September Weather in Fortuna, United States

Last updated: June 24, 2025

In September, the average temperature in Fortuna, United States hovers around 16°C (61°F). While you can expect a minimum of 8°C (47°F), the mercury can rise as high as 32°C (90°F). During this time, the area receives about 20 mm (0.8 in) of precipitation over 3 days, and average humidity rests at a comfortable 62%.

September Temperature in Fortuna

In September in Fortuna, the average temperature is 16°C (61°F). Maximum can reach 32°C (90°F) and minimum can be as low as 8°C (47°F). Be prepared for a range of temperatures, making it ideal for both outdoor activities and comfortable evenings.

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

The chart illustrates September temperature patterns in Fortuna, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Fortuna, September typically has an average temperature of 16°C (61°F), with highs reaching up to 32°C (90°F) and lows dropping to around 8°C (47°F).

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

September Precipitation in Fortuna

In Fortuna in September, the precipitation amount is 20 mm (0.8 in) accumulated over a period of 3 days.

September Precipitation Trends in Fortuna

The chart displays monthly precipitation patterns in Fortuna, 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 Fortuna, September typically receives around 20 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 Fortuna

In Fortuna in September, humidity is 62%. With an average temperature of 16°C (61°F), this humidity feels like a gentle blanket, making traveling comfortable yet occasionally sticky, prompting the need for light, breathable clothing to fully enjoy the sights.

September Average Humidity in Fortuna

This chart illustrates the average monthly humidity levels in Fortuna, 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 Fortuna 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 Fortuna

In Fortuna in September, the maximum UV index is 8, which corresponds to a very high Exposure Category. This means that the time to burn is only 15 minutes. For more detailed information, you can refer to the Hourly UV Index in Fortuna.

Maximum UV Index Levels in Fortuna for September

The chart shows the monthly maximum UV Index (UVI) for Fortuna 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 Fortuna typically reaches 8, which falls under the very high exposure category.

Data source: Fortuna 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 Fortuna Compares to Other Months

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

This table compares monthly weather conditions in Fortuna, 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 (48°F)	205 mm (8.1 inches)	86%	moderate
February Weather	8°C (47°F)	188 mm (7.4 inches)	85%	moderate
March Weather	9°C (48°F)	164 mm (6.5 inches)	85%	high
April Weather	10°C (51°F)	93 mm (3.7 inches)	82%	very high
May Weather	12°C (53°F)	61 mm (2.4 inches)	81%	very high
June Weather	14°C (57°F)	17 mm (0.7 inches)	79%	extreme
July Weather	15°C (59°F)	2 mm (0.1 inches)	70%	very high
August Weather	16°C (61°F)	2 mm (0.1 inches)	60%	very high
September Weather	16°C (61°F)	20 mm (0.8 inches)	62%	very high
October Weather	13°C (56°F)	49 mm (1.9 inches)	72%	high
November Weather	11°C (51°F)	112 mm (4.4 inches)	87%	moderate
December Weather	9°C (48°F)	150 mm (5.9 inches)	86%	low