The quality controlled Iowa COOP data for January 2017 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 23.9° or 4.5° above normal while precipitation totaled 1.61 inches or 0.69 inches above normal.   This ranks as the 28th warmest and 23rd wettest January among 145 years of records.   A warmer January was last recorded in 2012 and a wetter one in 1996.

Temperatures. Relatively mild air prevailed across Iowa for most of January.   There were only seven days (4th-8th and 12th-13th) averaging cooler than usual.   Lowest temperatures were -14° readings at Northwood, Postville and Cresco on the morning of the 6th and again at Cresco on the morning of the 8th.   Subzero temperatures were recorded only once during the second one-half of the month when Cresco registered -2° on the morning of the 30th.   Meanwhile daily maximum temperatures reached into the fifties four times (10th, 18th, 21st and 30th) with Shenandoah the warmest with a 58° reading on the afternoon of the 30th.

Heating Degree Day Totals. Home heating requirements, as estimated by heating degree day totals, averaged 10% less than last January and normal.   Thus far this heating season (since July 1) heating requirements are running 1% less than last season at this time and 15% less than normal.

Precipitation.Monthly precipitation totals were above normal at all but a handful of scattered locations during January.   January precipitation amounts varied from 0.62 inches at Rock Rapids to 2.89 inches at Waterloo (where this was the third wettest January among 133 years of records).   Much of this precipitation came in the form of rain.   Rain was widespread on the 2nd-3rd, 10th, 15th-16th, 19th and 20th-21st.   The most notable of these rain events was the mid-month storm which brought considerable freezing rain to all but the far southeast corner of Iowa.   A few southeast Iowa locations picked up more than one inch of rain during this storm while greatest ice accumulations of around one-quarter inch coated a wide band across southwest, central and northeast Iowa.   Unseasonably heavy rain of a half-inch or more also fell over parts of central and northeast Iowa on the 10th.   The only snow event of consequence was a large one on the 25th-26th.   Six inches or more of snow fell across all of northwest and north central Iowa with Mason City reporting the most snow with 15.0 inches.   This one storm accounted for nearly all of the January snow in Iowa with a handful of other events bringing light accumulations to fairly small areas scattered across the state.  Monthly snow totals varied from only a trace at Fairfield (their lowest January total since no snow fell in 1989) to 15.7 inches at Mason City.   A statewide average of 4.5 inches of snow fell during the month, 3.0 inches less than normal.   This ranks as the 31st lowest January snow total among 130 years of records with a lower January total recorded just last year (3.7 inches).

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

                 2017_______2016_________________________________
                 JAN  DEC  NOV  OCT  SEP  AUG  JUL  JUN  MAY  APR
Maximum High:     43   40  226  242  225   32   17  238   65   84
Minimum High:     36   44   21    8   15   53  224   17   81   72
Maximum Low:     367   70  125  184  338   83  131  196   21   63
Minimum Low:      23   99   15    6    4   14   82   42   72   53
Maximum Precip:  219  167   85  118  295  196  151   84   92   72

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

                 2017     2016                                
                 JAN   DEC   NOV   OCT   SEP   AUG   JUL   JUN   MAY
High Temp Bias   0.2   0.3   0.2   0.1   0.1   0.1   0.1   0.2  -0.1
High Temp STD    2.0   2.0   2.1   2.2   2.0   1.8   1.9   2.1   2.0
Low  Temp Bias   0.0   0.1   0.0   0.2   0.1   0.1   0.2   0.2   0.2
Low  Temp STD    2.3   2.3   2.8   2.5   2.3   2.0   2.0   2.3   2.5
Precip    Bias   0.01 -0.02  0.00  0.00 -0.01 -0.01 -0.02 -0.02  0.00
Precip    STD    0.07  0.07  0.09  0.12  0.27  0.30  0.29  0.25  0.17