Average Weather in São Tomé São Tomé & Príncipe

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The climate in São Tomé is warm, oppressive, windy, and overcast. Over the course of the year, the temperature typically varies from 75°F to 82°F and is rarely below 73°F or above 84°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.

In São Tomé, 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 São Tomé begins around May 26 and lasts for 6.1 months, ending around November 28. On June 29, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 36% of the time, and overcast or mostly cloudy 64% of the time.

The cloudier part of the year begins around November 28 and lasts for 5.9 months, ending around May 26. On March 23, the cloudiest day of the year, the sky is overcast or mostly cloudy 89% of the time, and clear, mostly clear, or partly cloudy 11% of the time.

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

The wetter season lasts 7.3 months, from October 17 to May 27, with a greater than 33% chance of a given day being a wet day. The chance of a wet day peaks at 64% on March 29.

The drier season lasts 4.7 months, from May 27 to October 17. The smallest chance of a wet day is 1% on August 15.

Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. Based on this categorization, the most common form of precipitation throughout the year is rain alone, with a peak probability of 64% on March 29.

Rainfall

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. São Tomé experiences extreme seasonal variation in monthly rainfall.

The rainy period of the year lasts for 9.0 months, from September 24 to June 23, with a sliding 31-day rainfall of at least 0.5 inches. The most rain falls during the 31 days centered around April 4, with an average total accumulation of 5.4 inches.

The rainless period of the year lasts for 3.0 months, from June 23 to September 24. The least rain falls around August 13, with an average total accumulation of 0.1 inches.

The length of the day in São Tomé does not vary substantially over the course of the year, staying within 8 minutes of 12 hours throughout. In 2017, the shortest day is December 21, with 12 hours, 6 minutes of daylight; the longest day is June 21, with 12 hours, 9 minutes of daylight.

The earliest sunrise is at 5:13 AM on November 3, and the latest sunrise is 31 minutes later at 5:44 AM on February 10. The earliest sunset is at 5:19 PM on November 2, and the latest sunset is 31 minutes later at 5:50 PM on February 11.

Daylight saving time (DST) is not observed in São Tomé during 2017.

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 perceived humidity level in São Tomé, as measured by the percentage of time in which the humidity comfort level is muggy, oppressive, or miserable, does not vary significantly over the course of the year, staying within 1% of 99% throughout.

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 São Tomé experiences mild seasonal variation over the course of the year.

The windier part of the year lasts for 5.9 months, from May 17 to November 14, with average wind speeds of more than 4.9 miles per hour. The windiest day of the year is June 17, with an average hourly wind speed of 5.7 miles per hour.

The calmer time of year lasts for 6.1 months, from November 14 to May 17. The calmest day of the year is January 1, with an average hourly wind speed of 4.2 miles per hour.

The predominant average hourly wind direction in São Tomé varies throughout the year.

The wind is most often from the south for 11 months, from January 29 to December 27, with a peak percentage of 93% on June 22. The wind is most often from the west for 1.1 months, from December 27 to January 29, with a peak percentage of 51% on January 1.

São Tomé 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 3.6 months, from January 24 to May 11, with an average temperature above 83°F. The day of the year with the warmest water is March 23, with an average temperature of 84°F.

The time of year with cooler water lasts for 3.1 months, from June 23 to September 26, with an average temperature below 79°F. The day of the year with the coolest water is August 8, with an average temperature of 77°F.

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 some seasonal variation over the course of the year.

The brighter period of the year lasts for 2.1 months, from August 7 to October 11, with an average daily incident shortwave energy per square meter above 4.9 kWh. The brightest day of the year is September 6, with an average of 5.3 kWh.

The darker period of the year lasts for 2.5 months, from February 28 to May 14, with an average daily incident shortwave energy per square meter below 4.1 kWh. The darkest day of the year is April 11, with an average of 3.7 kWh.

For the purposes of this report, the geographical coordinates of São Tomé are 0.337 deg latitude, 6.727 deg longitude, and 59 ft elevation.

The topography within 2 miles of São Tomé contains only modest variations in elevation, with a maximum elevation change of 404 feet and an average elevation above sea level of 95 feet. Within 10 miles contains only modest variations in elevation (4,662 feet). Within 50 miles also contains extreme variations in elevation (6,657 feet).

The area within 2 miles of São Tomé is covered by cropland (54%), water (24%), and trees (14%), within 10 miles by water (60%) and cropland (16%), and within 50 miles by water (97%).

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

São Tomé is further than 200 kilometers from the nearest reliable weather station, so the weather-related data on this page were taken entirely from NASA's MERRA-2 satellite-era reanalysis . 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.

The temperature and dew point estimates are corrected for the difference between the reference elevation of the MERRA-2 grid cell and the elevation of São Tomé, according to the International Standard Atmosphere .

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.

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.