Monthly Weather Report

IOWA MONTHLY WEATHER SUMMARY – DECEMBER 2020

General Summary

Temperatures averaged 27.2 degrees or 4.3 degrees above normal, tying 1975 as the 48th warmest December on record. Precipitation averaged 0.94 inch or 0.40 inches less than normal, ranking it as the 54th driest (ties 1967). A warmer December occurred just last year while a drier one was last recorded in 2013.

Temperatures

Warmer than average conditions persisted through December with positive departures ranging from four to eight degrees statewide; northern Iowa reported the warmest conditions. December’s statewide average maximum temperature was 36.8 degrees, 5.2 degrees above normal while the average minimum temperature was 17.6 degrees, 3.2 degrees above normal. Centerville (Appanoose County) and Lamoni (Page County) reported the month’s high temperature of 66 degrees on the 10th, on average 29 degrees above normal. Mason City Municipal Airport (Cerro Gordo County), Northwood (Worth County) and Pocahontas (Pocahontas County) reported the month’s low temperature of -7 degrees on the 25th, on average 15 degrees below normal. Red Oak (Montgomery County) also observed this low temperature on the 31st, 20 degrees below normal for that station.

Heating Degree Day Totals

Home heating requirements, as estimated by heating degree day totals, averaged

7% more than last December and 9% less than normal. Thus far this heating season, heating degree day totals are running 4% less than last year at this time and 5% less than normal.

Precipitation

Much of the northern half of Iowa experienced drier than normal conditions on the order of 0.50 inch to one inch; a few counties in northeast Iowa observed negative departures approaching 1.50 inches. Southern Iowa, in particular southeastern Iowa, reported above normal totals of similar magnitudes. Multiple winter systems moved through Iowa leaving behind measurable snow statewide. Over the month, above average snow totals accumulated from Omaha northeast though Dubuque; portions of central and eastern Iowa measured totals of four to six inches above average. Monthly precipitation totals ranged from 0.12 inch at Ionia 2 W (Chickasaw County) to 2.78 inches in Muscatine (Muscatine County). The statewide average snowfall was 8.4 inches, which is 0.1 inch above normal liquid-equivalent totals.

US Drought Monitor

Drought and abnormally dry conditions remained across Iowa with drought boundaries remaining status quo. As of the first week of January, 61% of Iowa was covered in D0-D3 conditions; northwest Iowa still remains the driest part of the state with 4% of D3 (Extreme Drought) still remaining.

Justin Glisan, Ph.D.
State Climatologist of Iowa
Iowa Dept. of Agriculture & Land Stewardship
Wallace State Office Bldg.
Des Moines, IA 50319
Telephone: (515) 281-8981
E-mail: Justin.Glisan@IowaAgriculture.gov

WEATHER BY DISTRICTS