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Climate and Average Weather Year Round in Tonga Tonga

In Tonga, the summers are warm, oppressive, and overcast; the winters are comfortable, humid, and partly cloudy; and it is wet and windy year round. Over the course of the year, the temperature typically varies from 66°F to 85°F and is rarely below 60°F or above 88°F.

Based on the tourism score, the best time of year to visit Tonga for warm-weather activities is from early May to early November.

Climate in Tonga

warmJanFebMarAprMayJunJulAugSepOctNovDecNowNow63%63%29%29%overcastclearprecipitation: 6.4 inprecipitation: 6.4 in1.9 in1.9 inmuggy: 100%muggy: 100%35%35%tourism score: 7.6tourism score: 7.64.84.8
Tonga weather by month. Click on each chart for more information.

The warm season lasts for 3.5 months, from December 23 to April 6, with an average daily high temperature above 83°F. The hottest month of the year in Tonga is February, with an average high of 85°F and low of 75°F.

The cool season lasts for 3.6 months, from June 12 to September 30, with an average daily high temperature below 78°F. The coldest month of the year in Tonga is August, with an average low of 66°F and high of 76°F.

Average High and Low Temperature in Tonga

Average High and Low Temperature in TongawarmcoolJanFebMarAprMayJunJulAugSepOctNovDec0°F0°F10°F10°F20°F20°F30°F30°F40°F40°F50°F50°F60°F60°F70°F70°F80°F80°F90°F90°F100°F100°FAug 2376°FAug 2376°FFeb 1585°FFeb 1585°F66°F66°F75°F75°FDec 2383°FDec 2383°FApr 683°FApr 683°FJun 1278°FJun 1278°FSep 3078°FSep 3078°F74°F74°F74°F74°F69°F69°F68°F68°FNowNow
The daily average high (red line) and low (blue line) temperature, with 25th to 75th and 10th to 90th percentile bands. The thin dotted lines are the corresponding average perceived temperatures.
AverageJanFebMarAprMayJunJulAugSepOctNovDec
High84°F85°F84°F82°F79°F77°F76°F76°F77°F79°F81°F83°F
Temp.79°F80°F79°F77°F74°F72°F71°F70°F71°F73°F75°F78°F
Low75°F75°F75°F73°F70°F68°F67°F66°F67°F69°F71°F73°F

The figure below shows you a compact characterization of the entire year of hourly average temperatures. The horizontal axis is the day of the year, 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 Tonga

Average Hourly Temperature in TongaJanFebMarAprMayJunJulAugSepOctNovDec12 AM12 AM2 AM2 AM4 AM4 AM6 AM6 AM8 AM8 AM10 AM10 AM12 PM12 PM2 PM2 PM4 PM4 PM6 PM6 PM8 PM8 PM10 PM10 PM12 AM12 AMNowNowcomfortablewarmwarmwarm
frigid 15°F freezing 32°F very cold 45°F cold 55°F cool 65°F comfortable 75°F warm 85°F hot 95°F sweltering
The average hourly temperature, color coded into bands. The shaded overlays indicate night and civil twilight.
Map
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© Esri, et al.

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In Tonga, the average percentage of the sky covered by clouds experiences significant seasonal variation over the course of the year.

The clearer part of the year in Tonga begins around May 5 and lasts for 5.8 months, ending around October 30.

The clearest month of the year in Tonga is August, during which on average the sky is clear, mostly clear, or partly cloudy 61% of the time.

The cloudier part of the year begins around October 30 and lasts for 6.2 months, ending around May 5.

The cloudiest month of the year in Tonga is February, during which on average the sky is overcast or mostly cloudy 70% of the time.

Cloud Cover Categories in Tonga

Cloud Cover Categories in TongaclearercloudiercloudierJanFebMarAprMayJunJulAugSepOctNovDec0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%Aug 963%Aug 963%Mar 129%Mar 129%May 546%May 546%Oct 3047%Oct 3047%NowNowclearmostly clearpartly cloudyovercast
0% clear 20% mostly clear 40% partly cloudy 60% mostly cloudy 80% overcast 100%
The percentage of time spent in each cloud cover band, categorized by the percentage of the sky covered by clouds.
FractionJanFebMarAprMayJunJulAugSepOctNovDec
Cloudier68%70%68%61%53%47%39%39%42%49%61%64%
Clearer32%30%32%39%47%53%61%61%58%51%39%36%

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in Tonga varies throughout the year.

The wetter season lasts 4.7 months, from December 6 to April 28, with a greater than 29% chance of a given day being a wet day. The month with the most wet days in Tonga is February, with an average of 11.2 days with at least 0.04 inches of precipitation.

The drier season lasts 7.3 months, from April 28 to December 6. The month with the fewest wet days in Tonga is July, with an average of 5.7 days with at least 0.04 inches of precipitation.

Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. The month with the most days of rain alone in Tonga is February, with an average of 11.2 days. Based on this categorization, the most common form of precipitation throughout the year is rain alone, with a peak probability of 42% on April 3.

Daily Chance of Precipitation in Tonga

Daily Chance of Precipitation in TongawetwetdryJanFebMarAprMayJunJulAugSepOctNovDec0%0%10%10%20%20%30%30%40%40%50%50%60%60%70%70%80%80%90%90%100%100%Apr 342%Apr 342%Jun 3015%Jun 3015%Jan 128%Jan 128%NowNowrain
The percentage of days in which various types of precipitation are observed, excluding trace quantities: rain alone, snow alone, and mixed (both rain and snow fell in the same day).
Days ofJanFebMarAprMayJunJulAugSepOctNovDec
Rain9.9d11.2d12.3d10.1d7.5d6.3d5.7d6.9d6.6d6.6d7.0d8.5d

To show variation within the months and not just the monthly totals, we show the rainfall accumulated over a sliding 31-day period centered around each day of the year. Tonga experiences extreme seasonal variation in monthly rainfall.

Rain falls throughout the year in Tonga. The month with the most rain in Tonga is February, with an average rainfall of 6.3 inches.

The month with the least rain in Tonga is July, with an average rainfall of 2.0 inches.

Average Monthly Rainfall in Tonga

Average Monthly Rainfall in TongaJanFebMarAprMayJunJulAugSepOctNovDec0 in0 in2 in2 in4 in4 in6 in6 in8 in8 in10 in10 in12 in12 in14 in14 inFeb 216.4 inFeb 216.4 inJul 101.9 inJul 101.9 inAug 202.7 inAug 202.7 inOct 252.2 inOct 252.2 inNowNow
The average rainfall (solid line) accumulated over the course of a sliding 31-day period centered on the day in question, with 25th to 75th and 10th to 90th percentile bands. The thin dotted line is the corresponding average snowfall.
JanFebMarAprMayJunJulAugSepOctNovDec
Rainfall5.1″6.3″6.2″5.7″3.4″2.7″2.0″2.6″2.6″2.3″3.0″3.9″

The length of the day in Tonga varies over the course of the year. In 2021, the shortest day is June 21, with 10 hours, 55 minutes of daylight; the longest day is December 22, with 13 hours, 21 minutes of daylight.

Hours of Daylight and Twilight in Tonga

The number of hours during which the Sun is visible (black line). From bottom (most yellow) to top (most gray), the color bands indicate: full daylight, twilight (civil, nautical, and astronomical), and full night.
Hours ofJanFebMarAprMayJunJulAugSepOctNovDec
Daylight13.2h12.7h12.2h11.6h11.1h10.9h11.1h11.5h12.0h12.6h13.1h13.3h

The earliest sunrise is at 5:51 AM on November 26, and the latest sunrise is 1 hour, 25 minutes later at 7:15 AM on July 6. The earliest sunset is at 6:07 PM on June 5, and the latest sunset is 1 hour, 18 minutes later at 7:25 PM on January 15.

Daylight saving time (DST) is not observed in Tonga during 2021.

Sunrise & Sunset with Twilight in Tonga

Sunrise & Sunset with Twilight in TongaJanFebMarAprMayJunJulAugSepOctNovDec2 AM4 AM6 AM8 AM10 AM12 PM2 PM4 PM6 PM8 PM10 PM12 AMNov 265:51 AMNov 265:51 AM7:25 PMJan 157:25 PMJan 15Jun 56:07 PMJun 56:07 PM7:15 AMJul 67:15 AMJul 6daySolarMidnightSolarMidnightSolarNoonSunriseSunsetNowNow
The solar day over the course of the year 2021. From bottom to top, the black lines are the previous solar midnight, sunrise, solar noon, sunset, and the next solar midnight. The day, twilights (civil, nautical, and astronomical), and night are indicated by the color bands from yellow to gray.

The figure below presents a compact representation of key lunar data for 2021. 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.

Moon Rise, Set & Phases in Tonga

The time in which the moon is above the horizon (light blue area), with new moons (dark gray lines) and full moons (blue lines) indicated. The shaded overlays indicate night and civil twilight.

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.

Tonga experiences extreme seasonal variation in the perceived humidity.

The muggier period of the year lasts for 8.5 months, from October 8 to June 23, during which time the comfort level is muggy, oppressive, or miserable at least 51% of the time. The month with the most muggy days in Tonga is January, with 30.4 days that are muggy or worse.

The month with the fewest muggy days in Tonga is August, with 11.5 days that are muggy or worse.

