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Average Weather in September in Banjul Gambia

In Banjul, the month of September is characterized by gradually rising daily high temperatures, with daily highs increasing by 2°F, from 88°F to 90°F over the course of the month, and rarely exceeding 92°F or dropping below 84°F.

Daily low temperatures are around 75°F, rarely falling below 72°F or exceeding 78°F.

For reference, on March 8, the hottest day of the year, temperatures in Banjul typically range from 68°F to 95°F, while on January 11, the coldest day of the year, they range from 64°F to 90°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 Banjul12 AM4 AM8 AM12 PM4 PM8 PM12 AM18152229112233445566778899101011111212131314141515161617171818191920202121222223232424252526262727282829293030AugOctcomfortablewarmhot
The average hourly temperature, color coded into bands: frigid < 15°F < freezing < 32°F < chilly < 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.

Clouds

The month of September in Banjul experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 80% throughout the month. The highest chance of overcast or mostly cloudy conditions is 81% on September 10.

The clearest day of the month is September 30, with clear, mostly clear, or partly cloudy conditions 20% of the time.

For reference, on September 10, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 81%, while on May 3, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 65%.

Cloud Cover in September

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 Banjul, the chance of a wet day over the course of September is very rapidly decreasing, starting the month at 77% and ending it at 44%.

For reference, the year's highest daily chance of a wet day is 79% on August 27, and its lowest chance is 0% on March 28.

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 Banjul is very rapidly decreasing, starting the month at 8.8 inches, when it rarely exceeds 12.8 inches or falls below 5.1 inches, and ending the month at 3.9 inches, when it rarely exceeds 6.5 inches or falls below 2.0 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 Banjul, the length of the day is gradually decreasing. From the start to the end of the month, the length of the day decreases by 21 minutes, implying an average daily decrease of 44 seconds, and weekly decrease of 5 minutes, 10 seconds.

The shortest day of the month is September 30, with 12 hours, 1 minute of daylight and the longest day is September 1, with 12 hours, 22 minutes of daylight.

Hours of Daylight and Twilight in September

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 Banjul is 6:54 AM on September 1 and the latest sunrise is 41 seconds later at 6:55 AM on September 30.

The latest sunset is 7:17 PM on September 1 and the earliest sunset is 21 minutes earlier at 6:56 PM on September 30.

Daylight saving time is not observed in Banjul during 2017.

For reference, on June 21, the longest day of the year, the Sun rises at 6:40 AM and sets 12 hours, 55 minutes later, at 7:35 PM, while on December 21, the shortest day of the year, it rises at 7:24 AM and sets 11 hours, 20 minutes later, at 6:44 PM.

Sunrise & Sunset with Twilight 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.

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 Banjul is essentially constant during September, remaining around 100% throughout.

For reference, on August 7, the muggiest day of the year, there are muggy conditions 100% of the time, while on January 18, the least muggy day of the year, there are muggy conditions 1% of the time.

Humidity Comfort Levels in September

Humidity Comfort Levels in September in Banjul0%10%20%30%40%50%60%70%80%90%100%18152229112233445566778899101011111212131314141515161617171818191920202121222223232424252526262727282829293030AugOctSep 1100%Sep 1100%Sep 30100%Sep 30100%Sep 11100%Sep 11100%Sep 21100%Sep 21100%miserablemiserableoppressiveoppressivemuggymuggycomfortablecomfortable
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 Banjul is gradually decreasing during September, decreasing from 3.4 miles per hour to 2.8 miles per hour over the course of the month.

For reference, on April 8, the windiest day of the year, the daily average wind speed is 4.8 miles per hour, while on October 9, the calmest day of the year, the daily average wind speed is 2.8 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 hourly average wind direction in Banjul throughout September is predominantly from the west, with a peak proportion of 58% on September 1.

Wind Direction in September

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).

Water Temperature

Banjul 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 Banjul is essentially constant during September, remaining around 83°F throughout.

Average Water Temperature in September

The daily average water temperature (purple line), 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 Banjul is essentially constant during September, remaining around 4.3 kWh throughout.

The lowest average daily incident shortwave solar energy during September is 4.3 kWh on September 29.

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 Banjul are 13.453 deg latitude, -16.578 deg longitude, and 0 ft elevation.

The topography within 2 miles of Banjul is essentially flat, with a maximum elevation change of 66 feet and an average elevation above sea level of 3 feet. Within 10 miles is essentially flat (157 feet). Within 50 miles also contains only modest variations in elevation (243 feet).

The area within 2 miles of Banjul is covered by water (86%), within 10 miles by water (58%) and cropland (17%), and within 50 miles by water (45%) and cropland (22%).

Data Sources

This report illustrates the typical weather in Banjul 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 3 weather stations near enough to contribute to our estimation of the temperature and dew point in Banjul.

For each station, the records are corrected for the elevation difference between that station and Banjul 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 Banjul is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Banjul and a given station.

The stations contributing to this reconstruction are: Banjul International Airport (92%, 15 kilometers, southwest); Kaolack Airport (6%, 96 kilometers, northeast); and Léopold Sédar Senghor International Airport (2.4%, 174 kilometers, northwest).

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.