Average Weather in May in Jefferson Iowa, United States
Daily high temperatures increase by 9°F, from 68°F to 78°F, rarely falling below 55°F or exceeding 87°F.
Daily low temperatures increase by 10°F, from 46°F to 57°F, rarely falling below 36°F or exceeding 66°F.
For reference, on July 18, the hottest day of the year, temperatures in Jefferson typically range from 65°F to 85°F, while on January 22, the coldest day of the year, they range from 14°F to 31°F.
Average High and Low Temperature in May
The figure below shows you a compact characterization of the hourly average temperatures for the quarter of the year centered on May. 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 May
The month of May in Jefferson experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 46% throughout the month.
The clearest day of the month is May 31, with clear, mostly clear, or partly cloudy conditions 56% of the time.
For reference, on December 29, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 55%, while on July 28, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 71%.
Cloud Cover Categories in May
0% clear 20% mostly clear 40% partly cloudy 60% mostly cloudy 80% overcast 100%
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Jefferson, the chance of a wet day over the course of May is increasing, starting the month at 35% and ending it at 40%.
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 11.
Probability of Precipitation in May
The average sliding 31-day rainfall during May in Jefferson is increasing, starting the month at 3.5 inches, when it rarely exceeds 5.8 inches or falls below 1.4 inches, and ending the month at 4.1 inches, when it rarely exceeds 7.2 inches or falls below 1.7 inches.
Average Monthly Rainfall in May
Over the course of May in Jefferson, the length of the day is increasing. From the start to the end of the month, the length of the day increases by 58 minutes, implying an average daily increase of 1 minute, 56 seconds, and weekly increase of 13 minutes, 31 seconds.
The shortest day of the month is May 1, with 14 hours, 3 minutes of daylight and the longest day is May 31, with 15 hours, 1 minute of daylight.
Hours of Daylight and Twilight in May
The latest sunrise of the month in Jefferson is 6:13 AM on May 1 and the earliest sunrise is 28 minutes earlier at 5:44 AM on May 31.
The earliest sunset is 8:16 PM on May 1 and the latest sunset is 29 minutes later at 8:45 PM on May 31.
Daylight saving time is observed in Jefferson during 2018, but it neither starts nor ends during May, so the entire month is in daylight saving time.
For reference, on June 21, the longest day of the year, the Sun rises at 5:42 AM and sets 15 hours, 15 minutes later, at 8:56 PM, while on December 21, the shortest day of the year, it rises at 7:42 AM and sets 9 hours, 7 minutes later, at 4:49 PM.
Sunrise & Sunset with Twilight in May
The chance that a given day will be muggy in Jefferson is increasing during May, rising from 1% to 10% over the course of the month.
For reference, on July 21, the muggiest day of the year, there are muggy conditions 55% of the time, while on November 8, the least muggy day of the year, there are muggy conditions 0% of the time.
Humidity Comfort Levels in May
dry 55°F comfortable 60°F humid 65°F muggy 70°F oppressive 75°F miserable
The average hourly wind speed in Jefferson is decreasing during May, decreasing from 12.5 miles per hour to 10.7 miles per hour over the course of the month.
For reference, on April 12, the windiest day of the year, the daily average wind speed is 13.2 miles per hour, while on August 3, the calmest day of the year, the daily average wind speed is 8.3 miles per hour.
Average Wind Speed in May
Wind Direction in May
The growing season in Jefferson typically lasts for 5.8 months (178 days), from around April 18 to around October 12, rarely starting before March 31 or after May 6, and rarely ending before September 25 or after October 30.
The month of May in Jefferson is more likely than not fully within the growing season, with the chance that a given day is in the growing season increasing from 82% to 100% over the course of the month.
Time Spent in Various Temperature Bands and the Growing Season in May
The average accumulated growing degree days in Jefferson are increasing during May, increasing by 368°F, from 217°F to 585°F, over the course of the month.
Growing Degree Days in May
The average daily incident shortwave solar energy in Jefferson is gradually increasing during May, rising by 0.6 kWh, from 5.9 kWh to 6.6 kWh, over the course of the month.
Average Daily Incident Shortwave Solar Energy in May
For the purposes of this report, the geographical coordinates of Jefferson are 42.015 deg latitude, -94.377 deg longitude, and 1,047 ft elevation.
The topography within 2 miles of Jefferson contains only modest variations in elevation, with a maximum elevation change of 112 feet and an average elevation above sea level of 1,042 feet. Within 10 miles also contains only modest variations in elevation (276 feet). Within 50 miles contains only modest variations in elevation (801 feet).
The area within 2 miles of Jefferson is covered by cropland (83%) and artificial surfaces (15%), within 10 miles by cropland (98%), and within 50 miles by cropland (94%).
This report illustrates the typical weather in Jefferson 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 4 weather stations near enough to contribute to our estimation of the temperature and dew point in Jefferson.
For each station, the records are corrected for the elevation difference between that station and Jefferson 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 Jefferson is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Jefferson and a given station.
The stations contributing to this reconstruction are: Perry Municipal Airport (40%, 28 kilometers, southeast); Arthur N Neu Airport (28%, 34 kilometers, west); Boone Municipal Airport (20%, 44 kilometers, east); and Fort Dodge Municipal Airport (12%, 62 kilometers, north).
Time zones for aiports and weather stations are provided by AskGeo.com .