Humidity Comfort Levels in Tonga

Humidity Comfort Levels in TongamuggymuggyJanFebMarAprMayJunJulAugSepOctNovDec0%0%10%10%20%20%30%30%40%40%50%50%60%60%70%70%80%80%90%90%100%100%Aug 2435%Aug 2435%100%Feb 14100%Feb 14Oct 851%Oct 851%Jun 2351%Jun 2351%NowNowmiserablemiserableoppressiveoppressivemuggymuggyhumidhumidcomfortablecomfortabledrydry
dry 55°F comfortable 60°F humid 65°F muggy 70°F oppressive 75°F miserable
The percentage of time spent at various humidity comfort levels, categorized by dew point.
JanFebMarAprMayJunJulAugSepOctNovDec
Muggy days30.4d27.8d30.4d27.2d22.0d16.6d12.2d11.5d13.5d18.0d23.8d28.8d

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 experiences mild seasonal variation over the course of the year.

The windier part of the year lasts for 2.6 months, from April 3 to June 22, with average wind speeds of more than 14.5 miles per hour. The windiest month of the year in Tonga is April, with an average hourly wind speed of 15.0 miles per hour.

The calmer time of year lasts for 9.4 months, from June 22 to April 3. The calmest month of the year in Tonga is February, with an average hourly wind speed of 13.7 miles per hour.

Average Wind Speed in Tonga

Average Wind Speed in TongawindyJanFebMarAprMayJunJulAugSepOctNovDec0 mph0 mph2 mph2 mph4 mph4 mph6 mph6 mph8 mph8 mph10 mph10 mph12 mph12 mph14 mph14 mph16 mph16 mph18 mph18 mph20 mph20 mph22 mph22 mphApr 2715.4 mphApr 2715.4 mphFeb 1713.5 mphFeb 1713.5 mphJun 2214.5 mphJun 2214.5 mphNowNow
The average of mean hourly wind speeds (dark gray line), with 25th to 75th and 10th to 90th percentile bands.
JanFebMarAprMayJunJulAugSepOctNovDec
Wind Speed (mph)14.113.714.015.014.814.514.614.614.314.314.014.4

The predominant average hourly wind direction in Tonga is from the east throughout the year.

Wind Direction in Tonga

Wind Direction in TongaJanFebMarAprMayJunJulAugSepOctNovDec0%100%20%80%40%60%60%40%80%20%100%0%NowNowsoutheastnorthwest
northeastsouthwest
The percentage of hours in which the mean wind direction is from each of the four cardinal wind directions, excluding hours in which the mean wind speed is less than 1.0 mph. The lightly tinted areas at the boundaries are the percentage of hours spent in the implied intermediate directions (northeast, southeast, southwest, and northwest).

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 water temperature experiences some seasonal variation over the course of the year.

The time of year with warmer water lasts for 3.5 months, from January 6 to April 21, with an average temperature above 80°F. The month of the year in Tonga with the warmest water is February, with an average temperature of 81°F.

The time of year with cooler water lasts for 3.4 months, from July 8 to October 21, with an average temperature below 76°F. The month of the year in Tonga with the coolest water is August, with an average temperature of 74°F.

Average Water Temperature in Tonga

Average Water Temperature in TongawarmcoolJanFebMarAprMayJunJulAugSepOctNovDec72°F72°F74°F74°F76°F76°F78°F78°F80°F80°F82°F82°F84°F84°FFeb 2682°FFeb 2682°F74°FAug 2774°FAug 27Jan 680°FJan 680°FApr 2180°FApr 2180°FJul 876°FJul 876°FOct 2176°FOct 2176°FNowNow
The daily average water temperature (purple line), with 25th to 75th and 10th to 90th percentile bands.
WaterJanFebMarAprMayJunJulAugSepOctNovDec
Temperature80°F81°F81°F80°F78°F77°F75°F74°F74°F76°F77°F79°F

To characterize how pleasant the weather is in Tonga throughout the year, we compute two travel scores.

The tourism score favors clear, rainless days with perceived temperatures between 65°F and 80°F. Based on this score, the best time of year to visit Tonga for general outdoor tourist activities is from early May to early November, with a peak score in the last week of July.

Tourism Score in Tonga

Tourism Score in Tongabest timeJanFebMarAprMayJunJulAugSepOctNovDec002244668810107.67.64.84.8NowNowprecipitationprecipitationcloudscloudstemperaturetemperature tourism score
The tourism score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).

The beach/pool score favors clear, rainless days with perceived temperatures between 75°F and 90°F. Based on this score, the best times of year to visit Tonga for hot-weather activities are from early March to early June and from mid October to mid February, with a peak score in the first week of May.

Beach/Pool Score in Tonga

Beach/Pool Score in Tongabest timebest timeJanFebMarAprMayJunJulAugSepOctNovDec002244668810106.16.14.34.3NowNowprecipitationprecipitationcloudscloudstemperaturetemperature beach/pool score
The beach/pool score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).

