Average Weather in August in Galveston Texas, United States
In Galveston, the month of August is characterized by essentially constant daily high temperatures, with daily highs around 89°F throughout the month, rarely exceeding 93°F or dropping below 84°F. The highest daily average high temperature is 90°F on August 9.
Daily low temperatures are around 80°F, rarely falling below 75°F or exceeding 83°F. The highest daily average low temperature is 80°F on August 10.
For reference, on August 5, the hottest day of the year, temperatures in Galveston typically range from 80°F to 90°F, while on January 6, the coldest day of the year, they range from 49°F to 61°F.
Average High and Low Temperature in August
The figure below shows you a compact characterization of the hourly average temperatures for the quarter of the year centered on August. 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 August
The month of August in Galveston 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 August 21.
The clearest day of the month is August 31, with clear, mostly clear, or partly cloudy conditions 50% of the time.
For reference, on August 21, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 53%, while on October 26, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 69%.
Cloud Cover in August
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Galveston, the chance of a wet day over the course of August 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 42% on September 4, and its lowest chance is 22% on April 1.
Probability of Precipitation in August
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 August in Galveston is rapidly increasing, starting the month at 3.1 inches, when it rarely exceeds 6.7 inches or falls below 0.6 inches, and ending the month at 4.9 inches, when it rarely exceeds 10.3 inches or falls below 1.1 inches.
The lowest average 31-day accumulation is 3.1 inches on August 1.
Average Monthly Rainfall in August
Over the course of August in Galveston, the length of the day is decreasing. From the start to the end of the month, the length of the day decreases by 46 minutes, implying an average daily decrease of 1 minute, 32 seconds, and weekly decrease of 10 minutes, 41 seconds.
The shortest day of the month is August 31, with 12 hours, 46 minutes of daylight and the longest day is August 1, with 13 hours, 31 minutes of daylight.
Hours of Daylight and Twilight in August
The earliest sunrise of the month in Galveston is 6:39 AM on August 1 and the latest sunrise is 17 minutes later at 6:56 AM on August 31.
The latest sunset is 8:10 PM on August 1 and the earliest sunset is 29 minutes earlier at 7:41 PM on August 31.
Daylight saving time is observed in Galveston during 2017, but it neither starts nor ends during August, so the entire month is in daylight saving time.
For reference, on June 21, the longest day of the year, the Sun rises at 6:20 AM and sets 14 hours, 1 minute later, at 8:21 PM, while on December 21, the shortest day of the year, it rises at 7:09 AM and sets 10 hours, 16 minutes later, at 5:25 PM.
Sunrise & Sunset with Twilight in August
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 Galveston is gradually decreasing during August, falling from 99% to 96% over the course of the month.
For reference, on July 16, the muggiest day of the year, there are muggy conditions 100% of the time, while on January 23, the least muggy day of the year, there are muggy conditions 4% of the time.
Humidity Comfort Levels in August
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 Galveston is essentially constant during August, remaining within 0.1 miles per hour of 4.6 miles per hour throughout.
For reference, on December 25, the windiest day of the year, the daily average wind speed is 6.6 miles per hour, while on August 15, the calmest day of the year, the daily average wind speed is 4.5 miles per hour.
The lowest daily average wind speed during August is 4.5 miles per hour on August 15.
Average Wind Speed in August
Wind Direction in August
Galveston 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 Galveston is essentially constant during August, remaining around 85°F throughout.
The highest average surface water temperature during August is 86°F on August 17.
Average Water Temperature in August
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 Galveston is essentially constant during August, remaining within 0.2 kWh of 5.3 kWh throughout.
Average Daily Incident Shortwave Solar Energy in August
For the purposes of this report, the geographical coordinates of Galveston are 29.301 deg latitude, -94.798 deg longitude, and 3 ft elevation.
The topography within 2 miles of Galveston is essentially flat, with a maximum elevation change of 20 feet and an average elevation above sea level of 5 feet. Within 10 miles is also essentially flat (26 feet). Within 50 miles is essentially flat (112 feet).
The area within 2 miles of Galveston is covered by artificial surfaces (54%), water (25%), and bare soil (11%), within 10 miles by water (80%), and within 50 miles by water (57%) and cropland (19%).
This report illustrates the typical weather in Galveston 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 2 weather stations near enough to contribute to our estimation of the temperature and dew point in Galveston.
For each station, the records are corrected for the elevation difference between that station and Galveston 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 Galveston is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Galveston and a given station.
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.