Contents
- Weather in September
- Frequently asked questions
- Average temperature in September
- Average pressure in September
- Average wind speed in September
- Average humidity in September
- Average rainfall in September
- Average rainfall days in September
- Average snowfall in September
- Average snowfall days in September
- Average daylight in September
- Average sunshine in September
- Average sunshine days in September
- Average UV index in September
- Average cloud cover in September
- Average visibility in September
Weather in September
Temperature
The advent of September brings an average high-temperature of a still warm 74.8°F (23.8°C), almost identical to the preceding month. During the nights in September, Jefferson experiences a consistent average temperature of 55.8°F (13.2°C).Humidity
The average relative humidity in September in Jefferson, Iowa, is 75%.Rainfall
In Jefferson, during September, the rain falls for 11.2 days and regularly aggregates up to 2.91" (74mm) of precipitation. Throughout the year, in Jefferson, there are 125.7 rainfall days, and 26.5" (673mm) of precipitation is accumulated.Snowfall
June through September are months without snowfall in Jefferson.Daylight
The average length of the day in September is 12h and 28min.On the first day of September, sunrise is at 6:43 am and sunset at 7:50 pm. On the last day of the month, sunrise is at 7:14 am and sunset at 7:00 pm CDT.
Sunshine
In September, the average sunshine is 9.3h.UV index
In Jefferson, Iowa, the average daily maximum UV index in September is 4. A UV Index of 3 to 5 symbolizes a medium health hazard from unsafe exposure to UV radiation for average individuals.Note: The maximum daily UV index of 4 in September interprets into the following recommendations:
Prioritize safety - The need to safeguard skin and eyes from harm is emphasized. The most potent solar radiation is around mid-day, so one should minimize exposure to direct sunlight during this period. For minimizing sun-related eye damage, always choose sunglasses with UVA and UVB coverage.
Frequently asked questions
What are September temperatures in Jefferson?
What is the average humidity in September in Jefferson?
How many days does it rain in September in Jefferson?
When it does not snow in Jefferson?
Does it snow in Jefferson in September?
How many hours of daylight does Jefferson have in September?
When is the sunrise / sunset in September in Jefferson?
How many hours of sunshine does Jefferson have in September?
What is the UV index intensity in September in Jefferson?
Average temperature in September
Jefferson, IA
- Average high temperature in September: 74.8°F
The warmest month (with the highest average high temperature) is July (82°F).
The month with the lowest average high temperature is January (26.8°F).
- Average low temperature in September: 55.8°F
The month with the highest average low temperature is July (64.6°F).
The coldest month (with the lowest average low temperature) is January (13.5°F).
Average pressure in September
Jefferson, IA
- Average pressure in September: 30.01"Hg
The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.88"Hg).
Average wind speed in September
Jefferson, IA
- Average wind speed in September: 8.3mph
The windiest month (with the highest average wind speed) is April (10.7mph).
The calmest months (with the lowest average wind speed) are July and August (7.1mph).
Average humidity in September
Jefferson, IA
- Average humidity in September: 75%
The month with the highest relative humidity is January (84%).
The month with the lowest relative humidity is October (69%).
Average rainfall in September
Jefferson, IA
- Average rainfall in September: 2.91"
The wettest month (with the highest rainfall) is May (4.06").
The driest month (with the least rainfall) is January (0.87").
Average rainfall days in September
Jefferson, IA
- Average rainfall days in September: 11.2 days
The month with the highest number of rainy days is June (17.3 days).
The month with the least rainy days is February (3.4 days).
Average snowfall in September
Jefferson, IA
- Average snowfall in September: 0"
The month with the highest snowfall is January (4.29").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in September
Jefferson, IA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (9.8 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Jefferson, IA
- Average daylight in September: 12h and 3min
The month with the longest days is June (Average daylight: 15h and 12min).
The month with the shortest days is December (Average daylight: 9h and 12min).
- Average sunshine in September: 9h and 2min
The month with the most sunshine is July (Average sunshine: 10h and 12min).
The month with the least sunshine is January (Average sunshine: 4h and 12min).
Average sunshine days in September
Jefferson, IA
- Average sunshine days in September: 17.2 days
The month with the most sunshine days is November (19.4 days).
The month with the least sunshine days is June (11.1 days).
Average UV index in September
Jefferson, IA
- Average UV index in September: 4
The months with the highest UV index are June and July (UV index 6).
The months with the lowest UV index are January, February, October, November and December (UV index 2).
Average cloud cover in September
Jefferson, IA
- Average cloud cover in September: 30
The month with the most cloud cover is January (Cloud cover 55).
The months with the least cloud cover are July and September (Cloud cover 30).
Average visibility in September
Jefferson, IA
- Average visibility in September: 6mi
The months with the highest visibility are February, March, April, May, June, September, October, November and December (6mi).
The months with the lowest visibility are January, July and August (5mi).
Jefferson, Iowa, USA
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