Summer Weather at Gough Island St. Helena

Daily high temperatures are around 62°F, rarely falling below 55°F or exceeding 70°F. The highest daily average high temperature is 64°F on January 29.

Daily low temperatures are around 53°F, rarely falling below 47°F or exceeding 60°F.

For reference, on January 22, the hottest day of the year, temperatures at Gough Island typically range from 55°F to 64°F, while on August 21, the coldest day of the year, they range from 46°F to 52°F.

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

Port Orford, Oregon, United States (9,149 miles away) and Vilaflor, Spain (4,758 miles) are the far-away foreign places with temperatures most similar to Gough Island (view comparison).

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The summer at Gough Island experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 63% throughout the season. The highest chance of overcast or mostly cloudy conditions is 65% on December 9. The lowest chance of overcast or mostly cloudy conditions is 60% on February 8.

The clearest day of the summer is February 8, with clear, mostly clear, or partly cloudy conditions 40% of the time.

For reference, on June 12, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 66%, while on September 17, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 40%.

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. At Gough Island, the chance of a wet day over the course of the summer is gradually decreasing, starting the season at 34% and ending it at 30%.

For reference, the year's highest daily chance of a wet day is 46% on June 7, and its lowest chance is 26% on February 8.

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 summer at Gough Island is essentially constant, remaining about 2.5 inches throughout, and rarely exceeding 4.2 inches or falling below 1.2 inches.

The lowest average 31-day accumulation is 2.2 inches on February 8.

Over the course of the summer at Gough Island, 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, 46 minutes, implying an average daily decrease of 1 minute, 12 seconds, and weekly decrease of 8 minutes, 22 seconds.

The shortest day of the summer is February 28, with 13 hours, 3 minutes of daylight and the longest day is December 21, with 15 hours, 3 minutes of daylight.

The earliest sunrise of the summer at Gough Island is 5:02 AM on December 8 and the latest sunrise is 1 hour, 17 minutes later at 6:20 AM on February 28.

The latest sunset is 8:12 PM on January 4 and the earliest sunset is 50 minutes earlier at 7:23 PM on February 28.

Daylight saving time is not observed at Gough Island during 2026.

For reference, on December 21, the longest day of the year, the Sun rises at 5:05 AM and sets 15 hours, 3 minutes later, at 8:09 PM, while on June 21, the shortest day of the year, it rises at 8:02 AM and sets 9 hours, 17 minutes later, at 5:20 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 summer of 2026. 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 at Gough Island is essentially constant during the summer, remaining within 1% of 1% throughout.

The highest chance of a muggy day during the summer is 2% on February 15.

For reference, on February 14, the muggiest day of the year, there are muggy conditions 2% of the time, while on May 5, the least muggy day of the year, there are muggy conditions 0% 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 at Gough Island is essentially constant during the summer, remaining within 0.6 miles per hour of 17.8 miles per hour throughout.

For reference, on July 27, the windiest day of the year, the daily average wind speed is 22.6 miles per hour, while on February 5, the calmest day of the year, the daily average wind speed is 17.2 miles per hour.

The lowest daily average wind speed during the summer is 17.2 miles per hour on February 7.

The hourly average wind direction at Gough Island throughout the summer is predominantly from the west, with a peak proportion of 61% on January 2.

Gough Island 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 at Gough Island is increasing during the summer, rising by 4°F, from 54°F to 58°F, over the course of the season.

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 at Gough Island 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 at Gough Island are rapidly increasing during the summer, increasing by 740°F, from 382°F to 1,121°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 at Gough Island is decreasing during the summer, falling by 1.1 kWh, from 6.1 kWh to 5.0 kWh, over the course of the season.

The highest average daily incident shortwave solar energy during the summer is 6.5 kWh on December 29.

For the purposes of this report, the geographical coordinates of Gough Island are -40.350 deg latitude, -9.883 deg longitude, and 171 ft elevation.

The topography within 2 miles of Gough Island contains large variations in elevation, with a maximum elevation change of 2,425 feet and an average elevation above sea level of 381 feet. Within 10 miles also contains large variations in elevation (2,969 feet). Within 50 miles also contains large variations in elevation (2,969 feet).

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