Methodology

For each hour between 8:00 AM and 9:00 PM of each day in the analysis period (1980 to 2016), independent scores are computed for perceived temperature, cloud cover, and total precipitation. Those scores are combined into a single hourly composite score, which is then aggregated into days, averaged over all the years in the analysis period, and smoothed.

Our cloud cover score is 10 for fully clear skies, falling linearly to 9 for mostly clear skies, and to 1 for fully overcast skies.

Our precipitation score, which is based on the three-hour precipitation centered on the hour in question, is 10 for no precipitation, falling linearly to 9 for trace precipitation, and to 0 for 0.04 inches of precipitation or more.

Our tourism temperature score is 0 for perceived temperatures below 50°F, rising linearly to 9 for 65°F, to 10 for 75°F, falling linearly to 9 for 80°F, and to 1 for 90°F or hotter.

Our beach/pool temperature score is 0 for perceived temperatures below 65°F, rising linearly to 9 for 75°F, to 10 for 82°F, falling linearly to 9 for 90°F, and to 1 for 100°F or hotter.

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.

Time Spent in Various Temperature Bands and the Growing Season in Tonga

Time Spent in Various Temperature Bands and the Growing Season in TongaJanFebMarAprMayJunJulAugSepOctNovDec0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%100%Jan 1100%Jan 1100%Jul 3100%Jul 3NowNowcomfortablewarmhotcool
frigid 15°F freezing 32°F very cold 45°F cold 55°F cool 65°F comfortable 75°F warm 85°F hot 95°F sweltering
The percentage of time spent in various temperature bands. The black line is the percentage chance that a given day is within the growing season.

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.

Growing Degree Days in Tonga

Growing Degree Days in TongaJanFebMarAprMayJunJulAugSepOctNovDec0°F0°F1,000°F1,000°F2,000°F2,000°F3,000°F3,000°F4,000°F4,000°F5,000°F5,000°F6,000°F6,000°F7,000°F7,000°F8,000°F8,000°F9,000°F9,000°FJul 590°FJul 590°FAug 14900°FAug 14900°FSep 261,800°FSep 261,800°FJun 309,086°FJun 309,086°FNowNow
The average growing degree days accumulated over the course of the year, with 25th to 75th and 10th to 90th percentile bands.

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 experiences significant seasonal variation over the course of the year.

The brighter period of the year lasts for 4.0 months, from October 10 to February 10, with an average daily incident shortwave energy per square meter above 6.1 kWh. The brightest month of the year in Tonga is December, with an average of 6.7 kWh.

The darker period of the year lasts for 2.9 months, from May 8 to August 6, with an average daily incident shortwave energy per square meter below 4.2 kWh. The darkest month of the year in Tonga is June, with an average of 3.6 kWh.

Average Daily Incident Shortwave Solar Energy in Tonga

Average Daily Incident Shortwave Solar Energy in TongabrightbrightdarkJanFebMarAprMayJunJulAugSepOctNovDec0 kWh0 kWh1 kWh1 kWh2 kWh2 kWh3 kWh3 kWh4 kWh4 kWh5 kWh5 kWh6 kWh6 kWh7 kWh7 kWh8 kWh8 kWh9 kWh9 kWhDec 176.7 kWhDec 176.7 kWhJun 153.6 kWhJun 153.6 kWhOct 106.1 kWhOct 106.1 kWhFeb 106.1 kWhFeb 106.1 kWhMay 84.2 kWhMay 84.2 kWhAug 64.2 kWhAug 64.2 kWhNowNow
The average daily shortwave solar energy reaching the ground per square meter (orange line), with 25th to 75th and 10th to 90th percentile bands.
JanFebMarAprMayJunJulAugSepOctNovDec
Solar Energy (kWh)6.56.05.44.74.03.63.84.55.46.26.56.7

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%).

This report illustrates the typical weather in Tonga, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016.

The details of the data sources used for this report can be found on the Fuaʻamotu International Airport page.

Disclaimer

The information on this site is provided as is, without any assurances as to its accuracy or suitability for any purpose. Weather data is prone to errors, outages, and other defects. We assume no responsibility for any decisions made on the basis of the content presented on this site.

We draw particular cautious attention to our reliance on the MERRA-2 model-based reconstructions for a number of important data series. While having the tremendous advantages of temporal and spatial completeness, these reconstructions: (1) are based on computer models that may have model-based errors, (2) are coarsely sampled on a 50 km grid and are therefore unable to reconstruct the local variations of many microclimates, and (3) have particular difficulty with the weather in some coastal areas, especially small islands.

We further caution that our travel scores are only as good as the data that underpin them, that weather conditions at any given location and time are unpredictable and variable, and that the definition of the scores reflects a particular set of preferences that may not agree with those of any particular reader.

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