Average Weather in Santo António São Tomé & Príncipe

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2. São Tomé & Príncipe
3. Príncipe
4. Santo António

The climate in Santo António is warm, oppressive, windy, and overcast. Over the course of the year, the temperature typically varies from 75°F to 81°F and is rarely below 74°F or above 83°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 Santo António, the average percentage of the sky covered by clouds experiences mild seasonal variation over the course of the year.

The clearer part of the year in Santo António begins around October 21 and lasts for 4.4 months, ending around March 3. On December 27, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 25% of the time, and overcast or mostly cloudy 75% of the time.

The cloudier part of the year begins around March 3 and lasts for 7.6 months, ending around October 21. On April 28, the cloudiest day of the year, the sky is overcast or mostly cloudy 90% of the time, and clear, mostly clear, or partly cloudy 9% 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 Santo António varies very significantly throughout the year.

The wetter season lasts 8.3 months, from September 26 to June 6, with a greater than 46% chance of a given day being a wet day. The chance of a wet day peaks at 78% on October 26.

The drier season lasts 3.7 months, from June 6 to September 26. The smallest chance of a wet day is 12% on July 31.

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 78% on October 26.

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. Santo António experiences extreme seasonal variation in monthly rainfall.

Rain falls throughout the year in Santo António. The most rain falls during the 31 days centered around October 28, with an average total accumulation of 7.8 inches.

The least rain falls around August 7, with an average total accumulation of 0.7 inches.

The length of the day in Santo António does not vary substantially over the course of the year, staying within 13 minutes of 12 hours throughout. In 2017, the shortest day is December 21, with 12 hours, 2 minutes of daylight; the longest day is June 21, with 12 hours, 13 minutes of daylight.

The earliest sunrise is at 5:12 AM on October 31, and the latest sunrise is 31 minutes later at 5:42 AM on February 9. The earliest sunset is at 5:15 PM on November 5, and the latest sunset is 31 minutes later at 5:46 PM on February 13.

Daylight saving time (DST) is not observed in Santo António 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 Santo António, 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, remaining a virtually constant 100% 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 Santo António experiences mild seasonal variation over the course of the year.

The windier part of the year lasts for 4.9 months, from May 23 to October 20, with average wind speeds of more than 5.3 miles per hour. The windiest day of the year is July 23, with an average hourly wind speed of 6.2 miles per hour.

The calmer time of year lasts for 7.1 months, from October 20 to May 23. The calmest day of the year is January 1, with an average hourly wind speed of 4.4 miles per hour.

The predominant average hourly wind direction in Santo António varies throughout the year.

The wind is most often from the south for 6.6 months, from February 25 to September 13 and for 1.2 months, from October 17 to November 23, with a peak percentage of 82% on June 15. The wind is most often from the west for 1.1 months, from September 13 to October 17 and for 3.1 months, from November 23 to February 25, with a peak percentage of 54% on October 5.

Santo António 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 February 1 to May 19, with an average temperature above 83°F. The day of the year with the warmest water is March 25, with an average temperature of 85°F.

The time of year with cooler water lasts for 2.7 months, from July 9 to October 1, with an average temperature below 80°F. The day of the year with the coolest water is August 12, with an average temperature of 78°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 1.9 months, from August 6 to October 2, with an average daily incident shortwave energy per square meter above 4.4 kWh. The brightest day of the year is August 29, with an average of 4.6 kWh.

The darker period of the year lasts for 2.1 months, from March 16 to May 20, with an average daily incident shortwave energy per square meter below 3.7 kWh. The darkest day of the year is April 28, with an average of 3.5 kWh.

For the purposes of this report, the geographical coordinates of Santo António are 1.637 deg latitude, 7.418 deg longitude, and 400 ft elevation.

The topography within 2 miles of Santo António contains very significant variations in elevation, with a maximum elevation change of 1,037 feet and an average elevation above sea level of 405 feet. Within 10 miles contains very significant variations in elevation (3,077 feet). Within 50 miles also contains large variations in elevation (3,077 feet).

The area within 2 miles of Santo António is covered by cropland (54%) and trees (29%), within 10 miles by water (85%), and within 50 miles by water (99%).

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

Santo António 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 Santo António, 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.