The quality controlled Iowa COOP data for October 2015 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 53.0° or 2.2° above normal while precipitation totaled 1.78 inches or 0.83 inches less than normal.   This ranks as the 51st warmest and 53rd driest October among 143 years of records.

Temperatures. October began with slightly cooler than normal weather for the first four days of the month.   Estherville recorded Iowa’s first freeze of the season with a 32° reading on the morning of the 2nd.   However, a lower temperature was not recorded in the state until the 14th when several northeast Iowa locations reported 30° readings.   The first hard freeze arrived at scattered northwest Iowa locations on the morning of the 16th with a 27° reading at Spencer.   The next morning brought the lowest temperatures of the month with a 19° reading at Stanley and a hard freeze over much of the northeast one-half of the state.   All of Iowa, with the exception of Des Moines and Keokuk, had recorded at least a light freeze by the end of the month.   On the other extreme, temperatures reached into the eighties somewhere in the state on the 7th, 8th, 10th, 11th, 19th, 20th and 21st.   The warmest day in most areas came on the 11th when all reporting points except Dubuque Airport and Fort Madison reached 80° with Sioux City, Hawarden and Le Mars being the hot spots with daily record 91° readings.

Heating Degree Days. Home heating requirements, as estimated by heating degree day totals, averaged 12% less than last October and 17% less than normal.   Heating degree day totals thus far this season are running 20% less than at this point last year and 23% less than normal.

Precipitation. Exceptionally dry weather prevailed from September 30 until the morning of October 20 with only a handful of locations recording any measurable rain during the period.   Parts of northwest Iowa remained dry for a few more days until rain finally moved into that portion of the state on the 23rd.   The dry, and mostly warmer than normal weather, allowed for excellent conditions for harvest and ample in-field dry-down of corn and soybeans.   Rain was more frequent late in the month with about one-half of the October total arriving on the 27th-28th.   Rain totals for the month varied from 0.54 inches at Britt to 4.07 inches on the east side of Cedar Rapids and at Iowa City.   Despite the turn to greater rainfall late in the month only a few locations, mostly in east central and far northwest Iowa, recorded above normal precipitation for the month.   Iowa’s first snow of the season arrived in the northwest on the afternoon of the 28th but with little, if any, accumulation.

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

                 __________2015__________________________________
                 OCT  SEP  AUG  JUL  JUN  MAY  APR  MAR  FEB  JAN
Maximum High:     75  130   25   22   69   28   34  182   13  113
Minimum High:     21   13  269  261   88  316   28  102  364   65
Maximum Low:      79  336   38   54   32   82   34   29   25  135
Minimum Low:      20   25  156  139   26   87   76   98  345  111
Maximum Precip:  162  150  158  214  151  155  122   17  113   67

The following is a table summarizing how well the IEM daily data estimator is working in comparison to the quality controlled data.

                      2015
                 OCT   SEP   AUG   JUL   JUN   MAY   APR   MAR   FEB
High Temp Bias   0.2   0.0   0.1   0.0   0.0  -0.1   0.0   0.3   0.3
High Temp STD    1.8   1.7   1.8   1.7   1.7   2.5   2.2   2.6   2.8
Low  Temp Bias   0.1   0.0   0.2   0.2   0.2   0.1   0.3   0.4   0.3
Low  Temp STD    2.6   2.1   2.1   2.0   2.0   2.0   2.7   2.9   2.9
Precip    Bias  -0.01  0.01 -0.01  0.00  0.00 -0.01  0.00  0.01 -0.16
Precip    STD    0.08  0.26  0.27  0.29  0.33  0.20  0.13  0.13  0.05