The quality controlled Iowa COOP data for August 2013 has been uploaded to the IEM. These observations are kindly provided by Harry Hillaker, our state climatologist, who passes along these notes on the month:

General Summary. Iowa temperatures averaged 72.2° or 0.7° above normal while precipitation totaled 1.57 inches or 2.63 inches less than normal. This ranks as the 7th driest and 62nd warmest August among 141 years of records.

Temperatures. Unseasonably mild air prevailed across Iowa from late July through the middle of August with all but one day in 27 averaging cooler than normal from July 23rd through August 18th (August 6 was the exception). The mild weather helped crops endure a prolonged period of unusually dry weather. However, heat returned in a big way in late August causing crops to deteriorate rapidly. Temperatures were above normal for the last 13 days of the month with the last week of August being the hottest week since early July 2012. The month's lowest temperatures were recorded on the morning of the 14th with 42° readings at Belle Plaine and Elkader. Ottumwa tied or broke their daily record minimum temperature on the 14th, 16th and 17th. Iowa's first triple digit temperatures of the summer were recorded at Donnellson, Fort Madison and Keokuk on the 28th at 100°. However much higher readings were recorded on the 30th when Des Moines and Fort Madison both reached 104°. The highest heat index of the year was recorded at Iowa City on the 28th at 108° (temperature of 97 with a dew point of 74).

Cooling Degree Day Totals. Home air conditioning requirements, as estimated by cooling degree day totals, averaged 8% greater than last August and 9% greater than normal. Air conditioning requirements for the year are running 30% less than last year at this time but 1% more than normal.

Precipitation. The very dry weather pattern that began in most areas in July intensified during August. Several southeast Iowa locations recorded no measurable rain during August with record low August totals set at numerous locations over the southern one-half of the state. A partial list of August records is listed below:

City	Aug 2013 Total	Old Record	Period of Record
Mt. Pleasant	0.00	0.21 in 1909	136 years
Keokuk	0.00	0.15 in 1901	144 years
Burlington	Trace	0.36 in 1901	132 years
Fort Madison	Trace	0.05 in 1901	131 years
Jefferson	0.04	0.44 in 1984	110 years
Williamsburg	0.06	0.31 in 1953	98 years
Bloomfield	0.09	0.32 in 1881 & 1953	96 years
Centerville	0.10	0.21 in 1901	117 years
Iowa City	0.12	0.43 in 1966	156 years
Belle Plaine	0.15	0.26 in 2003	123 years
Washington	0.15	0.24 in 1901	136 years
Marshalltown	0.17	0.46 in 1984	133 years
Chariton	0.19	0.37 in 1910	120 years
Lamoni	0.36	0.37 in 1909	104 years

A few locations in far western Iowa recorded above normal rain amounts during August with Underwood the wet spot at 5.14 inches. At Burlington this was also the driest summer on record with a 3.86 inch total (old record 3.87 in 1913). On the other extreme Dorchester reported 19.58 inches of rain for the summer.

Summer Summary. Temperatures for June, July and August averaged 71.2° or 0.4 below normal while precipitation totaled 8.34 inches or 5.37 inches less than normal. This ranks as the 15th driest and 47th coolest summer among 141 years of records.

The following is the number of new daily records set at COOP sites based on data back to 1951.

                 ____________2013_________________________2012___
                 AUG  JUL  JUN  MAY  APR  MAR  FEB  JAN  DEC  NOV
Maximum High:    160   13   43  169   28    0    0  157   87  152
Minimum High:    102  204   97  311  358    9   10   20    2    0
Maximum Low:     183   58   50   61   28    0    1   79   33   61
Minimum Low:      96  217   53  116  319   35    0    0    0    0
Maximum Precip:   44   51  103  302  226   74   82   93   91   40

The following is some bulk statistics on how well IEM's daily COOP data estimator is performing on a monthly basis versus this QC'd dataset.

                 ______2013____________________________________
                 AUG   JUL   JUN   MAY   APR   MAR   FEB   JAN
High Temp Bias   0.2   0.4   0.4   0.1   1.3   0.8   1.0   1.0
High Temp RMSE   0.8   0.9   0.8   0.8   1.6   1.1   1.3   1.4 
Low  Temp Bias   1.2   0.8   1.2   1.2   2.5   2.2   2.5   1.8
Low  Temp RMSE   1.6   1.3   1.4   1.5   2.6   2.3   2.6   2.1
Precip    Bias   0.00 -0.08 -0.39 -0.87 -0.56 -0.14  0.01 -0.07
Precip    RMSE   0.50  0.53  0.94  1.28  0.91  0.42  0.35  0.24