The quality controlled Iowa COOP data for July 2014 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. Temperatures averaged 69.0° or 4.6° below normal while precipitation totaled 3.43 inches or 1.07 inches below normal.   This ranks as the fifth coolest and 67th driest July among 142 years of state records.   A cooler July was last recorded just five years ago.   While precipitation was below normal it was much greater than during the previous two Julys.

Temperatures. Below normal temperatures were the rule through most of the month with just six days (6th-7th, 12th, 21st-22nd and 26th) averaging warmer than usual.   Overnight lows in the forties were just as frequent as daytime highs in the nineties.    The month’s lowest temperatures were 44 degree minimums on the morning of the 16th at Little Sioux and Stanley while daytime highs reached only 62 degrees at Allerton and Rathbun Dam on the 2nd.   Summer heat did creep into southwestern Iowa on the 21st, 22nd and 25th with heat indices soaring to 117° at Audubon on the 21st and Shenandoah on the 25th (actual temperature of 93° with a dew point of 82° both times).   Sidney recorded the highest actual temperature during the month with a 98° reading on the 25th.   Several locations across northern and eastern Iowa have yet to reach 90 degrees this year.   At Burlington this is the first time that temperatures have not reached 90° by the end of July since records began in 1897.

Precipitation. The month began with widespread flooding in progress from frequent heavy rains in late June.   However, July brought much less rain with only three events bringing a statewide average rainfall of more than one-half inch (0.73 inches on the 5th-6th, 0.80 on the 11th-12th and 0.56 on the 24th-25th).   Monthly rain totals were much below normal over parts of southwest and far northern Iowa.   Atlantic reported the lowest total with 0.75 inches while Montezuma reported the most with 10.21 inches.   Mild temperatures and abundant subsoil moisture reserves allowed the statewide average corn and soybean ratings to improve slightly during the month despite the drier weather.   Pasture conditions declined very slightly during July but remained much better than usual for late July according to USDA NASS numbers.

Cooling Degree Day Totals. Home air conditioning requirements, as estimated by cooling degree day totals, averaged 42% less than last July and 46% less than normal.   Cooling degree day totals so far this year are running 16% less than last year and 19% less than normal.

Severe Weather. Unlike the previous month, July 2014 was a quiet month for severe weather.   There were only a few dates with relatively isolated severe thunderstorms.   Nevertheless, the evening of July 6 brought nine small tornadoes to central Iowa.

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

                 _____2014__________________________2013_________
                 JUL  JUN  MAY  APR  MAR  FEB  JAN  DEC  NOV  OCT
Maximum High:      4   27   79  118   24   26   79   21   18   31
Minimum High:    399   37  235  174  406  306  219  141  170   60
Maximum Low:       8  122  102   40    7    7   22   14   25   46
Minimum Low:     330   58  171  209  439  379  194  177  241   70
Maximum Precip:  134  342   92  187   29   91   36   41  123  138

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.

                 _____2014_______________________________2013__
                 JUL   JUN   MAY   APR   MAR   FEB   JAN   DEC
High Temp Bias   0.2   0.1   0.2   0.4   1.3   1.4   0.8   0.7
High Temp RMSE   0.8   0.7   0.8   0.8   1.8   1.7   1.3   1.0
Low  Temp Bias   0.2   0.1   0.1   0.2   2.1   2.7   1.4   1.3
Low  Temp RMSE   1.0   0.8   0.9   1.0   2.4   2.9   1.6   1.6
Precip    Bias   0.2   0.13  0.20  0.14  0.36  0.31  0.49  0.24
Precip    RMSE   0.92  1.39  0.64  0.63  0.46  0.56  0.59  0.31