Average Weather in Zanzibar Tanzania

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2. Tanzania
3. Zanzibar Urban/West
4. Mjini
5. Zanzibar

In Zanzibar, the wet season is hot and mostly cloudy; the dry season is warm, windy, and mostly clear; and it is oppressive year round. Over the course of the year, the temperature typically varies from 70°F to 91°F and is rarely below 67°F or above 93°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 Zanzibar, the average percentage of the sky covered by clouds experiences extreme seasonal variation over the course of the year.

The clearer part of the year in Zanzibar begins around May 11 and lasts for 6.2 months, ending around November 17. On September 1, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 79% of the time, and overcast or mostly cloudy 21% of the time.

The cloudier part of the year begins around November 17 and lasts for 5.8 months, ending around May 11. On March 15, the cloudiest day of the year, the sky is overcast or mostly cloudy 73% of the time, and clear, mostly clear, or partly cloudy 27% 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 Zanzibar varies very significantly throughout the year.

The wetter season lasts 6.1 months, from November 17 to May 21, with a greater than 34% chance of a given day being a wet day. The chance of a wet day peaks at 64% on April 20.

The drier season lasts 5.9 months, from May 21 to November 17. The smallest chance of a wet day is 4% on July 19.

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 April 20.

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. Zanzibar experiences extreme seasonal variation in monthly rainfall.

The rainy period of the year lasts for 9.4 months, from September 24 to July 5, with a sliding 31-day rainfall of at least 0.5 inches. The most rain falls during the 31 days centered around April 22, with an average total accumulation of 6.8 inches.

The rainless period of the year lasts for 2.6 months, from July 5 to September 24. The least rain falls around August 29, with an average total accumulation of 0.3 inches.

The length of the day in Zanzibar does not vary substantially over the course of the year, staying within 29 minutes of 12 hours throughout. In 2017, the shortest day is June 21, with 11 hours, 46 minutes of daylight; the longest day is December 21, with 12 hours, 29 minutes of daylight.

The earliest sunrise is at 5:55 AM on November 12, and the latest sunrise is 39 minutes later at 6:35 AM on July 18. The earliest sunset is at 6:14 PM on May 23, and the latest sunset is 34 minutes later at 6:47 PM on January 31.

Daylight saving time (DST) is not observed in Zanzibar 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 Zanzibar, 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 4% of 96% 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 Zanzibar experiences significant seasonal variation over the course of the year.

The windier part of the year lasts for 5.6 months, from April 23 to October 11, with average wind speeds of more than 6.0 miles per hour. The windiest day of the year is July 4, with an average hourly wind speed of 7.7 miles per hour.

The calmer time of year lasts for 6.4 months, from October 11 to April 23. The calmest day of the year is March 25, with an average hourly wind speed of 4.3 miles per hour.

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

The wind is most often from the east for 1.6 months, from February 20 to April 7 and for 3.7 months, from August 29 to December 21, with a peak percentage of 90% on November 6. The wind is most often from the south for 4.7 months, from April 7 to August 29, with a peak percentage of 95% on June 17. The wind is most often from the north for 2.0 months, from December 21 to February 20, with a peak percentage of 60% on January 1.

Zanzibar 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 2.4 months, from February 15 to April 28, 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 3.1 months, from July 3 to October 5, with an average temperature below 79°F. The day of the year with the coolest water is August 14, 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 2.2 months, from September 6 to November 12, with an average daily incident shortwave energy per square meter above 6.9 kWh. The brightest day of the year is October 10, with an average of 7.3 kWh.

The darker period of the year lasts for 2.3 months, from March 11 to May 19, with an average daily incident shortwave energy per square meter below 5.7 kWh. The darkest day of the year is April 6, with an average of 5.3 kWh.

For the purposes of this report, the geographical coordinates of Zanzibar are -6.164 deg latitude, 39.198 deg longitude, and 0 ft elevation.

The topography within 2 miles of Zanzibar contains only modest variations in elevation, with a maximum elevation change of 144 feet and an average elevation above sea level of 27 feet. Within 10 miles also contains only modest variations in elevation (440 feet). Within 50 miles contains only modest variations in elevation (1,171 feet).

The area within 2 miles of Zanzibar is covered by artificial surfaces (44%), water (44%), and cropland (11%), within 10 miles by water (56%) and cropland (29%), and within 50 miles by water (63%) and trees (13%).

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

Temperature and Dew Point

There is only a single weather station, Abeid Amani Karume International Airport, in our network suitable to be used as a proxy for the historical temperature and dew point records of Zanzibar.

At a distance of 7 kilometers from Zanzibar, closer than our threshold of 150 kilometers, this station is deemed sufficiently nearby to be relied upon as our primary source for temperature and dew point records.

The station records are corrected for the elevation difference between the station and Zanzibar according to the International Standard Atmosphere , and by the relative change present in the MERRA-2 satellite-era reanalysis between the two locations.

Please note that the station records themselves may additionally have been back-filled using other nearby stations or the MERRA-2 reanalysis.

Other Data

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.

All other weather data, including cloud cover, precipitation, wind speed and direction, and solar flux, come from NASA's MERRA-2 Modern-Era Retrospective Analysis . 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.

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.