- The average temperature in Basel is mild at 15 °C (59 °F).
- Afternoons can be really warm with average high temperatures reaching 22 °C (71.6 °F).
- Overnight temperatures are generally quite mild with an average low of 10 °C (50 °F).
- In September the average diurnal temperature range/ variation is 12 °C (21.6 °F).
- The weather in September is somewhat dry with rain occasionally. Just 79mm (3.1in) of liquid precipitates across on average 12 days.
- In September the skies in Basel are slightly fair with an average of a mediocre 5:09 of resplendent sunlight per day.
- The shortest day is 11:39 long and the longest day is 13:21 long with an average length of 12:30.
- There are approximately 7:09 per day when bright sunshine is absent due to cloud, haze or the sun being too low on the horizon to register.
- It is sunny approximately 41.9% of daylight hours and cloudy 58.1% of daylight hours.
Weather Trend Graph for September in Basel, Switzerland
Basel Weather in September Discussion
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