The quality controlled Iowa COOP data for October 2016 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 55.2° or 4.4° above normal while precipitation totaled 2.10 inches or 0.51 inches less than normal.   This ranks as the 23rd warmest and 70th driest October among 144 years of records.   A warmer October was last recorded in 2007.

Temperatures. Warmer than normal weather was the rule for most of October as only six days (7th-8th, 11th-12th and 20th-21st) during the month averaged cooler than usual.   Temperatures averaged ten or more degrees above normal on the 4th, 11th, 15th-17th and 28th-29th while the most abnormally cool day was the 13th at nine degrees below normal.   Burlington reported the highest temperature of the month with a 91° reading on the 17th when daily record high temperatures were recorded at numerous locations across the state.   Meanwhile, Iowa’s first freeze of the season was recorded at Little Sioux on the morning of the 7th.   The first hard freeze of the fall occurred over much of the northwest two-thirds of Iowa on the morning of the 13th with the lowest temperature recorded at Battle Creek with 23°.   However, by month’s end 10% of the state, mostly in far eastern and southeastern Iowa, had yet to see a temperature of 32° or lower.   Not since 1998 (32%) has more of the state entered November without a freeze.

Heating Degree Day Totals. Home heating requirements, as estimated by heating degree day totals, averaged 31% less than normal and 17% less than last year.   Thus far this heating season (since July 1) heating requirements are running 21% less than one year ago at this time and 39% less than normal.

Precipitation. A drier than normal weather pattern prevailed across most of Iowa during October.   Greater than normal rain totals were mostly confined to about the northern two or three tiers of counties.   Northeastern Iowa, which had been plagued with numerous heavy rain events in recent months finally got a break from the wet weather from the last week in September until October 25-26 when widespread rains of two to nearly three inches occurred.   October rainfall was less than one-half of normal over much of central and south central Iowa with ISU Agronomy Farm in eastern Boone County reporting the least rain at 0.47 inches.   Keokuk, thanks largely to a very isolated downpour of 4.98 inches of rain on the morning of the 5th, recorded the most rain during the month with 6.93 inches (however, the official Keokuk measurement site at the Lock & Dam partially missed this early month downpour and had a monthly rain total of 4.92 inches).   River flows at month’s end continue at well above seasonal normals along most of Iowa’s major rivers with below normal flows confined to smaller watersheds in south central Iowa.   While October precipitation was not excessive, it was enough to push the 2016 annual totals to new records at Osage and New Hampton.   These two locations join Charles City, Decorah and Cresco which surpassed their previous annual records in September.

Station	2016 Total	Previous Annual Record	Period of Record
Charles City	54.82 inches	51.35 in 1999	133 years
Decorah	54.02 inches	48.74 in 2007	128 years
Cresco	53.51 inches	47.87 in 1951	110 years
New Hampton	53.14 inches	51.88 in 2007	110 years
Osage	48.97 inches	45.72 in 1999	112 years

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

                 _____2016_______________________________________
                 OCT  SEP  AUG  JUL  JUN  MAY  APR  MAR  FEB  JAN
Maximum High:    242  225   32   17  238   65   84  135  213   29
Minimum High:      8   15   53  224   17   81   72    5   59   98
Maximum Low:     184  338   83  131  196   21   63  268  159   89
Minimum Low:       6    4   14   82   42   72   53   10   19   63
Maximum Precip:  118  295  196  151   84   92   72  124  141  156

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

                      2016                                    
                 OCT   SEP   AUG   JUL   JUN   MAY   APR   MAR   FEB
High Temp Bias   0.1   0.1   0.1   0.1   0.2  -0.1   0.2   0.4   0.6
High Temp STD    2.2   2.0   1.8   1.9   2.1   2.0   2.5   2.6   2.4
Low  Temp Bias   0.2   0.1   0.1   0.2   0.2   0.2   0.2   0.3   0.2
Low  Temp STD    2.5   2.3   2.0   2.0   2.3   2.5   2.4   2.7   2.4
Precip    Bias   0.00 -0.01 -0.01 -0.02 -0.02  0.00  0.00  0.00  0.01
Precip    STD    0.12  0.27  0.30  0.29  0.25  0.17  0.11  0.09  0.07