September weather forecastNampa, ID
September
Weather in September
September brings the departure of summer and welcomes the onset of autumn in Nampa. A subtle drop in temperature brings relief from the scorching heat of previous months. With declining UV index and temperatures, the evening becomes pleasant accentuating the beauty of the city. September serves as a bridge or transition between the warm summer and cooler autumn. While the daytime temperature remains warm, arrival of cooler evenings announce the advent of fall.Temperature
The average high-temperature in Nampa drops in September, from August's tropical 89.8°F (32.1°C) to a warm 79°F (26.1°C). Nampa observes a noteworthy temperature drop from the daily highs during September nights, with a mean temperature of 55.9°F (13.3°C).Humidity
The average relative humidity in September is 35%.Rainfall
In Nampa, in September, during 4.9 rainfall days, 0.2" (5mm) of precipitation is typically accumulated. In Nampa, Idaho, during the entire year, the rain falls for 98.5 days and collects up to 9.69" (246mm) of precipitation.Snowfall
In Nampa, snow does not fall in May through October.Daylight
The average length of the day in September is 12h and 29min.On the first day of the month, sunrise is at 7:11 am and sunset at 8:20 pm. On the last day of September, in Nampa, sunrise is at 7:43 am and sunset at 7:28 pm MDT.
Sunshine
In September, the average sunshine is 9.5h.UV index
In Nampa, the average daily maximum UV index in September is 5. A UV Index reading of 3 to 5 represents a medium health hazard from exposure to the Sun's UV rays for average individuals.Note: In September, the UV index of 5 transforms into the following advice:
Act with care - The need to guard against sun damage is communicated. Avoiding direct sunlight during midday hours helps reduce the risk from intense UV radiation. Wearing sunglasses with both UVA and UVB protection effectively reduces sun-induced eye damage.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Nampa, ID
- Average high temperature in September: 79°F
The warmest month (with the highest average high temperature) is July (91°F).
The month with the lowest average high temperature is December (36.5°F).
- Average low temperature in September: 55.9°F
The month with the highest average low temperature is August (63.3°F).
The coldest month (with the lowest average low temperature) is December (25.7°F).
Average pressure in September
Nampa, ID
- Average pressure in September: 29.94"Hg
The month with the highest atmospheric pressure is January (30.25"Hg).
The month with the lowest atmospheric pressure is June (29.9"Hg).
Average wind speed in September
Nampa, ID
- Average wind speed in September: 6mph
The windiest month (with the highest average wind speed) is April (7.9mph).
The calmest month (with the lowest average wind speed) is January (5.8mph).
Average humidity in September
Nampa, ID
- Average humidity in September: 35%
The month with the highest relative humidity is January (78%).
The months with the lowest relative humidity are July and August (29%).
Average rainfall in September
Nampa, ID
- Average rainfall in September: 0.2"
The wettest month (with the highest rainfall) is March (1.46").
The driest months (with the least rainfall) are July and August (0.12").
Average rainfall days in September
Nampa, ID
- Average rainfall days in September: 4.9 days
The month with the highest number of rainy days is March (14.3 days).
The month with the least rainy days is August (3.1 days).
Average snowfall in September
Nampa, ID
- Average snowfall in September: 0"
The month with the highest snowfall is January (3.23").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in September
Nampa, ID
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is December (6.6 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
Nampa, ID
- Average daylight in September: 12h and 30min
The month with the longest days is June (Average daylight: 15h and 24min).
The month with the shortest days is December (Average daylight: 9h and 0min).
- Average sunshine in September: 9h and 30min
The month with the most sunshine is July (Average sunshine: 12h and 0min).
The months with the least sunshine are January and December (Average sunshine: 5h and 48min).
Average sunshine days in September
Nampa, ID
- Average sunshine days in September: 23.3 days
The month with the most sunshine days is July (25.7 days).
The month with the least sunshine days is March (14 days).
Average UV index in September
Nampa, ID
- Average UV index in September: 5
The month with the highest UV index is July (UV index 7).
The months with the lowest UV index are January, February, November and December (UV index 2).
Average cloud cover in September
Nampa, ID
- Average cloud cover in September: 14
The months with the most cloud cover are January and December (Cloud cover 39).
The month with the least cloud cover is July (Cloud cover 8).
Average visibility in September
Nampa, ID
- Average visibility in September: 6mi
The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
