September Weather in Saint Johns, United States

Last updated: June 24, 2025

In Saint Johns, United States, the average temperature in September hovers around 21°C (69°F), providing a pleasant backdrop for outdoor activities. Expect minimum temperatures to dip to 3°C (38°F) while daytime highs can reach up to 34°C (94°F). With a total precipitation of 19 mm (0.8 in) spread over 3 days, you'll want to keep an eye on the weather. The average humidity is a comfortable 62%, making it an inviting time to explore.

September Temperature in Saint Johns

In September in Saint Johns, the average temperature is 21°C (69°F). Maximum temperatures can reach up to 34°C (94°F), while the minimum can dip as low as 3°C (38°F). Be prepared for a diverse range of weather conditions, making it essential to pack accordingly for your travels.

September Weather in Saint Johns: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Saint Johns, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Saint Johns, September typically has an average temperature of 21°C (69°F), with highs reaching up to 34°C (94°F) and lows dropping to around 3°C (38°F).

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

September Precipitation in Saint Johns

In Saint Johns in September, the precipitation amount averaged 19 mm (0.8 in) over a span of 3 days.

September Precipitation Trends in Saint Johns

The chart displays monthly precipitation patterns in Saint Johns, 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 Saint Johns, September typically receives around 19 mm (0.8 inches) of precipitation spread over approximately 3 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 Saint Johns

In Saint Johns in September, humidity is 62%. With an average temperature of 21°C (69°F), this humidity feels like a warm embrace, creating a muggy atmosphere that may leave travelers feeling sticky and fatigued, but it also adds a lushness to the surroundings that's invigorating for outdoor explorations.

September Average Humidity in Saint Johns

This chart illustrates the average monthly humidity levels in Saint Johns, 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 Saint Johns is approximately 62%, 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 Saint Johns

In Saint Johns 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 Saint Johns.

Maximum UV Index Levels in Saint Johns for September

The chart shows the monthly maximum UV Index (UVI) for Saint Johns 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 Saint Johns typically reaches 11, which falls under the extreme exposure category.

Data source: Saint Johns 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 Saint Johns Compares to Other Months

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

This table compares monthly weather conditions in Saint Johns, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	2°C (36°F)	25 mm (1.0 inches)	81%	moderate
February Weather	4°C (40°F)	29 mm (1.1 inches)	83%	high
March Weather	9°C (48°F)	21 mm (0.8 inches)	71%	very high
April Weather	14°C (57°F)	13 mm (0.5 inches)	61%	extreme
May Weather	18°C (64°F)	9 mm (0.4 inches)	48%	extreme
June Weather	24°C (76°F)	6 mm (0.3 inches)	36%	extreme
July Weather	25°C (77°F)	32 mm (1.3 inches)	37%	extreme
August Weather	24°C (76°F)	19 mm (0.8 inches)	46%	extreme
September Weather	21°C (69°F)	19 mm (0.8 inches)	62%	extreme
October Weather	14°C (57°F)	17 mm (0.7 inches)	74%	very high
November Weather	8°C (47°F)	12 mm (0.5 inches)	82%	high
December Weather	3°C (37°F)	19 mm (0.8 inches)	82%	moderate