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
In Sumas, the beginning of September is marked by a marginally lowered average high-temperature, shifting from August's moderately hot 73.6°F (23.1°C) to an enjoyable 66.7°F (19.3°C). In the month of September, the average low-temperature usually rests at a frosty 47.5°F (8.6°C).Humidity
In Sumas, Washington, the average relative humidity in September is 78%.Rainfall
In September, the rain falls for 14.5 days. Throughout September, 2.87" (73mm) of precipitation is accumulated. Throughout the year, in Sumas, there are 188 rainfall days, and 49.88" (1267mm) of precipitation is accumulated.Snowfall
In Sumas, Washington, snow does not fall in May through October.Daylight
The average length of the day in September is 12h and 34min.On the first day of September, sunrise is at 6:26 am and sunset at 7:50 pm. On the last day of the month, sunrise is at 7:08 am and sunset at 6:49 pm PDT.
Sunshine
The average sunshine in September is 8.8h.UV index
In September, the average daily maximum UV index is 3. A UV Index estimate of 3 to 5 represents a medium health hazard from unsafe exposure to UV radiation for ordinary individuals.Note: In September, the maximum UV index of 3 translates into these guidelines:
Prioritize safety - Recommendations to avert sunburn are shared. The Sun is most powerful around mid-day, so it's a good practice to reduce direct exposure. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects.
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Data Sources | Weather Forecasting & Climate
Frequently asked questions
What are the temperatures in Sumas in September?
What is the average humidity in September in Sumas?
How much does it rain in Sumas in September?
When it does not snow in Sumas?
What is the average length of the day in September in Sumas?
What time are sunrise and sunset in September in Sumas?
How many hours of sunshine does Sumas have in September?
What is the UV index intensity in September in Sumas?
Average temperature in September
Sumas, WA
- Average high temperature in September: 66.7°F
The warmest month (with the highest average high temperature) is August (73.6°F).
The month with the lowest average high temperature is December (39.6°F).
- Average low temperature in September: 47.5°F
The month with the highest average low temperature is August (51.4°F).
The coldest months (with the lowest average low temperature) are February and December (31.6°F).
Average pressure in September
Sumas, WA
- Average pressure in September: 30.01"Hg
The month with the highest atmospheric pressure is January (30.09"Hg).
The months with the lowest atmospheric pressure are March and August (30"Hg).
Average wind speed in September
Sumas, WA
- Average wind speed in September: 3.4mph
The windiest months (with the highest average wind speed) are January and February (4.7mph).
The calmest month (with the lowest average wind speed) is August (3.2mph).
Average humidity in September
Sumas, WA
- Average humidity in September: 78%
The month with the highest relative humidity is January (87%).
The month with the lowest relative humidity is July (73%).
Average rainfall in September
Sumas, WA
- Average rainfall in September: 2.87"
The wettest month (with the highest rainfall) is November (7.72").
The driest month (with the least rainfall) is July (0.91").
Average rainfall days in September
Sumas, WA
- Average rainfall days in September: 14.5 days
The month with the highest number of rainy days is March (20.5 days).
The month with the least rainy days is August (7.8 days).
Average snowfall in September
Sumas, WA
- Average snowfall in September: 0"
The month with the highest snowfall is February (3.11").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in September
Sumas, WA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is February (4.7 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
Sumas, WA
- Average daylight in September: 12h and 4min
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: 8h and 5min
The month with the most sunshine is August (Average sunshine: 10h and 18min).
The month with the least sunshine is December (Average sunshine: 3h and 48min).
Average sunshine days in September
Sumas, WA
- Average sunshine days in September: 14.2 days
The months with the most sunshine days are July and August (21 days).
The month with the least sunshine days is March (8.4 days).
Average UV index in September
Sumas, WA
- 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, October, November and December (UV index 2).
Average cloud cover in September
Sumas, WA
- Average cloud cover in September: 39
The month with the most cloud cover is March (Cloud cover 60).
The months with the least cloud cover are July and August (Cloud cover 30).
Average visibility in September
Sumas, WA
- Average visibility in September: 5mi
The months with the highest visibility are April, May, June, July, August, September and October (5mi).
The months with the lowest visibility are January, February, March, November and December (4mi).
Sumas, Washington, USA
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