Average Weather in January in Decatur Michigan, United States
In Decatur, the month of January is characterized by essentially constant daily high temperatures, with daily highs around 32°F throughout the month, rarely exceeding 47°F or dropping below 18°F. The lowest daily average high temperature is 31°F on January 22.
Daily low temperatures decrease by 2°F, from 22°F to 20°F, rarely falling below 4°F or exceeding 35°F. The lowest daily average low temperature is 19°F on January 29.
For reference, on July 19, the hottest day of the year, temperatures in Decatur typically range from 63°F to 82°F, while on January 29, the coldest day of the year, they range from 19°F to 31°F.
Average High and Low Temperature in January
The figure below shows you a compact characterization of the hourly average temperatures for the quarter of the year centered on January. 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 January
The month of January in Decatur experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 67% throughout the month.
The clearest day of the month is January 31, with clear, mostly clear, or partly cloudy conditions 34% of the time.
For reference, on December 29, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 68%, while on August 26, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 69%.
Cloud Cover Categories in January
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Decatur, the chance of a wet day over the course of January is rapidly decreasing, starting the month at 23% and ending it at 17%.
For reference, the year's highest daily chance of a wet day is 35% on July 30, and its lowest chance is 17% on February 3.
Over the course of January in Decatur, the chance of a day with only rain decreases from 11% to 7%, the chance of a day with mixed snow and rain remains an essentially constant 3% throughout, and the chance of a day with only snow remains an essentially constant 9% throughout.
Probability of Precipitation in January
The average sliding 31-day rainfall during January in Decatur is gradually decreasing, starting the month at 1.1 inches, when it rarely exceeds 2.7 inches or falls below 0.1 inches, and ending the month at 0.8 inches, when it rarely exceeds 2.0 inches.
The lowest average 31-day accumulation is 0.8 inches on January 29.
Average Monthly Rainfall in January
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 January in Decatur is essentially constant, remaining about 0.5 inches throughout, and rarely exceeding 1.1 inches or falling to 0.0 inches.
The highest average 31-day liquid-equivalent accumulation is 0.5 inches on January 5.
Average Monthly Liquid-Equivalent Snowfall in January
Over the course of January in Decatur, the length of the day is increasing. From the start to the end of the month, the length of the day increases by 49 minutes, implying an average daily increase of 1 minute, 38 seconds, and weekly increase of 11 minutes, 29 seconds.
The shortest day of the month is January 1, with 9 hours, 11 minutes of daylight and the longest day is January 31, with 10 hours, 0 minutes of daylight.
Hours of Daylight and Twilight in January
The latest sunrise of the month in Decatur is 8:12 AM on January 3 and the earliest sunrise is 15 minutes earlier at 7:57 AM on January 31.
The earliest sunset is 5:23 PM on January 1 and the latest sunset is 34 minutes later at 5:57 PM on January 31.
Daylight saving time is observed in Decatur during 2017, but it neither starts nor ends during January, so the entire month is in standard time.
For reference, on June 21, the longest day of the year, the Sun rises at 6:08 AM and sets 15 hours, 15 minutes later, at 9:23 PM, while on December 21, the shortest day of the year, it rises at 8:09 AM and sets 9 hours, 6 minutes later, at 5:15 PM.
Sunrise & Sunset with Twilight in January
The chance that a given day will be muggy in Decatur is essentially constant during January, remaining around 0% throughout.
For reference, on July 28, the muggiest day of the year, there are muggy conditions 40% 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 January
The average hourly wind speed in Decatur is essentially constant during January, remaining within 0.2 miles per hour of 13.5 miles per hour throughout.
For reference, on January 15, the windiest day of the year, the daily average wind speed is 13.7 miles per hour, while on August 4, the calmest day of the year, the daily average wind speed is 8.1 miles per hour.
The highest daily average wind speed during January is 13.7 miles per hour on January 16.
Average Wind Speed in January
Wind Direction in January
Decatur is located near a large body of water (e.g., ocean, sea, or large lake). This section reports on the wide-area average surface temperature of that water.
The average surface water temperature in Decatur is gradually decreasing during January, falling by 3°F, from 40°F to 37°F, over the course of the month.
Average Water Temperature in January
The growing season in Decatur typically lasts for 5.8 months (178 days), from around April 25 to around October 19, rarely starting before April 8 or after May 14, and rarely ending before September 30 or after November 9.
The month of January in Decatur is reliably fully outside of the growing season.
Time Spent in Various Temperature Bands and the Growing Season in January
The average accumulated growing degree days in Decatur is essentially constant during January, remaining around 1°F throughout.
Growing Degree Days in January
The average daily incident shortwave solar energy in Decatur is gradually increasing during January, rising by 0.6 kWh, from 1.5 kWh to 2.1 kWh, over the course of the month.
Average Daily Incident Shortwave Solar Energy in January
For the purposes of this report, the geographical coordinates of Decatur are 42.108 deg latitude, -85.974 deg longitude, and 758 ft elevation.
The topography within 2 miles of Decatur is essentially flat, with a maximum elevation change of 75 feet and an average elevation above sea level of 759 feet. Within 10 miles is essentially flat (387 feet). Within 50 miles contains only modest variations in elevation (574 feet).
The area within 2 miles of Decatur is covered by cropland (63%), trees (21%), and artificial surfaces (12%), within 10 miles by cropland (63%) and trees (32%), and within 50 miles by cropland (51%) and water (21%).
This report illustrates the typical weather in Decatur 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 5 weather stations near enough to contribute to our estimation of the temperature and dew point in Decatur.
For each station, the records are corrected for the elevation difference between that station and Decatur 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 Decatur is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Decatur and a given station.
The stations contributing to this reconstruction are: Hree Rivers Municipal Dr Haines Airport (23%, 36 kilometers, southeast); South Haven Area Regional Airport (23%, 36 kilometers, northwest); Ross Field-Twin Cities Airport (21%, 38 kilometers, west); Kalamazoo-Battle Creek International Airport (21%, 38 kilometers, east); and Michigan City Municipal Airport-Phillips Field (13%, 52 kilometers, southwest).
Time zones for aiports and weather stations are provided by AskGeo.com .