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  5. September

Average Weather in September in Windhoek Namibia

Daily high temperatures increase by 5°F, from 80°F to 84°F, rarely falling below 73°F or exceeding 90°F.

Daily low temperatures increase by 5°F, from 54°F to 59°F, rarely falling below 46°F or exceeding 67°F.

For reference, on December 21, the hottest day of the year, temperatures in Windhoek typically range from 65°F to 89°F, while on July 7, the coldest day of the year, they range from 46°F to 70°F.

Average High and Low Temperature in September

The daily average high (red line) and low (blue line) temperature, with 25th to 75th and 10th to 90th percentile bands. The thin dotted lines are the corresponding average perceived temperatures.

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

Average Hourly Temperature in September in Windhoek1815222911223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303012 AM4 AM8 AM12 PM4 PM8 PM12 AMAugOctcoldcoolcoolcomfortablecomfortablewarmhot
The average hourly temperature, color coded into bands: 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. The shaded overlays indicate night and civil twilight.

Cerritos, Mexico (8,480 miles away); La Mendieta, Argentina (5,124 miles); and São Carlos, Brazil (4,123 miles) are the far-away foreign places with temperatures most similar to Windhoek (view comparison).

Clouds

The month of September in Windhoek experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 11% throughout the month.

The clearest day of the month is September 1, with clear, mostly clear, or partly cloudy conditions 91% of the time.

For reference, on January 29, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 49%, while on June 13, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 93%.

Cloud Cover Categories in September

Cloud Cover Categories in September in Windhoek181522291122334455667788991010111112121313141415151616171718181919202021212222232324242525262627272828292930300%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%AugOctSep 191%Sep 191%Sep 3087%Sep 3087%Sep 1189%Sep 1189%Sep 2188%Sep 2188%clearmostly clearovercastpartly cloudymostly cloudy
The percentage of time spent in each cloud cover band, categorized by the percentage of the sky covered by clouds: clear < 20% < mostly clear < 40% < partly cloudy < 60% < mostly cloudy < 80% < overcast.

Precipitation

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Windhoek, the chance of a wet day over the course of September is gradually increasing, starting the month at 1% and ending it at 4%.

For reference, the year's highest daily chance of a wet day is 38% on January 30, and its lowest chance is 0% on June 30.

Probability of Precipitation in September

The percentage of days in which various types of precipitation are observed, excluding trace quantities: rain alone, snow alone, and mixed (both rain and snow fell in the same day).

Rainfall

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 Windhoek is essentially constant, remaining about 0.1 inches throughout, and rarely exceeding 0.8 inches or falling below -0.0 inches.

Average Monthly Rainfall in September

The average rainfall (solid line) accumulated over the course of a sliding 31-day period centered on the day in question, with 25th to 75th and 10th to 90th percentile bands. The thin dotted line is the corresponding average liquid-equivalent snowfall.

Sun

Over the course of September in Windhoek, the length of the day is increasing. From the start to the end of the month, the length of the day increases by 37 minutes, implying an average daily increase of 1 minute, 17 seconds, and weekly increase of 8 minutes, 56 seconds.

The shortest day of the month is September 1, with 11 hours, 40 minutes of daylight and the longest day is September 30, with 12 hours, 17 minutes of daylight.

Hours of Daylight and Twilight in September

Hours of Daylight and Twilight in September in Windhoek181522291122334455667788991010111112121313141415151616171718181919202021212222232324242525262627272828292930300 hr24 hr4 hr20 hr8 hr16 hr12 hr12 hr16 hr8 hr20 hr4 hr24 hr0 hrAugOctSep 2312 hr, 6 minSep 2312 hr, 6 mindaydaydaydaynightSep 111 hr, 40 minSep 111 hr, 40 min
The number of hours during which the Sun is visible (black line). From bottom (most yellow) to top (most gray), the color bands indicate: full daylight, twilight (civil, nautical, and astronomical), and full night.

The earliest sunrise of the month in Windhoek is 6:02 AM on September 1 and the latest sunrise is 59 minutes later at 7:01 AM on September 2.

The earliest sunset is 5:41 PM on September 1 and the latest sunset is 1 hour, 8 minutes later at 6:50 PM on September 30.

Daylight saving time (DST) starts at 3:00 AM on September 2, 2018, shifting sunrise and sunset to be an hour later.

