The quality controlled Iowa COOP data for December 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. Iowa temperatures averaged 28.1° or 5.2°above normal while precipitation totaled 1.14 inches or 0.20 inches below normal. This ranks as the 35th warmest and 67th wettest December among 142 years of records.

Temperatures. The cold weather pattern that dominated the month of November persisted only into the first three days of December. Above normal temperatures prevailed on all but two days between the 4th and 28th. There were two prolonged periods averaging more than ten degrees warmer than normal from the 12th through the 15th and from the 21st through the 26th when overnight low temperatures were frequently higher than typical daytime high readings. The month's highest temperatures of 60° were recorded on the 14th at Shenandoah and Sidney. Subzero temperatures were confined to only December 1st, and again over the last four days of the month. Sanborn recorded the lowest temperature of the month with a -16° reading on the morning of the 30th while wind chills bottomed out at -33° the same morning at Storm Lake. Soils, which had frozen to a depth of three to eight inches during the unusually cold November, were completed thawed in many areas by Christmas. However, frost depths quickly returned to the 3 to 8 inch range in response to sharply colder weather at the end of December.

Heating Degree Day Totals. Home heating requirements averaged 23% less than last December and 13% less than normal for the month. Heating requirements thus far this winter season (since July 1) are running 6% less than last year at this time but are 1% more than normal.

Precipitation. December began very dry with no measurable precipitation anywhere in the state until the 7th. Most of the month's precipitation came in two events. The first storm system brought light to moderate rain statewide from the 14th to the 16th with the rain changing to very light snow in the far northwest late in the event. The second event also brought light to moderate rain statewide between the 22nd and 24th before changing over to one to four inches of snow across the northwest one-half of the state. One last event brought one to four inches of snow to the northwest one-third of Iowa on the night of the 26th. Monthly precipitation totals, coming mostly as rain, were above normal over most of northwestern Iowa but decreased to about one-half of normal over the far southeast. Precipitation totals varied from 0.47 at Allerton to 2.51 inches at Little Sioux. The statewide average snowfall for the month was only 1.6 inches or 6.7 inches below normal. This is the lowest December snow total since 2006 and 13th lowest among 128 years of records. Numerous locations in eastern Iowa had no measurable snow during the month such as Davenport, Dubuque and Iowa City. Saint Ansgar reported the most snow with 8.1 inches.

Annual Summary. Iowa's 2014 temperatures averaged 45.4° or 2.7° below normal while precipitation totaled 39.66 inches or 4.39 inches above normal. This ranks as the 6th coolest and 14th wettest year among 142 years of records. A cooler year was last recorded in 1917 and a wetter one in 2010. Annual temperature extremes varied from a low of -29° at Elkader on January 28 and February 11 and a high of 98° at Sidney on July 25. There were three months ranking among the top ten for low temperatures (February 7th coldest among Februarys, July 5th coolest and November 4th coldest; while only December averaged more than one degree above normal. Annual precipitation totals varied from 25.93 inches at Estherville to 56.35 inches at Greenfield. Record high annual precipitation totals were recorded at Greenfield, Castana, Denison and Mapleton.

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

                 __________2014__________________________________
                 DEC  NOV  OCT  SEP  AUG  JUL  JUN  MAY  APR  MAR
Maximum High:     84   24   97   25   25    4   27   79  118   24
Minimum High:     60  634   89  267  161  399   37  235  174  406
Maximum Low:     451    5   56   86  113    8  122  102   40    7
Minimum Low:      28  550   22  180   33  330   58  171  209  439
Maximum Precip:  121   67  149  176  182  134  342   92  187   29

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_______________________________
                 DEC   NOV   OCT   SEP   AUG   JUL   JUN   MAY
High Temp Bias  -0.5   0.4   0.4   0.2   0.0   0.2   0.1   0.2
High Temp RMSE   0.9   0.8   0.8   0.8   0.7   0.8   0.7   0.8
Low  Temp Bias  -0.9   0.1   0.2   0.2   0.1   0.2   0.1   0.1
Low  Temp RMSE   1.0   0.9   0.9   0.9   0.8   1.0   0.8   0.9
Precip    Bias   0.03  0.15  0.26  0.33  0.39  0.2   0.13  0.20
Precip    RMSE   0.20  0.25  0.51  0.75  1.11  0.92  1.39  0.64