Average Weather in September in Cape Town South Africa
In Cape Town, the month of September is characterized by gradually rising daily high temperatures, with daily highs increasing by 2°F, from 64°F to 66°F over the course of the month, and rarely exceeding 75°F or dropping below 58°F.
Daily low temperatures increase by 2°F, from 50°F to 52°F, rarely falling below 44°F or exceeding 57°F.
For reference, on January 27, the hottest day of the year, temperatures in Cape Town typically range from 63°F to 76°F, while on July 11, the coldest day of the year, they range from 48°F to 62°F.
Average High and Low Temperature in September
The figure below shows you a compact characterization of the hourly average temperatures for the quarter of the year centered on September. The horizontal axis is the day, 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 September
The month of September in Cape Town experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 39% throughout the month. The highest chance of overcast or mostly cloudy conditions is 40% on September 11.
The clearest day of the month is September 30, with clear, mostly clear, or partly cloudy conditions 63% of the time.
For reference, on May 19, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 44%, while on February 10, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 89%.
Cloud Cover in September
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Cape Town, the chance of a wet day over the course of September is decreasing, starting the month at 20% and ending it at 16%.
For reference, the year's highest daily chance of a wet day is 27% on June 15, and its lowest chance is 4% on February 13.
Probability of Precipitation in September
To show variation within the month and not just the monthly total, we show the rainfall accumulated over a sliding 31-day period centered around each day.
The average sliding 31-day rainfall during September in Cape Town is decreasing, starting the month at 1.8 inches, when it rarely exceeds 3.4 inches or falls below 0.4 inches, and ending the month at 1.1 inches, when it rarely exceeds 2.2 inches or falls below 0.2 inches.
Average Monthly Rainfall in September
Over the course of September in Cape Town, the length of the day is increasing. From the start to the end of the month, the length of the day increases by 60 minutes, implying an average daily increase of 2 minutes, 4 seconds, and weekly increase of 14 minutes, 29 seconds.
The shortest day of the month is September 1, with 11 hours, 24 minutes of daylight and the longest day is September 30, with 12 hours, 24 minutes of daylight.
Hours of Daylight and Twilight in September
The latest sunrise of the month in Cape Town is 7:04 AM on September 1 and the earliest sunrise is 40 minutes earlier at 6:24 AM on September 30.
The earliest sunset is 6:28 PM on September 1 and the latest sunset is 20 minutes later at 6:48 PM on September 30.
Daylight saving time is not observed in Cape Town during 2017.
For reference, on December 21, the longest day of the year, the Sun rises at 5:31 AM and sets 14 hours, 25 minutes later, at 7:57 PM, while on June 21, the shortest day of the year, it rises at 7:51 AM and sets 9 hours, 54 minutes later, at 5:44 PM.
Sunrise & Sunset with Twilight in September
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 chance that a given day will be muggy in Cape Town is essentially constant during September, remaining around 0% throughout.
For reference, on February 11, the muggiest day of the year, there are muggy conditions 9% of the time, while on May 25, the least muggy day of the year, there are muggy conditions 0% of the time.
Humidity Comfort Levels in September
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 Cape Town is essentially constant during September, remaining within 0.1 miles per hour of 6.4 miles per hour throughout.
For reference, on January 22, the windiest day of the year, the daily average wind speed is 7.5 miles per hour, while on May 3, the calmest day of the year, the daily average wind speed is 5.7 miles per hour.
Average Wind Speed in September
Wind Direction in September
Cape Town 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 surface water temperature in Cape Town is essentially constant during September, remaining around 59°F throughout.
Average Water Temperature in September
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 in Cape Town is increasing during September, rising by 1.5 kWh, from 4.2 kWh to 5.7 kWh, over the course of the month.
Average Daily Incident Shortwave Solar Energy in September
For the purposes of this report, the geographical coordinates of Cape Town are -33.926 deg latitude, 18.423 deg longitude, and 82 ft elevation.
The topography within 2 miles of Cape Town contains large variations in elevation, with a maximum elevation change of 2,405 feet and an average elevation above sea level of 318 feet. Within 10 miles contains large variations in elevation (3,596 feet). Within 50 miles also contains extreme variations in elevation (6,568 feet).
The area within 2 miles of Cape Town is covered by artificial surfaces (69%) and shrubs (20%), within 10 miles by water (46%) and artificial surfaces (39%), and within 50 miles by water (62%) and cropland (22%).
This report illustrates the typical weather in Cape Town year round, 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 are 2 weather stations near enough to contribute to our estimation of the temperature and dew point in Cape Town.
For each station, the records are corrected for the elevation difference between that station and Cape Town according to the International Standard Atmosphere , and by the relative change present in the MERRA-2 satellite-era reanalysis between the two locations.
The estimated value at Cape Town is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Cape Town and a given station.
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.