September weather forecastPorthill, ID
September
Weather in September
The first month of the autumn, September, is still a refreshing month in Porthill, Idaho, with an average temperature fluctuating between 39.9°F (4.4°C) and 65.8°F (18.8°C).Temperature
The onset of September coincides with a reduction in the average high-temperature, falling from a warm 76.3°F (24.6°C) in August to an enjoyable 65.8°F (18.8°C). Despite the significant gap from daytime peaks, Porthill experiences an average low-temperature of 39.9°F (4.4°C) in September.Humidity
In Porthill, the average relative humidity in September is 64%.Rainfall
In September, the rain falls for 9.5 days. Throughout September, 0.87" (22mm) of precipitation is accumulated. In Porthill, during the entire year, the rain falls for 157.1 days and collects up to 21.61" (549mm) of precipitation.Snowfall
January through April, September through December are months with snowfall. September is the first month it typically snows. Throughout September, in the average 0.3 snowfall days, it receives 0.51" (13mm) of snow. Throughout the year, there are 70.6 snowfall days, and 41.77" (1061mm) of snow is accumulated.Daylight
In Porthill, the average length of the day in September is 12h and 34min.On the first day of the month, sunrise is at 7:03 am and sunset at 8:27 pm. On the last day of September, sunrise is at 7:45 am and sunset at 7:26 pm MDT.
Sunshine
In September, the average sunshine is 9.7h.UV index
The average daily maximum UV index in September is 3. A UV Index estimate of 3 to 5 represents a moderate threat to health from exposure to the Sun's UV rays for ordinary individuals.Note: A daily high UV index of 3 in September leads to these guidelines:
Take measures. Individuals with light skin might experience burns in under 30 minutes. When the Sun is at its strongest around midday, find shade and limit exposure. Wearing a wide-brim hat can block approximately 50% of UV radiation, protecting the eyes. Alert! The snow's reflection can amplify the UV radiation of the Sun nearly twice.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Porthill, ID
- Average high temperature in September: 65.8°F
The warmest month (with the highest average high temperature) is August (76.3°F).
The month with the lowest average high temperature is December (27.3°F).
- Average low temperature in September: 39.9°F
The month with the highest average low temperature is August (47.7°F).
The coldest months (with the lowest average low temperature) are January and December (16.3°F).
Average pressure in September
Porthill, ID
- Average pressure in September: 29.98"Hg
The month with the highest atmospheric pressure is January (30.19"Hg).
The month with the lowest atmospheric pressure is June (29.91"Hg).
Average wind speed in September
Porthill, ID
- Average wind speed in September: 3.7mph
The windiest month (with the highest average wind speed) is June (4.3mph).
The calmest month (with the lowest average wind speed) is December (3.5mph).
Average humidity in September
Porthill, ID
- Average humidity in September: 64%
The month with the highest relative humidity is January (94%).
The month with the lowest relative humidity is August (55%).
Average rainfall in September
Porthill, ID
- Average rainfall in September: 0.87"
The wettest month (with the highest rainfall) is December (2.76").
The driest month (with the least rainfall) is August (0.43").
Average rainfall days in September
Porthill, ID
- Average rainfall days in September: 9.5 days
The month with the highest number of rainy days is April (19.7 days).
The month with the least rainy days is August (6.5 days).
Average snowfall in September
Porthill, ID
- Average snowfall in September: 0.51"
The month with the highest snowfall is January (11.02").
The months with the least snowfall are May, June, July and August (0").
Average snowfall days in September
Porthill, ID
- Average snowfall days in September: 0.3 days
The month with the highest number of snowfall days is December (17.4 days).
The months with the least snowfall days are May, June, July and August (0 days).
Average daylight in September /
Average sunshine in September
Porthill, ID
- Average daylight in September: 12h and 36min
The month with the longest days is June (Average daylight: 16h and 6min).
The month with the shortest days is December (Average daylight: 8h and 18min).
- Average sunshine in September: 9h and 42min
The month with the most sunshine is August (Average sunshine: 11h and 54min).
The month with the least sunshine is January (Average sunshine: 3h and 48min).
Average sunshine days in September
Porthill, ID
- Average sunshine days in September: 18 days
The month with the most sunshine days is August (21.8 days).
The month with the least sunshine days is March (7.7 days).
Average UV index in September
Porthill, ID
- Average UV index in September: 3
The month with the highest UV index is July (UV index 5).
The months with the lowest UV index are January, February, November and December (UV index 1).
Average cloud cover in September
Porthill, ID
- Average cloud cover in September: 25
The month with the most cloud cover is January (Cloud cover 62).
The month with the least cloud cover is August (Cloud cover 15).
Average visibility in September
Porthill, ID
- Average visibility in September: 6mi
The months with the highest visibility are May, June, July, August and September (6mi).
The month with the lowest visibility is January (2mi).
