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
Saint Helens in September undergoes a slight reduction in the average high-temperature, shifting from August's moderately hot 76.5°F (24.7°C) to an agreeable 69.3°F (20.7°C). September nights see a notable contrast from daytime highs, with the nighttime temperature averaging at a chilly 45.5°F (7.5°C).Humidity
In Saint Helens, the average relative humidity in September is 77%.Rainfall
In Saint Helens, in September, it is raining for 10.5 days, with typically 1.22" (31mm) of accumulated precipitation. In Saint Helens, during the entire year, the rain falls for 149 days and collects up to 19.37" (492mm) of precipitation.Snowfall
May through October are months without snowfall.Daylight
In Saint Helens, the average length of the day in September is 12h and 31min.On the first day of the month, sunrise is at 6:33 am and sunset at 7:48 pm. On the last day of September, sunrise is at 7:09 am and sunset at 6:52 pm PDT.
Sunshine
In Saint Helens, the average sunshine in September is 8.5h.UV index
In Saint Helens, the average daily maximum UV index in September is 4. A UV Index estimate of 3 to 5 represents a medium vulnerability from exposure to the Sun's UV radiation for average individuals.Note: In September, a daily maximum UV index of 4 leads to the following instructions:
Be vigilant - Preventing sunburn is recommended. Minimize direct exposure to the Sun during midday when its radiation is at its peak. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the usual temperature for Saint Helens in September?
What is the average humidity in September?
How many days does it rain in September?
When it does not snow?
What is the average length of the day in September?
What time are sunrise and sunset in September?
How many hours of sunshine does Saint Helens have in September?
What is the UV index reading in September in Saint Helens?
Average temperature in September
Saint Helens, OR
- Average high temperature in September: 69.3°F
The warmest month (with the highest average high temperature) is August (76.5°F).
The month with the lowest average high temperature is December (41.9°F).
- Average low temperature in September: 45.5°F
The month with the highest average low temperature is August (47.8°F).
The coldest month (with the lowest average low temperature) is December (31.8°F).
Average pressure in September
Saint Helens, OR
- Average pressure in September: 30.01"Hg
The month with the highest atmospheric pressure is January (30.11"Hg).
The months with the lowest atmospheric pressure are August and September (30.01"Hg).
Average wind speed in September
Saint Helens, OR
- Average wind speed in September: 3.7mph
The windiest month (with the highest average wind speed) is January (5.3mph).
The calmest month (with the lowest average wind speed) is August (3.5mph).
Average humidity in September
Saint Helens, OR
- Average humidity in September: 77%
The month with the highest relative humidity is February (88%).
The months with the lowest relative humidity are July and August (72%).
Average rainfall in September
Saint Helens, OR
- Average rainfall in September: 1.22"
The wettest month (with the highest rainfall) is January (2.64").
The driest month (with the least rainfall) is July (0.31").
Average rainfall days in September
Saint Helens, OR
- Average rainfall days in September: 10.5 days
The month with the highest number of rainy days is March (16 days).
The month with the least rainy days is July (5.9 days).
Average snowfall in September
Saint Helens, OR
- Average snowfall in September: 0"
The month with the highest snowfall is January (1.97").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in September
Saint Helens, OR
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is February (3.6 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).
Average daylight in September /
Average sunshine in September
Saint Helens, OR
- Average daylight in September: 12h and 3min
The month with the longest days is June (Average daylight: 15h and 42min).
The month with the shortest days is December (Average daylight: 8h and 42min).
- Average sunshine in September: 8h and 3min
The month with the most sunshine is August (Average sunshine: 10h and 24min).
The months with the least sunshine are January, February and December (Average sunshine: 3h and 42min).
Average sunshine days in September
Saint Helens, OR
- Average sunshine days in September: 18.2 days
The month with the most sunshine days is July (23.7 days).
The month with the least sunshine days is February (12.1 days).
Average UV index in September
Saint Helens, OR
- Average UV index in September: 4
The month with the highest UV index is July (UV index 5).
The month with the lowest UV index is November (UV index 1).
Average cloud cover in September
Saint Helens, OR
- Average cloud cover in September: 42
The month with the most cloud cover is March (Cloud cover 63).
The month with the least cloud cover is August (Cloud cover 32).
Average visibility in September
Saint Helens, OR
- Average visibility in September: 4mi
The months with the highest visibility are July and August (5mi).
The months with the lowest visibility are January, February, March, April, May, June, September, October, November and December (4mi).
Saint Helens, Oregon, USA
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