For reference, on December 21, the longest day of the year, the Sun rises at 6:04 AM and sets 13 hours, 31 minutes later, at 7:35 PM, while on June 21, the shortest day of the year, it rises at 6:30 AM and sets 10 hours, 45 minutes later, at 5:15 PM.

Sunrise & Sunset with Twilight and Daylight Saving Time in September

The solar day over the course of September. From bottom to top, the black lines are the previous solar midnight, sunrise, solar noon, sunset, and the next solar midnight. The day, twilights (civil, nautical, and astronomical), and night are indicated by the color bands from yellow to gray. The transitions to and from daylight saving time are indicated by the 'DST' labels.

Humidity

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 Windhoek is essentially constant during September, remaining around 0% throughout.

For reference, on January 4, the muggiest day of the year, there are muggy conditions 0% of the time, while on April 6, the least muggy day of the year, there are muggy conditions 0% of the time.

Humidity Comfort Levels in September

The percentage of time spent at various humidity comfort levels, categorized by dew point: dry < 55°F < comfortable < 60°F < humid < 65°F < muggy < 70°F < oppressive < 75°F < miserable.

Wind

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 Windhoek is essentially constant during September, remaining within 0.1 miles per hour of 9.6 miles per hour throughout.

For reference, on July 16, the windiest day of the year, the daily average wind speed is 9.8 miles per hour, while on March 8, the calmest day of the year, the daily average wind speed is 6.8 miles per hour.

Average Wind Speed in September

The average of mean hourly wind speeds (dark gray line), with 25th to 75th and 10th to 90th percentile bands.
The wind direction in Windhoek during September is predominantly out of the north from September 1 to September 7, the west from September 7 to September 22 and from September 22 to September 28, and the east from September 28 to September 30.

Wind Direction in September

Wind Direction in September in WindhoekNWWEEW181522291122334455667788991010111112121313141415151616171718181919202021212222232324242525262627272828292930300%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%AugOctwestsoutheastnorth
The percentage of hours in which the mean wind direction is from each of the four cardinal wind directions (north, east, south, and west), excluding hours in which the mean wind speed is less than 1 mph. The lightly tinted areas at the boundaries are the percentage of hours spent in the implied intermediate directions (northeast, southeast, southwest, and northwest).

Growing Season

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 Windhoek 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 in September

Time Spent in Various Temperature Bands and the Growing Season in September in Windhoek181522291122334455667788991010111112121313141415151616171718181919202021212222232324242525262627272828292930300%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%AugOct100%Sep 16100%Sep 16coldcoolcomfortablewarmhotvery cold
The percentage of time spent in various temperature bands: 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. The black line is the percentage chance that a given day is within the growing season.

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.

The average accumulated growing degree days in Windhoek are rapidly increasing during September, increasing by 563°F, from 700°F to 1,264°F, over the course of the month.

Growing Degree Days in September

The average growing degree days accumulated over the course of September, with 25th to 75th and 10th to 90th percentile bands.

Solar Energy

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 Windhoek is gradually increasing during September, rising by 0.9 kWh, from 6.5 kWh to 7.4 kWh, over the course of the month.

Average Daily Incident Shortwave Solar Energy in September

The average daily shortwave solar energy reaching the ground per square meter (orange line), with 25th to 75th and 10th to 90th percentile bands.

Topography

For the purposes of this report, the geographical coordinates of Windhoek are -22.559 deg latitude, 17.083 deg longitude, and 5,482 ft elevation.

The topography within 2 miles of Windhoek contains significant variations in elevation, with a maximum elevation change of 600 feet and an average elevation above sea level of 5,486 feet. Within 10 miles contains significant variations in elevation (3,281 feet). Within 50 miles also contains extreme variations in elevation (4,928 feet).

The area within 2 miles of Windhoek is covered by artificial surfaces (94%), within 10 miles by grassland (83%) and artificial surfaces (16%), and within 50 miles by grassland (98%).

Data Sources

This report illustrates the typical weather in Windhoek 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 is only a single weather station, Windhoek, Town MET, in our network suitable to be used as a proxy for the historical temperature and dew point records of Windhoek.

At a distance of 2 kilometer from Windhoek, 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 Windhoek 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.

Disclaimer

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.