days' readings rose from 23 in the morning to 75 in just two hours. Generally coastal towns are too humid for the mercury to gyrate to such an extent. But, it didn't take much for Melbourne, FL to score its record high of 97 after recording a morning low of 68 on May 22, 1998.

The most unusual feat, though, is to go from a record high in the afternoon to a record low before midnight. This takes a mighty cold front. Like the one that hit Oklahoma City on November 11, 1911. It was a spring-like 83 degrees in the afternoon, then the wind called a Blue Norther arrived. By midnight, any pioneers caught in short-sleeves had to put on heavy coats. The temperature had gone from 83 to 17 in just a few hours.

Our show is a production of the Mount Washington Observatory.