Average Weather in May in Roanoke Alabama, United States
In Roanoke, the month of May is characterized by rising daily high temperatures, with daily highs increasing by 7°F, from 77°F to 84°F over the course of the month, and rarely exceeding 90°F or dropping below 68°F.
Daily low temperatures increase by 9°F, from 55°F to 64°F, rarely falling below 45°F or exceeding 69°F.
For reference, on July 23, the hottest day of the year, temperatures in Roanoke typically range from 71°F to 89°F, while on January 24, the coldest day of the year, they range from 36°F to 54°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 Roanoke experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 42% throughout the month. The lowest chance of overcast or mostly cloudy conditions is 40% on May 1.
The clearest day of the month is May 1, with clear, mostly clear, or partly cloudy conditions 60% of the time.
For reference, on January 4, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 54%, while on October 8, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 67%.
Cloud Cover in May
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Roanoke, the chance of a wet day over the course of May is increasing, starting the month at 29% and ending it at 34%.
For reference, the year's highest daily chance of a wet day is 46% on July 9, and its lowest chance is 19% on October 15.
Probability of Precipitation in May
To show variation within the month and not just the monthly total, we show the rainfall accumulated over a sliding 31-day period centered around each day.
The average sliding 31-day rainfall during May in Roanoke is gradually decreasing, starting the month at 3.5 inches, when it rarely exceeds 6.1 inches or falls below 1.1 inches, and ending the month at 3.1 inches, when it rarely exceeds 5.7 inches or falls below 1.2 inches.
The lowest average 31-day accumulation is 3.1 inches on May 27.
Average Monthly Rainfall in May
Over the course of May in Roanoke, the length of the day is increasing. From the start to the end of the month, the length of the day increases by 41 minutes, implying an average daily increase of 1 minute, 22 seconds, and weekly increase of 9 minutes, 33 seconds.
The shortest day of the month is May 1, with 13 hours, 31 minutes of daylight and the longest day is May 31, with 14 hours, 12 minutes of daylight.
Hours of Daylight and Twilight in May
The latest sunrise of the month in Roanoke is 5:53 AM on May 1 and the earliest sunrise is 20 minutes earlier at 5:33 AM on May 31.
The earliest sunset is 7:24 PM on May 1 and the latest sunset is 21 minutes later at 7:45 PM on May 31.
Daylight saving time is observed in Roanoke during 2017, 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 5:32 AM and sets 14 hours, 21 minutes later, at 7:53 PM, while on December 21, the shortest day of the year, it rises at 6:40 AM and sets 9 hours, 58 minutes later, at 4:38 PM.
Sunrise & Sunset with Twilight in May
We base the humidity comfort level on the dew point, as it determines whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid. Unlike temperature, which typically varies significantly between night and day, dew point tends to change more slowly, so while the temperature may drop at night, a muggy day is typically followed by a muggy night.
The chance that a given day will be muggy in Roanoke is very rapidly increasing during May, rising from 12% to 51% over the course of the month.
For reference, on July 24, the muggiest day of the year, there are muggy conditions 93% of the time, while on January 16, the least muggy day of the year, there are muggy conditions 0% of the time.
Humidity Comfort Levels in May
This section discusses the wide-area hourly average wind vector (speed and direction) at 10 meters above the ground. The wind experienced at any given location is highly dependent on local topography and other factors, and instantaneous wind speed and direction vary more widely than hourly averages.
The average hourly wind speed in Roanoke is essentially constant during May, remaining within 0.2 miles per hour of 2.1 miles per hour throughout.
For reference, on February 26, the windiest day of the year, the daily average wind speed is 2.7 miles per hour, while on August 5, the calmest day of the year, the daily average wind speed is 1.6 miles per hour.
Average Wind Speed in May
Wind Direction in May
This section discusses the total daily incident shortwave solar energy reaching the surface of the ground over a wide area, taking full account of seasonal variations in the length of the day, the elevation of the Sun above the horizon, and absorption by clouds and other atmospheric constituents. Shortwave radiation includes visible light and ultraviolet radiation.
The average daily incident shortwave solar energy in Roanoke is essentially constant during May, remaining within 0.1 kWh of 6.6 kWh throughout.
The highest average daily incident shortwave solar energy during May is 6.7 kWh on May 20.
Average Daily Incident Shortwave Solar Energy in May
For the purposes of this report, the geographical coordinates of Roanoke are 33.151 deg latitude, -85.372 deg longitude, and 823 ft elevation.
The topography within 2 miles of Roanoke contains only modest variations in elevation, with a maximum elevation change of 207 feet and an average elevation above sea level of 815 feet. Within 10 miles contains only modest variations in elevation (784 feet). Within 50 miles contains significant variations in elevation (2,172 feet).
The area within 2 miles of Roanoke is covered by trees (42%), cropland (41%), and artificial surfaces (17%), within 10 miles by trees (80%) and cropland (18%), and within 50 miles by trees (80%) and cropland (13%).
This report illustrates the typical weather in Roanoke 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 Roanoke.
For each station, the records are corrected for the elevation difference between that station and Roanoke 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 Roanoke is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Roanoke and a given station.
The stations contributing to this reconstruction are: La Grange, Callaway Airport (39%, 32 kilometers, southeast); West Georgia Regional Airport - O V Gray Field (16%, 57 kilometers, north); Auburn-Opelika Robert G Pitts Airport (16%, 60 kilometers, south); Thomas C Russell Field (15%, 61 kilometers, southwest); and Anniston Metropolitan Airport (13%, 66 kilometers, northwest).
All data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Tables of the Sun, Moon and Planets , by Jean Meeus.
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.
Land Use data comes from the Global Land Cover SHARE database , published by the Food and Agriculture Organization of the United Nations.
Elevation data comes from the Shuttle Radar Topography Mission (SRTM) , published by NASA's Jet Propulsion Laboratory.
Names, locations, and time zones of places and some airports come from the GeoNames Geographical Database .
Time zones for aiports and weather stations are provided by AskGeo.com .
Maps are © Esri, with data from National Geographic, Esri, DeLorme, NAVTEQ, UNEP-WCMC, USGS, NASA, ESA, METI, NRCAN, GEBCO, NOAA, and iPC.