September Weather in Swansea, United States

Last updated: June 24, 2025

In September, the average temperature in Swansea, United States hovers around 25°C (77°F). Expect a range where temperatures can dip to a minimum of 10°C (51°F) and soar to a maximum of 37°C (99°F). The region experiences 98 mm (3.9 in) of precipitation over 8 days, contributing to an average humidity of 83%. Perfect for those who appreciate a warm, yet refreshing climate!

September Temperature in Swansea

In September in Swansea, the average temperature is 25°C (77°F). Maximum temperatures can reach up to 37°C (99°F), while the minimum can drop as low as 10°C (51°F). Overall, it's a great time to visit Swansea if you enjoy warm weather with a refreshing cooler breeze in the evenings.

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

The chart illustrates September temperature patterns in Swansea, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Swansea, September typically has an average temperature of 25°C (77°F), with highs reaching up to 37°C (99°F) and lows dropping to around 10°C (51°F).

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

September Precipitation in Swansea

In Swansea in September, the total precipitation amount is 98 mm (3.9 in), occurring over 8 days.

September Precipitation Trends in Swansea

The chart displays monthly precipitation patterns in Swansea, 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 Swansea, September typically receives around 98 mm (3.9 inches) of precipitation spread over approximately 8 days.

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

Choose your preferred precipitation unit

Millimeters (mm) Inches (in)

September Humidity in Swansea

In Swansea in September humidity is 83%. With an average temperature of 25°C (77°F), this humidity feels like a warm, enveloping blanket, making it essential for travelers to stay hydrated and seek shade to enjoy their adventures comfortably.

September Average Humidity in Swansea

This chart illustrates the average monthly humidity levels in Swansea, 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 Swansea is approximately 83%, 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 Swansea

In Swansea in September, the maximum UV index is 9, which corresponds to a very high Exposure Category. The time to burn is just 15 minutes, so it's essential to take precautions. For detailed information, you can check the Hourly UV Index in Swansea.

Maximum UV Index Levels in Swansea for September

The chart shows the monthly maximum UV Index (UVI) for Swansea 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 Swansea typically reaches 9, which falls under the very high exposure category.

Data source: Swansea 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 Swansea Compares to Other Months

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

This table compares monthly weather conditions in Swansea, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	9°C (49°F)	83 mm (3.3 inches)	86%	moderate
February Weather	12°C (54°F)	100 mm (3.9 inches)	81%	high
March Weather	15°C (58°F)	76 mm (3.0 inches)	81%	very high
April Weather	19°C (66°F)	112 mm (4.4 inches)	79%	very high
May Weather	23°C (74°F)	105 mm (4.2 inches)	75%	extreme
June Weather	26°C (79°F)	121 mm (4.8 inches)	75%	extreme
July Weather	27°C (82°F)	154 mm (6.1 inches)	80%	extreme
August Weather	27°C (81°F)	141 mm (5.6 inches)	81%	extreme
September Weather	25°C (77°F)	98 mm (3.9 inches)	83%	very high
October Weather	20°C (69°F)	71 mm (2.8 inches)	78%	very high
November Weather	13°C (55°F)	61 mm (2.4 inches)	85%	high
December Weather	10°C (51°F)	129 mm (5.1 inches)	87%	moderate