Tuesday, August 13, 2013

Will Below Normal Temps Continue into September?


My projection for August given the "cooler than normal" July and comparing it to the July summers similar to 2013 yielded this:

So far through the 10th, this is what has ACTUALLY HAPPENED...not a bad match. Red dot is over Ohio.

The years that featured summers with "cooler" high temperatures than this summer through August 10th are:  2009, 2004, 2003, 2000, 1997, 1996, 1992, 1990, 1985, 1972, 1969, 1965, 1960, 1958, 1940, 1938, 1937, 1936, 1935.

I charted the summer average daytime high temperatures since 1933 (81 summers). The summers that were "cooler" than this summer are circled in blue  (20 of the last 31 years). The red line is the average over the 81 summers.This summer is indicated with the red arrow on the right.

How about September?

The most recent "cooler" summers since 2000 don't necessarily mean that September will always be cool.  In fact, September of 2009 was near normal while 2004 (a summer markedly cooler than 2013) was above normal.

Since daytime highs above 80 are considered "above normal" in September (daytime highs start to drop significantly), I plotted the number of days at or above 80 in each September from each year (listed earlier). What does this show?

 Overall, we average about a weeks worth of days above 80 in Septembers that follow cool summers similar or cooler than 2013

Here is what the temperatures looked like for each day in September of 2009. I circled the 80 degree days AND the 60 degree days. Notice how they become more numerous later in the month.

I believe that this September will look something like 2009. A handful of 80 degree days, a handful of 60 degree days toward the end with the rest feeling similar to this week!