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
The shift from August to September coincides with a small decrease in the average high-temperature, down to a pleasant 68.4°F (20.2°C) from a moderately hot 75.4°F (24.1°C). Black Diamond's average low-temperature is measured at a chilly 47.3°F (8.5°C) during September.Humidity
The average relative humidity in September is 75%.Rainfall
In September, the rain falls for 11.9 days. Throughout September, 1.73" (44mm) of precipitation is accumulated. Throughout the year, in Black Diamond, there are 182.4 rainfall days, and 36.77" (934mm) of precipitation is accumulated.Snowfall
May through October are months without snowfall in Black Diamond.Daylight
The average length of the day in September is 12h and 32min.On the first day of September, sunrise is at 6:28 am and sunset at 7:47 pm. On the last day of the month, sunrise is at 7:06 am and sunset at 6:48 pm PDT.
Sunshine
The average sunshine in September in Black Diamond is 9.1h.UV index
In September, the average daily maximum UV index is 3. A UV Index reading of 3 to 5 represents a moderate health risk from exposure to the Sun's UV radiation for the average person.Note: A maximum UV index of 3 in September translates into the following recommendations:
Undertake protective steps - Recommendations to avoid sunburn are issued. Solar radiation is at its peak intensity during midday, so it's advisable to stay indoors or in the shade. For optimum UV protection, wear sun-resistant attire complemented with a hat and quality shades. Be on the lookout! Nearly twofold UV radiation from the Sun can be reflected by snow.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the usual temperature for Black Diamond in September?
What is the average humidity in September in Black Diamond?
How many days does it rain in September in Black Diamond?
When it does not snow in Black Diamond?
What is the average length of the day in September in Black Diamond?
When are sunrise and sunset in September in Black Diamond?
How long on average sun shines in September in Black Diamond?
What is the UV index intensity in September in Black Diamond?
Average temperature in September
Black Diamond, WA
- Average high temperature in September: 68.4°F
The warmest month (with the highest average high temperature) is August (75.4°F).
The month with the lowest average high temperature is December (40.8°F).
- Average low temperature in September: 47.3°F
The month with the highest average low temperature is August (50.2°F).
The coldest month (with the lowest average low temperature) is February (31.6°F).
Average pressure in September
Black Diamond, WA
- Average pressure in September: 30"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"Hg).
Average wind speed in September
Black Diamond, WA
- Average wind speed in September: 3.7mph
The windiest month (with the highest average wind speed) is January (5.2mph).
The calmest month (with the lowest average wind speed) is August (3.5mph).
Average humidity in September
Black Diamond, WA
- Average humidity in September: 75%
The months with the highest relative humidity are January and February (86%).
The month with the lowest relative humidity is July (70%).
Average rainfall in September
Black Diamond, WA
- Average rainfall in September: 1.73"
The wettest month (with the highest rainfall) is December (5.43").
The driest month (with the least rainfall) is July (0.59").
Average rainfall days in September
Black Diamond, WA
- Average rainfall days in September: 11.9 days
The month with the highest number of rainy days is March (20.5 days).
The month with the least rainy days is August (6.7 days).
Average snowfall in September
Black Diamond, WA
- Average snowfall in September: 0"
The month with the highest snowfall is February (4.17").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in September
Black Diamond, WA
- Average snowfall days in September: 0.1 days
The month with the highest number of snowfall days is February (6 days).
The months with the least snowfall days are June, July, August and October (0 days).
Average daylight in September /
Average sunshine in September
Black Diamond, WA
- Average daylight in September: 12h and 3min
The month with the longest days is June (Average daylight: 15h and 54min).
The month with the shortest days is December (Average daylight: 8h and 30min).
- Average sunshine in September: 9h and 1min
The month with the most sunshine is August (Average sunshine: 10h and 42min).
The months with the least sunshine are January and December (Average sunshine: 4h and 6min).
Average sunshine days in September
Black Diamond, WA
- Average sunshine days in September: 16.8 days
The month with the most sunshine days is August (22 days).
The month with the least sunshine days is February (8.4 days).
Average UV index in September
Black Diamond, WA
- Average UV index in September: 3
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
Black Diamond, WA
- Average cloud cover in September: 37
The months with the most cloud cover are January, February, March and December (Cloud cover 57).
The month with the least cloud cover is August (Cloud cover 27).
Average visibility in September
Black Diamond, WA
- Average visibility in September: 5mi
The months with the highest visibility are July and August (6mi).
The months with the lowest visibility are January, February and December (4mi).
Black Diamond, Washington, USA
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