September Weather in Koster, South Africa

Last updated: August 31, 2025

In September, the average temperature in Koster, South Africa is a pleasant 20°C (68°F). However, be prepared for a range as the temperature can drop to a minimum of 3°C (38°F) or rise to a sizzling 35°C (95°F). Expect light precipitation, averaging 5 mm (0.2 in) over just 1 day, and enjoy a comfortable average humidity level of 49%.

September Temperature in Koster

In September in Koster, the average temperature is 20°C (68°F). Maximums can reach up to 35°C (95°F), while minimums can drop as low as 3°C (38°F). Be sure to pack a variety of clothing to accommodate the temperature fluctuations during your travels.

September Weather in Koster: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Koster, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Koster, September typically has an average temperature of 20°C (68°F), with highs reaching up to 35°C (95°F) and lows dropping to around 3°C (38°F).

Data source: Temperature data for Koster generated using information from the Copernicus Climate Change Service.

September Precipitation in Koster

In Koster in September, the precipitation amount is 5 mm (0.2 in) over a duration of 1 day.

September Precipitation Trends in Koster

The chart displays monthly precipitation patterns in Koster, with values for each month alongside September’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how September’s conditions compare to those of other months. In Koster, September typically receives around 5 mm (0.2 inches) of precipitation spread over approximately 1 days.

Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.

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Millimeters (mm) Inches (in)

September Humidity in Koster

In Koster in September, humidity is 49%. With an average temperature of 20°C (68°F), this humidity feels like a comfortable embrace, creating a pleasant backdrop for exploring the sights without feeling overly sticky or weighed down.

September Average Humidity in Koster

This chart illustrates the average monthly humidity levels in Koster, with September’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In September, average humidity in Koster is approximately 49%, offering insight into how humid the weather typically is during this month.

Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Koster

In Koster in September, the maximum UV index reaches 11, which corresponds to an extreme Exposure Category. With a time to burn of just 10 minutes, it's essential to take precautions. For more details, you can check the Hourly UV Index in Koster.

Maximum UV Index Levels in Koster for September

The chart shows the monthly maximum UV Index (UVI) for Koster in September, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In September, the maximum UV index in Koster typically reaches 11, which falls under the extreme exposure category.

Data source: Koster September UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

Extreme (11+): Avoid the sun, stay in shade.
Very High (8-10): Limit sun exposure.
High (6-7): Use SPF 30+ and protective clothing.
Moderate (3-5): Midday shade recommended.
Low (0-2): No protection needed.

How September Weather in Koster Compares to Other Months

Weather in Koster varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Koster, focusing on differences in temperature, rainfall, humidity, and UV levels.

This table compares monthly weather conditions in Koster, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	23°C (74°F)	106 mm (4.2 inches)	66%	extreme
February Weather	22°C (72°F)	128 mm (5.0 inches)	66%	extreme
March Weather	21°C (70°F)	53 mm (2.1 inches)	67%	extreme
April Weather	18°C (65°F)	43 mm (1.7 inches)	61%	extreme
May Weather	15°C (59°F)	9 mm (0.4 inches)	56%	high
June Weather	12°C (55°F)	5 mm (0.2 inches)	56%	high
July Weather	12°C (54°F)	2 mm (0.1 inches)	55%	high
August Weather	16°C (61°F)	1 mm (0.1 inches)	45%	very high
September Weather	20°C (68°F)	5 mm (0.2 inches)	49%	extreme
October Weather	21°C (71°F)	47 mm (1.9 inches)	47%	extreme
November Weather	23°C (73°F)	67 mm (2.7 inches)	53%	extreme
December Weather	23°C (73°F)	120 mm (4.7 inches)	64%	extreme