Last updated: August 23, 2025
In September, the average temperature in Rantasalmi, Finland is a cool 10°C (51°F), with minimums dipping to -1°C (30°F) and maximums reaching a pleasant 22°C (73°F). Expect 77 mm (3.0 in) of precipitation over about 14 days, coupled with an average humidity of a humid 90%. Prepare for a mix of cool temps and wet days!
In September in Rantasalmi, the average temperature is 10°C (51°F). The maximum can reach 22°C (73°F), and the minimum can be as low as -1°C (30°F). This makes Rantasalmi a great destination for travelers looking to experience a mix of mild days and cooler evenings.
In Rantasalmi in September, the precipitation amount is 77 mm (3.0 in) over the course of 14 days.
In Rantasalmi 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.
In Rantasalmi 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 Rantasalmi, you can check the information here.
UV Risk Categories
Weather in Rantasalmi varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Rantasalmi, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | -6°C (22°F) | 49 mm (1.9 inches) | 98% | low |
| February Weather | -6°C (21°F) | 44 mm (1.7 inches) | 96% | low |
| March Weather | -3°C (27°F) | 46 mm (1.8 inches) | 93% | moderate |
| April Weather | 2°C (36°F) | 46 mm (1.8 inches) | 88% | moderate |
| May Weather | 10°C (49°F) | 55 mm (2.2 inches) | 77% | moderate |
| June Weather | 16°C (61°F) | 67 mm (2.6 inches) | 75% | high |
| July Weather | 17°C (63°F) | 77 mm (3.0 inches) | 82% | high |
| August Weather | 15°C (60°F) | 81 mm (3.2 inches) | 84% | moderate |
| September Weather | 10°C (51°F) | 77 mm (3.0 inches) | 90% | moderate |
| October Weather | 5°C (42°F) | 76 mm (3.0 inches) | 93% | low |
| November Weather | 1°C (34°F) | 57 mm (2.2 inches) | 93% | low |
| December Weather | -4°C (26°F) | 70 mm (2.8 inches) | 95% | low |