Summer Weather in Tonga Tonga

Daily high temperatures are around 84°F, rarely falling below 79°F or exceeding 88°F. The highest daily average high temperature is 85°F on February 16.

Daily low temperatures are around 74°F, rarely falling below 69°F or exceeding 78°F. The highest daily average low temperature is 75°F on February 16.

For reference, on February 15, the hottest day of the year, temperatures in Tonga typically range from 75°F to 85°F, while on August 22, the coldest day of the year, they range from 66°F to 76°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.

© OpenStreetMap contributors

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The summer in Tonga experiences gradually increasing cloud cover, with the percentage of time that the sky is overcast or mostly cloudy increasing from 63% to 70%.

The clearest day of the summer is December 3, with clear, mostly clear, or partly cloudy conditions 38% of the time.

For reference, on February 29, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 70%, while on August 8, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 63%.

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Tonga, the chance of a wet day over the course of the summer is very rapidly increasing, starting the season at 28% and ending it at 40%.

For reference, the year's highest daily chance of a wet day is 42% on April 2, and its lowest chance is 15% on June 29.

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 in Tonga is very rapidly increasing, starting the season at 3.7 inches, when it rarely exceeds 7.4 inches or falls below 0.6 inches, and ending the season at 6.4 inches, when it rarely exceeds 11.8 inches or falls below 2.4 inches.

The highest average 31-day accumulation is 6.4 inches on February 21.

Over the course of the summer in Tonga, the length of the day is decreasing. From the start to the end of the season, the length of the day decreases by 46 minutes, implying an average daily decrease of 31 seconds, and weekly decrease of 3 minutes, 39 seconds.

The shortest day of the summer is February 28, with 12 hours, 29 minutes of daylight and the longest day is December 21, with 13 hours, 21 minutes of daylight.

The earliest sunrise of the summer in Tonga is 5:51 AM on December 1 and the latest sunrise is 46 minutes later at 6:37 AM on February 28.

The latest sunset is 7:25 PM on January 16 and the earliest sunset is 19 minutes earlier at 7:06 PM on February 28.

Daylight saving time is not observed in Tonga during 2024.

For reference, on December 21, the longest day of the year, the Sun rises at 5:58 AM and sets 13 hours, 21 minutes later, at 7:18 PM, while on June 20, the shortest day of the year, it rises at 7:14 AM and sets 10 hours, 55 minutes later, at 6:09 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 2024. 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 Tonga is rapidly increasing during the summer, rising from 88% to 99% over the course of the season.

The highest chance of a muggy day during the summer is 100% on February 14.

For reference, on February 13, the muggiest day of the year, there are muggy conditions 100% of the time, while on August 23, the least muggy day of the year, there are muggy conditions 35% 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 Tonga is essentially constant during the summer, remaining within 0.6 miles per hour of 14.1 miles per hour throughout.

For reference, on April 26, the windiest day of the year, the daily average wind speed is 15.4 miles per hour, while on February 17, the calmest day of the year, the daily average wind speed is 13.5 miles per hour.

The highest daily average wind speed during the summer is 14.7 miles per hour on December 15. The lowest daily average wind speed during the summer is 13.5 miles per hour on February 18.

The hourly average wind direction in Tonga throughout the summer is predominantly from the east, with a peak proportion of 72% on December 19.

Tonga 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 Tonga is gradually increasing during the summer, rising by 3°F, from 78°F to 82°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 in Tonga 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 Tonga are very rapidly increasing during the summer, increasing by 2,536°F, from 3,389°F to 5,926°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 Tonga is gradually decreasing during the summer, falling by 0.9 kWh, from 6.6 kWh to 5.8 kWh, over the course of the season.

The highest average daily incident shortwave solar energy during the summer is 6.7 kWh on December 17.

For the purposes of this report, the geographical coordinates of Tonga are -20.000 deg latitude, -175.000 deg longitude, and 0 ft elevation.

The topography within 2 miles of Tonga 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 also essentially flat (0 feet).

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