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
Letts's September weather shows a modest shift in high-temperatures, falling from August's 81.1°F (27.3°C) to a still warm 75.4°F (24.1°C). During September, the nighttime temperature in Letts averages of 56.3°F (13.5°C).Humidity
The average relative humidity in September in Letts, Iowa, is 76%.Rainfall
In September, in Letts, the rain falls for 12.3 days. Throughout September, 2.52" (64mm) of precipitation is accumulated. In Letts, during the entire year, the rain falls for 153.8 days and collects up to 31.69" (805mm) of precipitation.Snowfall
May through September are months without snowfall.Daylight
The average length of the day in September in Letts is 12h and 28min.On the first day of September in Letts, Iowa, sunrise is at 6:32 am and sunset at 7:37 pm. On the last day of the month, sunrise is at 7:01 am and sunset at 6:47 pm CDT.
Sunshine
In September, the average sunshine in Letts is 9.4h.UV index
In Letts, the average daily maximum UV index in September is 4. A UV Index value of 3 to 5 symbolizes a moderate health risk from unsafe exposure to UV radiation for the average person.Note: The maximum UV index, 4 during September, leads to the following recommendations:
Be mindful. Those with pale skin might receive burns in fewer than 30 minutes. Midday is when the Sun's radiation is strongest; avoid prolonged exposure during this time. During bright days, sunglasses that offer UVA and UVB defense are recommended.
Frequently asked questions
What is the usual temperature for Letts in September?
What is the average humidity in September in Letts?
How much does it rain in Letts in September?
When it does not snow in Letts?
Does it snow in Letts in September?
What is the average length of the day in September in Letts?
When are sunrise and sunset in September in Letts?
How long on average sun shines in September in Letts?
How high is the UV index in September in Letts?
Average temperature in September
Letts, IA
- Average high temperature in September: 75.4°F
The warmest month (with the highest average high temperature) is July (81.7°F).
The month with the lowest average high temperature is January (28.4°F).
- Average low temperature in September: 56.3°F
The month with the highest average low temperature is July (64.9°F).
The coldest month (with the lowest average low temperature) is January (16.3°F).
Average pressure in September
Letts, IA
- Average pressure in September: 30.02"Hg
The month with the highest atmospheric pressure is January (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.9"Hg).
Average wind speed in September
Letts, IA
- Average wind speed in September: 7.8mph
The windiest month (with the highest average wind speed) is April (10.6mph).
The calmest months (with the lowest average wind speed) are July and August (6.8mph).
Average humidity in September
Letts, IA
- Average humidity in September: 76%
The month with the highest relative humidity is July (83%).
The month with the lowest relative humidity is October (71%).
Average rainfall in September
Letts, IA
- Average rainfall in September: 2.52"
The wettest month (with the highest rainfall) is May (5").
The driest months (with the least rainfall) are February and December (1.46").
Average rainfall days in September
Letts, IA
- Average rainfall days in September: 12.3 days
The month with the highest number of rainy days is May (19.7 days).
The months with the least rainy days are January and February (6.3 days).
Average snowfall in September
Letts, IA
- Average snowfall in September: 0"
The month with the highest snowfall is January (4.92").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in September
Letts, IA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (12.2 days).
The months with the least snowfall days are May, June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Letts, IA
- Average daylight in September: 12h and 3min
The month with the longest days is June (Average daylight: 15h and 6min).
The month with the shortest days is December (Average daylight: 9h and 18min).
- 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
Letts, IA
- Average sunshine days in September: 15.6 days
The month with the most sunshine days is November (17.2 days).
The month with the least sunshine days is June (8.3 days).
Average UV index in September
Letts, IA
- Average UV index in September: 4
The months with the highest UV index are June, July and August (UV index 6).
The months with the lowest UV index are January and December (UV index 1).
Average cloud cover in September
Letts, IA
- Average cloud cover in September: 29
The month with the most cloud cover is January (Cloud cover 55).
The months with the least cloud cover are August and September (Cloud cover 29).
Average visibility in September
Letts, IA
- Average visibility in September: 6mi
The months with the highest visibility are January, February, March, April, May, June, August, September, October, November and December (6mi).
The month with the lowest visibility is July (5mi).
Letts, Iowa, USA
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