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
Lewiston's transition into September involves a shift in temperature, receding from a warm 81.1°F (27.3°C) in August to an agreeable 71.2°F (21.8°C). Lewiston encounters a substantial decline from its daily high to a low-temperature of 46.8°F (8.2°C) during September nights.Humidity
In Lewiston, the average relative humidity in September is 45%.Rainfall
In September, the rain falls for 8.7 days. Throughout September, 1.06" (27mm) of precipitation is accumulated. In Lewiston, during the entire year, the rain falls for 117.9 days and collects up to 17.68" (449mm) of precipitation.Snowfall
Months with snowfall are January through May, September through December. September is the first month it typically snows. Throughout September, in the average 0.1 snowfall days, it receives 0.2" (5mm) of snow. In Lewiston, during the entire year, snow falls for 71.1 days and aggregates up to 56.1" (1425mm) of snow.Daylight
In Lewiston, the average length of the day in September is 12h and 28min.On the first day of the month, sunrise is at 6:53 am and sunset at 8:00 pm. On the last day of September, sunrise is at 7:24 am and sunset at 7:10 pm MDT.
Sunshine
The average sunshine in September in Lewiston is 10h.UV index
In September, the average daily maximum UV index is 3. A UV Index of 3 to 5 symbolizes a moderate threat to health from exposure to the Sun's UV rays for the average person.Note: In September, the maximum UV index of 3 translates into these guidelines:
Heed the precautions - It is counselled to guard against solar damage. UV radiation from the Sun is most dangerous during midday; take precautions and seek shade. For effective sun eye protection, rely on sunglasses certified for UVA and UVB resistance. Warning! The reflection from snow can nearly magnify the Sun's UV radiation twofold.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the usual temperature for Lewiston in September?
What is the average humidity in September in Lewiston?
How much does it rain in Lewiston in September?
When does it start to snow in Lewiston?
What is the average length of the day in September in Lewiston?
When is the sunrise / sunset in September in Lewiston?
How many hours of sunshine does Lewiston have in September?
How high is the UV index in September in Lewiston?
Average temperature in September
Lewiston, UT
- Average high temperature in September: 71.2°F
The warmest month (with the highest average high temperature) is July (82.8°F).
The month with the lowest average high temperature is December (28.6°F).
- Average low temperature in September: 46.8°F
The month with the highest average low temperature is July (55.4°F).
The coldest month (with the lowest average low temperature) is January (13.6°F).
Average pressure in September
Lewiston, UT
- Average pressure in September: 29.96"Hg
The month with the highest atmospheric pressure is January (30.29"Hg).
The month with the lowest atmospheric pressure is June (29.89"Hg).
Average wind speed in September
Lewiston, UT
- Average wind speed in September: 5.3mph
The windiest months (with the highest average wind speed) are April, June and August (5.7mph).
The calmest month (with the lowest average wind speed) is January (4.2mph).
Average humidity in September
Lewiston, UT
- Average humidity in September: 45%
The month with the highest relative humidity is January (90%).
The month with the lowest relative humidity is August (38%).
Average rainfall in September
Lewiston, UT
- Average rainfall in September: 1.06"
The wettest month (with the highest rainfall) is January (2.24").
The driest month (with the least rainfall) is July (0.63").
Average rainfall days in September
Lewiston, UT
- Average rainfall days in September: 8.7 days
The month with the highest number of rainy days is May (14.9 days).
The month with the least rainy days is November (6.7 days).
Average snowfall in September
Lewiston, UT
- Average snowfall in September: 0.2"
The month with the highest snowfall is January (16.73").
The months with the least snowfall are June, July and August (0").
Average snowfall days in September
Lewiston, UT
- Average snowfall days in September: 0.1 days
The month with the highest number of snowfall days is January (15.9 days).
The months with the least snowfall days are July and August (0 days).
Average daylight in September /
Average sunshine in September
Lewiston, UT
- 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: 10h and 0min
The months with the most sunshine are July and August (Average sunshine: 11h and 54min).
The month with the least sunshine is January (Average sunshine: 4h and 48min).
Average sunshine days in September
Lewiston, UT
- Average sunshine days in September: 17.5 days
The month with the most sunshine days is October (19.4 days).
The month with the least sunshine days is February (9.1 days).
Average UV index in September
Lewiston, UT
- Average UV index in September: 3
The month with the highest UV index is July (UV index 6).
The months with the lowest UV index are January and December (UV index 1).
Average cloud cover in September
Lewiston, UT
- Average cloud cover in September: 15
The month with the most cloud cover is February (Cloud cover 52).
The month with the least cloud cover is August (Cloud cover 10).
Average visibility in September
Lewiston, UT
- Average visibility in September: 6mi
The months with the highest visibility are April, May, June, July, August, September, October and November (6mi).
The months with the lowest visibility are January, February and December (4mi).
Lewiston, Utah, USA
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