Average Weather in May in Greenfield Iowa, United States
Daily high temperatures increase by 9°F, from 68°F to 76°F, rarely falling below 55°F or exceeding 85°F.
Daily low temperatures increase by 10°F, from 47°F to 57°F, rarely falling below 36°F or exceeding 66°F.
For reference, on July 20, the hottest day of the year, temperatures in Greenfield typically range from 66°F to 85°F, while on January 20, the coldest day of the year, they range from 16°F to 32°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
Çalxanqala, Azerbaijan (6,318 miles away); Yangquan, China (6,696 miles); and Koksan, North Korea (6,335 miles) are the far-away foreign places with temperatures most similar to Greenfield (view comparison).
The month of May in Greenfield experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 45% throughout the month.
The clearest day of the month is May 31, with clear, mostly clear, or partly cloudy conditions 57% of the time.
For reference, on February 12, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 53%, while on August 26, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 72%.
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 Greenfield, the chance of a wet day over the course of May is very rapidly increasing, starting the month at 33% and ending it at 42%.
For reference, the year's highest daily chance of a wet day is 44% on June 7, and its lowest chance is 8% on January 12.
Probability of Precipitation in May
The average sliding 31-day rainfall during May in Greenfield is increasing, starting the month at 3.6 inches, when it rarely exceeds 6.1 inches or falls below 1.3 inches, and ending the month at 4.3 inches, when it rarely exceeds 7.5 inches or falls below 1.7 inches.
Average Monthly Rainfall in May
Over the course of May in Greenfield, the length of the day is increasing. From the start to the end of the month, the length of the day increases by 56 minutes, implying an average daily increase of 1 minute, 53 seconds, and weekly increase of 13 minutes, 9 seconds.
The shortest day of the month is May 1, with 14 hours, 0 minutes of daylight and the longest day is May 31, with 14 hours, 56 minutes of daylight.
Hours of Daylight and Twilight in May
The latest sunrise of the month in Greenfield is 6:15 AM on May 1 and the earliest sunrise is 28 minutes earlier at 5:47 AM on May 31.
The earliest sunset is 8:15 PM on May 1 and the latest sunset is 29 minutes later at 8:44 PM on May 31.
Daylight saving time is observed in Greenfield 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 5:44 AM and sets 15 hours, 10 minutes later, at 8:54 PM, while on December 21, the shortest day of the year, it rises at 7:40 AM and sets 9 hours, 11 minutes later, at 4:51 PM.
Sunrise & Sunset with Twilight in May
The chance that a given day will be muggy in Greenfield is rapidly increasing during May, rising from 1% to 13% over the course of the month.
For reference, on July 22, the muggiest day of the year, there are muggy conditions 57% 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 May
dry 55°F comfortable 60°F humid 65°F muggy 70°F oppressive 75°F miserable
The average hourly wind speed in Greenfield is decreasing during May, decreasing from 12.1 miles per hour to 10.4 miles per hour over the course of the month.
For reference, on April 1, the windiest day of the year, the daily average wind speed is 13.0 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 May
Wind Direction in May
The growing season in Greenfield typically lasts for 5.8 months (176 days), from around April 18 to around October 11, rarely starting before April 1 or after May 5, and rarely ending before September 22 or after October 31.
The month of May in Greenfield is more likely than not fully within the growing season, with the chance that a given day is in the growing season increasing from 83% 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 Greenfield are increasing during May, increasing by 356°F, from 225°F to 580°F, over the course of the month.
Growing Degree Days in May
The average daily incident shortwave solar energy in Greenfield is gradually increasing during May, rising by 0.6 kWh, from 6.0 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 Greenfield are 41.305 deg latitude, -94.461 deg longitude, and 1,319 ft elevation.
The topography within 2 miles of Greenfield contains only modest variations in elevation, with a maximum elevation change of 171 feet and an average elevation above sea level of 1,323 feet. Within 10 miles also contains only modest variations in elevation (364 feet). Within 50 miles contains only modest variations in elevation (784 feet).
The area within 2 miles of Greenfield is covered by cropland (91%), within 10 miles by cropland (95%), and within 50 miles by cropland (92%).
This report illustrates the typical weather in Greenfield 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 Greenfield.
For each station, the records are corrected for the elevation difference between that station and Greenfield 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 Greenfield is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Greenfield and a given station.
The stations contributing to this reconstruction are: Creston Municipal Airport (37%, 34 kilometers, south); Atlantic Municipal Airport (21%, 50 kilometers, west); Audubon County Airport (17%, 58 kilometers, northwest); Perry Municipal Airport (14%, 63 kilometers, northeast); and Des Moines International Airport (12%, 72 kilometers, east).
All other weather data, including cloud cover, precipitation, wind speed and direction, and solar flux, come from NASA's MERRA-2 Modern-Era Retrospective Analysis . This reanalysis combines a variety of wide-area measurements in a state-of-the-art global meteorological model to reconstruct the hourly history of weather throughout the world on a 50-kilometer grid.
Time zones for aiports and weather stations are provided by AskGeo.com .