Average Weather in December in Earlham Iowa, United States
Daily high temperatures decrease by 9°F, from 41°F to 32°F, rarely falling below 15°F or exceeding 56°F.
Daily low temperatures decrease by 9°F, from 26°F to 17°F, rarely falling below -1°F or exceeding 38°F.
For reference, on July 20, the hottest day of the year, temperatures in Earlham typically range from 67°F to 85°F, while on January 21, the coldest day of the year, they range from 16°F to 32°F.
Average High and Low Temperature in December
The figure below shows you a compact characterization of the hourly average temperatures for the quarter of the year centered on December. The horizontal axis is the day, the vertical axis is the hour of the day, and the color is the average temperature for that hour and day.
Average Hourly Temperature in December
The month of December in Earlham experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 52% throughout the month. The highest chance of overcast or mostly cloudy conditions is 53% on December 29.
The clearest day of the month is December 1, with clear, mostly clear, or partly cloudy conditions 50% of the time.
For reference, on February 13, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 54%, while on August 26, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 71%.
Cloud Cover Categories in December
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Earlham, the chance of a wet day over the course of December is rapidly decreasing, starting the month at 16% and ending it at 9%.
For reference, the year's highest daily chance of a wet day is 43% on June 7, and its lowest chance is 8% on January 9.
Over the course of December in Earlham, the chance of a day with only rain decreases from 9% to 3%, the chance of a day with mixed snow and rain remains an essentially constant 2% throughout, and the chance of a day with only snow remains an essentially constant 4% throughout.
Probability of Precipitation in December
The average sliding 31-day rainfall during December in Earlham is decreasing, starting the month at 0.9 inches, when it rarely exceeds 1.9 inches or falls below 0.1 inches, and ending the month at 0.4 inches, when it rarely exceeds 1.1 inches.
Average Monthly Rainfall in December
We report snowfall in liquid-equivalent terms. The actual depth of new snowfall is typically between 5 and 10 times the liquid-equivalent amount, assuming the ground is frozen. As with rainfall, we consider the liquid-equivalent snowfall accumulated over a sliding 31-day period centered around each day.
The average sliding 31-day liquid-equivalent snowfall during December in Earlham is essentially constant, remaining about 0.3 inches throughout, and rarely exceeding 0.9 inches or falling below -0.0 inches.
The highest average 31-day liquid-equivalent accumulation is 0.4 inches on December 17.
Average Monthly Liquid-Equivalent Snowfall in December
Over the course of December in Earlham, the length of the day is essentially constant. The shortest day of the month is December 21, with 9 hours, 10 minutes of daylight and the longest day is December 1, with 9 hours, 24 minutes of daylight.
Hours of Daylight and Twilight in December
The earliest sunrise of the month in Earlham is 7:23 AM on December 1 and the latest sunrise is 19 minutes later at 7:42 AM on December 31.
The earliest sunset is 4:46 PM on December 7 and the latest sunset is 10 minutes later at 4:56 PM on December 31.
Daylight saving time is observed in Earlham during 2018, but it neither starts nor ends during December, so the entire month is in standard time.
For reference, on June 21, the longest day of the year, the Sun rises at 5:42 AM and sets 15 hours, 11 minutes later, at 8:53 PM, while on December 21, the shortest day of the year, it rises at 7:39 AM and sets 9 hours, 10 minutes later, at 4:49 PM.
Sunrise & Sunset with Twilight and Daylight Saving Time in December
The chance that a given day will be muggy in Earlham is essentially constant during December, remaining around 0% throughout.
For reference, on July 22, the muggiest day of the year, there are muggy conditions 56% of the time, while on January 1, the least muggy day of the year, there are muggy conditions 0% of the time.
Humidity Comfort Levels in December
The average hourly wind speed in Earlham is essentially constant during December, remaining within 0.3 miles per hour of 11.7 miles per hour throughout.
For reference, on April 1, the windiest day of the year, the daily average wind speed is 12.9 miles per hour, while on August 3, the calmest day of the year, the daily average wind speed is 8.2 miles per hour.
Average Wind Speed in December
Wind Direction in December
The growing season in Earlham typically lasts for 5.9 months (179 days), from around April 17 to around October 13, rarely starting before March 30 or after May 5, and rarely ending before September 24 or after November 1.
The month of December in Earlham is reliably fully outside of the growing season.
Time Spent in Various Temperature Bands and the Growing Season in December
The average accumulated growing degree days in Earlham are essentially constant during December, remaining within 3°F of 3,388°F throughout.
Growing Degree Days in December
The average daily incident shortwave solar energy in Earlham is essentially constant during December, remaining within 0.1 kWh of 1.9 kWh throughout.
The lowest average daily incident shortwave solar energy during December is 1.8 kWh on December 21.
Average Daily Incident Shortwave Solar Energy in December
For the purposes of this report, the geographical coordinates of Earlham are 41.492 deg latitude, -94.124 deg longitude, and 1,076 ft elevation.
The topography within 2 miles of Earlham contains only modest variations in elevation, with a maximum elevation change of 171 feet and an average elevation above sea level of 1,076 feet. Within 10 miles also contains only modest variations in elevation (384 feet). Within 50 miles contains only modest variations in elevation (830 feet).
The area within 2 miles of Earlham is covered by cropland (99%), within 10 miles by cropland (92%), and within 50 miles by cropland (89%).
This report illustrates the typical weather in Earlham year round, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016.
Temperature and Dew Point
There are 6 weather stations near enough to contribute to our estimation of the temperature and dew point in Earlham.
For each station, the records are corrected for the elevation difference between that station and Earlham according to the International Standard Atmosphere , and by the relative change present in the MERRA-2 satellite-era reanalysis between the two locations.
The estimated value at Earlham is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Earlham and a given station.
The stations contributing to this reconstruction are: Perry Municipal Airport (27%, 38 kilometers, north); Des Moines International Airport (25%, 40 kilometers, east); Creston Municipal Airport (14%, 58 kilometers, south); Osceola Municipal Airport (13%, 61 kilometers, southeast); Audubon County Airport (11%, 70 kilometers, west); and Atlantic Municipal Airport (9%, 78 kilometers, west).
Time zones for aiports and weather stations are provided by AskGeo.com .