Average Weather in July in Key West Florida, United States
In Key West, the month of July is characterized by essentially constant daily high temperatures, with daily highs around 88°F throughout the month, rarely exceeding 91°F or dropping below 85°F.
Daily low temperatures are around 81°F, rarely falling below 76°F or exceeding 84°F.
For reference, on August 7, the hottest day of the year, temperatures in Key West typically range from 81°F to 89°F, while on January 18, the coldest day of the year, they range from 65°F to 74°F.
Average High and Low Temperature in July
The figure below shows you a compact characterization of the hourly average temperatures for the quarter of the year centered on July. 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 July
The month of July in Key West experiences gradually decreasing cloud cover, with the percentage of time that the sky is overcast or mostly cloudy decreasing from 69% to 64%.
The clearest day of the month is July 22, with clear, mostly clear, or partly cloudy conditions 38% of the time.
For reference, on June 20, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 70%, while on March 6, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 73%.
Cloud Cover in July
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Key West, the chance of a wet day over the course of July is essentially constant, remaining around 51% throughout.
For reference, the year's highest daily chance of a wet day is 59% on September 16, and its lowest chance is 12% on March 20.
Probability of Precipitation in July
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 July in Key West is decreasing, starting the month at 4.9 inches, when it rarely exceeds 9.3 inches or falls below 1.4 inches, and ending the month at 4.3 inches, when it rarely exceeds 7.9 inches or falls below 1.4 inches.
The lowest average 31-day accumulation is 4.2 inches on July 25.
Average Monthly Rainfall in July
Over the course of July in Key West, the length of the day is gradually decreasing. From the start to the end of the month, the length of the day decreases by 22 minutes, implying an average daily decrease of 43 seconds, and weekly decrease of 5 minutes, 2 seconds.
The shortest day of the month is July 31, with 13 hours, 16 minutes of daylight and the longest day is July 1, with 13 hours, 38 minutes of daylight.
Hours of Daylight and Twilight in July
The earliest sunrise of the month in Key West is 6:42 AM on July 1 and the latest sunrise is 13 minutes later at 6:55 AM on July 31.
The latest sunset is 8:20 PM on July 2 and the earliest sunset is 9 minutes earlier at 8:11 PM on July 31.
Daylight saving time is observed in Key West during 2017, but it neither starts nor ends during July, so the entire month is in daylight saving time.
For reference, on June 21, the longest day of the year, the Sun rises at 6:39 AM and sets 13 hours, 40 minutes later, at 8:18 PM, while on December 21, the shortest day of the year, it rises at 7:06 AM and sets 10 hours, 37 minutes later, at 5:43 PM.
Sunrise & Sunset with Twilight in July
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 Key West is essentially constant during July, remaining around 100% throughout.
For reference, on July 3, the muggiest day of the year, there are muggy conditions 100% of the time, while on January 29, the least muggy day of the year, there are muggy conditions 42% of the time.
Humidity Comfort Levels in July
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 Key West is essentially constant during July, remaining within 0.1 miles per hour of 5.1 miles per hour throughout.
For reference, on November 7, the windiest day of the year, the daily average wind speed is 7.9 miles per hour, while on July 29, the calmest day of the year, the daily average wind speed is 5.0 miles per hour.
Average Wind Speed in July
Wind Direction in July
Key West 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 Key West is essentially constant during July, remaining within 1°F of 85°F throughout.
Average Water Temperature in July
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 Key West is essentially constant during July, remaining within 0.1 kWh of 4.9 kWh throughout.
Average Daily Incident Shortwave Solar Energy in July
For the purposes of this report, the geographical coordinates of Key West are 24.555 deg latitude, -81.782 deg longitude, and 0 ft elevation.
The topography within 2 miles of Key West is essentially flat, with a maximum elevation change of 10 feet and an average elevation above sea level of 2 foot. Within 10 miles is also essentially flat (10 feet). Within 50 miles is also essentially flat (16 feet).
The area within 2 miles of Key West is covered by water (59%) and artificial surfaces (37%), within 10 miles by water (95%), and within 50 miles by water (99%).
This report illustrates the typical weather in Key West 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 is only a single weather station, Key West International Airport, in our network suitable to be used as a proxy for the historical temperature and dew point records of Key West.
At a distance of 3 kilometers from Key West, closer than our threshold of 150 kilometers, this station is deemed sufficiently nearby to be relied upon as our primary source for temperature and dew point records.
The station records are corrected for the elevation difference between the station and Key West according to the International Standard Atmosphere , and by the relative change present in the MERRA-2 satellite-era reanalysis between the two locations.
Please note that the station records themselves may additionally have been back-filled using other nearby stations or the MERRA-2 reanalysis.
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.