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About April Warmth

Posted On: 2005-05-02 08:39 PM      Author: Daryl Herzmann      Views: 21144
Link: http://mesonet.agron.iastate.edu/COOP/ 
Driving to work this morning, I caught a note that perhaps April was
one of the warmest (top 10) on record.  (Note that I am barely awake
at this time, so I may have misheard.) Anyway, the IEM collects lots
of data, so lets investigate.  Of course, this information is not
official.  The NWS and/or State Climatologist may have something
official to say.  Hopefully my numbers jive with theirs.

According to some crude math done on the ASOS network and preliminary
COOP reports, the average temperature was around 53.3 degrees.  This
doesn't quite reach the top ten.

 Year  Average Temp
 1925  56.37
 1955  56.27
 1977  55.94
 1981  55.25
 1942  54.85
 1985  54.31
 1948  54.31
 1946  53.83
 1941  53.77
 1987  53.76

Lets break the monthly data up into 10 day periods.  The top 5 years
for each period are:

   (*) denotes year that was also in the top 10 for month
  DAYS 1-10      DAYS 11-20     DAYS 21-30
 1991  56.36    1977* 65.91    1942* 63.46
 1981  53.96    1985* 61.85    1962  61.52
 1925* 53.26    1931  61.14    1989  61.47
 1963  52.94    1938  59.72    1970  61.36
 1930  52.80    1941* 59.46    1990  61.21

 2005  54.4     2005  57.5     2005  46.4

It is interesting that, for the most part, years with the warmest 10
day periods did not appear in the top 10 for the entire month. Also,
the extremes of April 21-30 are not much larger than April 11-20.

Digging deeper, lets look at the warmest first 20 days of April

  DAYS 1-20    20-30
 1977* 55.75   56.31
 1955* 55.31   58.19
 1925* 55.21   58.70
 1976  54.42   50.49
 1931  54.19   44.34

 2005  55.9    46.4

So perhaps, the first 20 days of April were the warmest on record :) 
Again, not official!