Average Weather in Zanzibar Tanzania
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.
Based on the beach/pool score, the best time of year to visit Zanzibar for hot-weather activities is from early June to early October.
The temperature in Zanzibar varies so little throughout the year that it is not entirely meaningful to discuss hot and cold seasons.
Average High and Low Temperature
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
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
Santiago de Cuba, Cuba (7,995 miles away); Brenas, Puerto Rico (7,377 miles); and Itaparica, Brazil (5,316 miles) are the far-away foreign places with temperatures most similar to Zanzibar (view comparison).
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 10 and lasts for 6.1 months, ending around November 15. On August 31, 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 15 and lasts for 5.9 months, ending around May 10. On March 14, 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.
Cloud Cover Categories
0% clear 20% mostly clear 40% partly cloudy 60% mostly cloudy 80% overcast 100%
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 6.2 months, from November 16 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 19.
The drier season lasts 5.8 months, from May 21 to November 16. The smallest chance of a wet day is 4% on July 18.
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 19.
Daily Chance of Precipitation
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 9.5 months, from September 23 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 21, 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 23. The least rain falls around August 28, with an average total accumulation of 0.3 inches.
Average Monthly Rainfall
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 2020, 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.
Hours of Daylight and Twilight
The earliest sunrise is at 5:55 AM on November 13, and the latest sunrise is 39 minutes later at 6:35 AM on July 17. The earliest sunset is at 6:14 PM on May 23, and the latest sunset is 34 minutes later at 6:47 PM on February 1.
Daylight saving time (DST) is not observed in Zanzibar during 2020.
Sunrise & Sunset with 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.
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.
Humidity Comfort Levels
dry 55°F comfortable 60°F humid 65°F muggy 70°F oppressive 75°F miserable
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 9, with average wind speeds of more than 11.2 miles per hour. The windiest day of the year is July 3, with an average hourly wind speed of 14.3 miles per hour.
The calmer time of year lasts for 6.4 months, from October 9 to April 23. The calmest day of the year is March 24, with an average hourly wind speed of 8.0 miles per hour.
Average Wind Speed
The predominant average hourly wind direction in Zanzibar varies throughout the year.
The wind is most often from the east for 1.5 months, from February 20 to April 6 and for 3.7 months, from August 28 to December 20, with a peak percentage of 90% on November 5. The wind is most often from the south for 4.7 months, from April 6 to August 28, with a peak percentage of 95% on June 16. The wind is most often from the north for 2.0 months, from December 20 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 2.3 months, from February 16 to April 26, with an average temperature above 83°F. The day of the year with the warmest water is March 24, with an average temperature of 85°F.
The time of year with cooler water lasts for 3.0 months, from July 2 to October 4, with an average temperature below 79°F. The day of the year with the coolest water is August 13, with an average temperature of 78°F.
Average Water Temperature
Best Time of Year to Visit
To characterize how pleasant the weather is in Zanzibar 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 Zanzibar for general outdoor tourist activities is from late June to mid September, with a peak score in the second week of August.
The beach/pool score favors clear, rainless days with perceived temperatures between 75°F and 90°F. Based on this score, the best time of year to visit Zanzibar for hot-weather activities is from early June to early October, with a peak score in the last week of August.
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 Zanzibar 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
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
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
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 11, with an average daily incident shortwave energy per square meter above 6.9 kWh. The brightest day of the year is October 9, with an average of 7.3 kWh.
The darker period of the year lasts for 2.2 months, from March 10 to May 18, with an average daily incident shortwave energy per square meter below 5.7 kWh. The darkest day of the year is April 5, with an average of 5.3 kWh.
Average Daily Incident Shortwave Solar Energy
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.
All data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Algorithms 2nd Edition , 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.
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.