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
During Ahtanum's transition into September, the average high-temperature lessens, moving from a tropical 86.5°F (30.3°C) in August to a warm 74.8°F (23.8°C). During the month of September, Ahtanum anticipates a mean low-temperature of 53.4°F (11.9°C).Humidity
In September, the average relative humidity is 48%.Rainfall
In Ahtanum, Washington, in September, during 3.9 rainfall days, 0.24" (6mm) of precipitation is typically accumulated. Throughout the year, in Ahtanum, there are 82.2 rainfall days, and 5.43" (138mm) of precipitation is accumulated.Snowfall
January through March, September, November and December are months with snowfall. September is the first month it typically snows. Throughout September, in the average 0.1 snowfall days, it receives 0.04" (1mm) of snow. Throughout the year, there are 18.5 snowfall days, and 7.8" (198mm) of snow is accumulated.Daylight
In September, the average length of the day is 12h and 32min.On the first day of September, sunrise is at 6:23 am and sunset at 7:40 pm. On the last day of the month, sunrise is at 7:00 am and sunset at 6:43 pm PDT.
Sunshine
In Ahtanum, the average sunshine in September is 11.1h.UV index
In September, the average daily maximum UV index is 4. A UV Index reading of 3 to 5 represents a moderate threat to health from unsafe exposure to UV radiation for ordinary individuals.Note: The daily high UV index of 4 during September translates into the following recommendations:
Take necessary precautions - Defending against sun damage is advocated. Midday is the peak time for the Sun's radiation; stay in the shade and protect yourself. Clothes that are both tight-knit and comfortably loose are prime choices for sun protection. Take note! UV radiation from the Sun can double in intensity due to snow reflection.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What are the temperatures in September?
What is the average humidity in September?
How many days does it rain in September?
When does it start to snow?
What is the average length of the day in September?
When are sunrise and sunset in September?
How many hours of sunshine does Ahtanum have in September?
What is the UV index intensity in September?
Average temperature in September
Ahtanum, WA
- Average high temperature in September: 74.8°F
The warmest month (with the highest average high temperature) is August (86.5°F).
The month with the lowest average high temperature is December (36.9°F).
- Average low temperature in September: 53.4°F
The month with the highest average low temperature is August (60.3°F).
The coldest month (with the lowest average low temperature) is December (25.5°F).
Average pressure in September
Ahtanum, WA
- Average pressure in September: 29.97"Hg
The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is August (29.93"Hg).
Average wind speed in September
Ahtanum, WA
- Average wind speed in September: 6mph
The windiest month (with the highest average wind speed) is June (7.1mph).
The calmest month (with the lowest average wind speed) is December (4.4mph).
Average humidity in September
Ahtanum, WA
- Average humidity in September: 48%
The month with the highest relative humidity is January (81%).
The months with the lowest relative humidity are July and August (39%).
Average rainfall in September
Ahtanum, WA
- Average rainfall in September: 0.24"
The wettest month (with the highest rainfall) is January (0.87").
The driest month (with the least rainfall) is July (0.08").
Average rainfall days in September
Ahtanum, WA
- Average rainfall days in September: 3.9 days
The month with the highest number of rainy days is March (10.8 days).
The month with the least rainy days is August (2 days).
Average snowfall in September
Ahtanum, WA
- Average snowfall in September: 0.04"
The month with the highest snowfall is December (2.76").
The months with the least snowfall are April, May, June, July, August and October (0").
Average snowfall days in September
Ahtanum, WA
- Average snowfall days in September: 0.1 days
The month with the highest number of snowfall days is December (5.4 days).
The months with the least snowfall days are May, June, July, August and October (0 days).
Average daylight in September /
Average sunshine in September
Ahtanum, WA
- Average daylight in September: 12h and 3min
The month with the longest days is June (Average daylight: 15h and 48min).
The month with the shortest days is December (Average daylight: 8h and 36min).
- Average sunshine in September: 11h and 1min
The months with the most sunshine are July and August (Average sunshine: 12h and 6min).
The month with the least sunshine is January (Average sunshine: 5h and 36min).
Average sunshine days in September
Ahtanum, WA
- Average sunshine days in September: 23.8 days
The month with the most sunshine days is July (27.5 days).
The month with the least sunshine days is February (15.8 days).
Average UV index in September
Ahtanum, WA
- Average UV index in September: 4
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
Ahtanum, WA
- Average cloud cover in September: 14
The month with the most cloud cover is January (Cloud cover 40).
The months with the least cloud cover are July and August (Cloud cover 9).
Average visibility in September
Ahtanum, WA
- Average visibility in September: 6mi
The months with the highest visibility are February, March, April, May, June, July, August, September, October, November and December (6mi).
The month with the lowest visibility is January (5mi).
Ahtanum, Washington, USA
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