The highest day temperature in September 2025 was 75°F. The lowest night temperature was 39°F. The average values for day and night temperatures during September were 63.4°F и 51.0°F respectivly.

The average sea surface temperature in September 2025 for Jonkoping was 60.7°F. The maximum and minimum values were 55.2°F and 64.0°F respectively.

You can expect various weather conditions during September. Be ready for sunny, cloudy or even gloomy days.

Precipitation total in September for Jonkoping is 1.3 in.

The average wind speed in September is 8.4 mph. This value is relatively stable throughout the year.

We are using day length and cloud cover information for each day of the month to calculate averages for this chart. Average sunny hours for Jonkoping in September is 6.4 hours.