Hottest Day In Years

Though we approached and even exceeded 100 around the 4th of July last year, today's heat will be the highest in years.  Lowell, MA is forecast to reach 103 while Boston is forecast to reach 101.  High pressure is responsible for this near record heat.  When high pressure is over an area the air sinks, or compresses the atmosphere to the surface.  The longer the high sits, the hotter the air becomes because it cannot move.  The air expands and spreads out which is why there is such widespread heat.  An excessive heat warning is in effect for this afternoon.

Tomorrow will also be hot, high of 98.  A boundary will pass through the area and when that moves through there is a chance that thunderstorms could fire.  Given the extreme heat in place it wouldn't take much of a trigger  later on Saturday.  Northern areas of New England are most at risk.  Temperatures will return to the upper 70's early next week.  I for one cannot wait.  I'd rather it be -10 than 100, I don't think I could live where its hot and humid all spring and summer.

All this heat wave talk made me curious as to where it compares to past heat waves in history.  Here is a breakdown by decade of when each of the 50 states all time high temperature occurred
Source- World Almanac and Book of Facts 2011, click to enlarge

Well obviously the 1930's stick out.  When it comes to global warming, no one ever said the earth wasn't warming in the 1980's and 1990's (who had credibility anyway).  What was debated was how unprecedented the warming was.  The 1930's were incredibly hot.  For example lets look at Des Moines, IA.  In July 1936 Des Moines went 17 straight days with temperatures over 100.  12 records from 1936 still stand.  In fact, the city has set only 1 record high in July since 1955 and that was July 23, 1991.  Kansas City still has 8 record highs from July 1954 alone and 15 records from the 1930's.  17 July records in Lincoln, NE are from the 1930's and 1 is from 2011.  10 days in July 1954 in Lincoln exceeded 100 degrees.  So far this summer there has been 3.  13 record highs from July 1936 in Springfield, IL are still standing.

For those who live in New England the worst stretch we saw was from July 1911.  Yeah, 100 years ago Boston spent 4 straight days over 100 degrees.  This was long before AC and many of the comforts we use to beat the heat today.  That is why over 350 people died during the stretch.  Boston's daily record highs for July 3, 4, and 6 still stand from that sweltering stretch.  Worcester has 5 records still standing from July 1911. In fact Worcester set more daily July record highs in 1892 (4) than the 1990's and 2000's combined (2- both 1991).   CO2 was a lot less back then...

All values are taken from official National Service weather reporting stations courtesy of the history data on (weather underground).  

Stay cool today.


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