Fall Weather in Cayman Islands Cayman Islands

Daily high temperatures decrease by 5°F, from 89°F to 84°F, rarely falling below 81°F or exceeding 90°F.

Daily low temperatures are around 78°F, rarely falling below 74°F or exceeding 82°F.

For reference, on August 6, the hottest day of the year, temperatures in Cayman Islands typically range from 81°F to 89°F, while on January 28, the coldest day of the year, they range from 74°F to 82°F.

The figure below shows you a compact characterization of the hourly average fall temperatures. 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.

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The fall in Cayman Islands experiences very rapidly decreasing cloud cover, with the percentage of time that the sky is overcast or mostly cloudy decreasing from 77% to 38%. The highest chance of overcast or mostly cloudy conditions is 79% on September 20.

The clearest day of the fall is November 30, with clear, mostly clear, or partly cloudy conditions 62% of the time.

For reference, on June 15, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 81%, while on February 25, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 82%.

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Cayman Islands, the chance of a wet day over the course of the fall is very rapidly decreasing, starting the season at 28% and ending it at 16%.

For reference, the year's highest daily chance of a wet day is 40% on September 28, and its lowest chance is 3% on April 12.

Rainfall

To show variation within the season and not just the monthly totals, we show the rainfall accumulated over a sliding 31-day period centered around each day.

The average sliding 31-day rainfall during the fall in Cayman Islands is essentially constant, remaining about 3.0 inches throughout, and rarely exceeding 10.1 inches or falling below 0.2 inches.

The highest average 31-day accumulation is 4.2 inches on October 14.

Over the course of the fall in Cayman Islands, the length of the day is rapidly decreasing. From the start to the end of the season, the length of the day decreases by 1 hour, 27 minutes, implying an average daily decrease of 58 seconds, and weekly decrease of 6 minutes, 46 seconds.

The shortest day of the fall is November 30, with 11 hours, 3 minutes of daylight and the longest day is September 1, with 12 hours, 30 minutes of daylight.

The earliest sunrise of the fall in Cayman Islands is 6:07 AM on September 1 and the latest sunrise is 33 minutes later at 6:40 AM on November 30.

The latest sunset is 6:37 PM on September 1 and the earliest sunset is 55 minutes earlier at 5:42 PM on November 25.

Daylight saving time is not observed in Cayman Islands during 2025.

For reference, on June 21, the longest day of the year, the Sun rises at 5:45 AM and sets 13 hours, 19 minutes later, at 7:03 PM, while on December 21, the shortest day of the year, it rises at 6:52 AM and sets 10 hours, 57 minutes later, at 5:49 PM.

The figure below presents a compact representation of the sun's elevation (the angle of the sun above the horizon) and azimuth (its compass bearing) for every hour of every day in the reporting period. The horizontal axis is the day of the year and the vertical axis is the hour of the day. For a given day and hour of that day, the background color indicates the azimuth of the sun at that moment. The black isolines are contours of constant solar elevation.

The figure below presents a compact representation of key lunar data for the fall of 2025. The horizontal axis is the day, the vertical axis is the hour of the day, and the colored areas indicate when the moon is above the horizon. The vertical gray bars (new Moons) and blue bars (full Moons) indicate key Moon phases. The label associated with each bar indicates the date and time that the phase is obtained, and the companion time labels indicate the rise and set times of the Moon for the nearest time interval in which the moon is above the horizon.

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 Cayman Islands is gradually decreasing during the fall, falling from 100% to 97% over the course of the season.

For reference, on May 23, the muggiest day of the year, there are muggy conditions 100% of the time, while on January 15, the least muggy day of the year, there are muggy conditions 90% of the time.

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 Cayman Islands is very rapidly increasing during the fall, increasing from 10.9 miles per hour to 15.5 miles per hour over the course of the season.

For reference, on November 26, the windiest day of the year, the daily average wind speed is 15.7 miles per hour, while on September 11, the calmest day of the year, the daily average wind speed is 10.7 miles per hour.

The lowest daily average wind speed during the fall is 10.7 miles per hour on September 11.

The hourly average wind direction in Cayman Islands throughout the fall is predominantly from the east, with a peak proportion of 85% on September 1.

Cayman Islands 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 Cayman Islands is gradually decreasing during the fall, falling by 3°F, from 85°F to 82°F, over the course of the season.

The highest average surface water temperature during the fall is 85°F on September 10.

Definitions of the growing season vary throughout the world, but for the purposes of this report, we define it as the longest continuous period of non-freezing temperatures (≥ 32°F) in the year (the calendar year in the Northern Hemisphere, or from July 1 until June 30 in the Southern Hemisphere).

Temperatures in Cayman Islands are sufficiently warm year round that it is not entirely meaningful to discuss the growing season in these terms. We nevertheless include the chart below as an illustration of the distribution of temperatures experienced throughout the year.

Growing degree days are a measure of yearly heat accumulation used to predict plant and animal development, and defined as the integral of warmth above a base temperature, discarding any excess above a maximum temperature. In this report, we use a base of 50°F and a cap of 86°F.

The average accumulated growing degree days in Cayman Islands are very rapidly increasing during the fall, increasing by 2,902°F, from 7,582°F to 10,483°F, over the course of the season.

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 Cayman Islands is essentially constant during the fall, remaining within 0.2 kWh of 4.3 kWh throughout.

The lowest average daily incident shortwave solar energy during the fall is 4.1 kWh on September 22.

For the purposes of this report, the geographical coordinates of Cayman Islands are 19.500 deg latitude, -80.667 deg longitude, and 20 ft elevation.

The topography within 2 miles of Cayman Islands is essentially flat, with a maximum elevation change of 0 feet and an average elevation above sea level of 0 feet. Within 10 miles is also essentially flat (0 feet). Within 50 miles is essentially flat (115 feet).

The area within 2 miles of Cayman Islands is covered by water (100%), within 10 miles by water (100%), and within 50 miles by water (99%).