September Weather in Ii, Finland

Last updated: August 23, 2025

In September, the average temperature in Ii, Finland hovers around 10°C (51°F), with a minimum of 0°C (33°F) and a refreshing maximum of 21°C (70°F). Expect a significant precipitation of 84 mm (3.3 in) spread across 14 days, contributing to a high average humidity of 90%. Prepare for some wet days ahead!

September Temperature in Ii

In September in Ii, the average temperature is 10°C (51°F). The maximum can reach 21°C (70°F), while the minimum can be as low as 0°C (33°F). It's an ideal time for travelers to enjoy mild weather, making it perfect for outdoor activities and sightseeing.

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

The chart illustrates September temperature patterns in Ii, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Ii, September typically has an average temperature of 10°C (51°F), with highs reaching up to 21°C (70°F) and lows dropping to around 0°C (33°F).

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

September Precipitation in Ii

In Ii in September, the precipitation amount is 84 mm (3.3 in) over the course of 14 days.

September Precipitation Trends in Ii

The chart displays monthly precipitation patterns in Ii, 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 Ii, September typically receives around 84 mm (3.3 inches) of precipitation spread over approximately 14 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 Ii

In Ii in September, humidity is 90%. With an average temperature of 10°C (51°F), this humidity feels like you are wrapped in a damp blanket, making traveling quite uncomfortable and sticky, as the air hangs heavy around you, often leading to fatigue and a longing for cooler, drier conditions.

September Average Humidity in Ii

This chart illustrates the average monthly humidity levels in Ii, 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 Ii is approximately 90%, 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 Ii

In Ii in September, the maximum UV index is 3, which corresponds to a moderate Exposure Category. The time to burn is approximately 30 minutes. For more details on the hourly UV index in Ii, you can check the information here.

Maximum UV Index Levels in Ii for September

The chart shows the monthly maximum UV Index (UVI) for Ii 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 Ii typically reaches 3, which falls under the moderate exposure category.

Data source: Ii 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 Ii Compares to Other Months

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

This table compares monthly weather conditions in Ii, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	-7°C (20°F)	45 mm (1.8 inches)	100%	low
February Weather	-8°C (18°F)	43 mm (1.7 inches)	98%	low
March Weather	-5°C (24°F)	44 mm (1.7 inches)	95%	moderate
April Weather	-1°C (31°F)	39 mm (1.5 inches)	87%	moderate
May Weather	5°C (42°F)	51 mm (2.0 inches)	81%	moderate
June Weather	13°C (56°F)	59 mm (2.3 inches)	77%	high
July Weather	17°C (63°F)	68 mm (2.7 inches)	79%	high
August Weather	15°C (59°F)	92 mm (3.6 inches)	84%	moderate
September Weather	10°C (51°F)	84 mm (3.3 inches)	90%	moderate
October Weather	5°C (41°F)	105 mm (4.1 inches)	95%	low
November Weather	0°C (33°F)	76 mm (3.0 inches)	95%	low
December Weather	-4°C (25°F)	66 mm (2.6 inches)	99%	low