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 transition to September results in a modest reduction in average high-temperature, moving from a moderately hot 73.4°F (23°C) in August to an enjoyable 66.4°F (19.1°C). In September, the average low-temperature in Index, Washington, records at a frosty 45°F (7.2°C) during the nights.Humidity
In Index, the average relative humidity in September is 77%.Rainfall
In September, the rain falls for 12.8 days. Throughout September, 2.24" (57mm) of precipitation is accumulated. Throughout the year, in Index, there are 200.6 rainfall days, and 51.65" (1312mm) of precipitation is accumulated.Snowfall
May through October are months without snowfall.Daylight
In Index, the average length of the day in September is 12h and 33min.On the first day of September in Index, sunrise is at 6:25 am and sunset at 7:46 pm. On the last day of the month, sunrise is at 7:05 am and sunset at 6:46 pm PDT.
Sunshine
In September, the average sunshine in Index is 8.7h.UV index
In September, the average daily maximum UV index in Index is 3. A UV Index reading of 3 to 5 represents a medium vulnerability from unprotected exposure to Sun's UV rays for ordinary individuals.Note: In September, the maximum UV index of 3 suggests these recommendations:
Take measures. Individuals with light skin might experience burns in under 30 minutes. The Sun's UV radiation is especially harmful around midday, so reduce exposure and stay safe. Fend off the sun's harsh rays with appropriate clothing, a wide-brim hat, and UV-protective sunglasses.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the temperature in September in Index?
What is the average humidity in September in Index?
How much does it rain in Index in September?
When it does not snow in Index?
How many hours of daylight does Index have in September?
When is the sunrise / sunset in September in Index?
How long on average sun shines in September in Index?
What is the UV index intensity in September in Index?
Average temperature in September
Index, WA
- Average high temperature in September: 66.4°F
The warmest month (with the highest average high temperature) is August (73.4°F).
The month with the lowest average high temperature is December (38.3°F).
- Average low temperature in September: 45°F
The month with the highest average low temperature is August (48°F).
The coldest month (with the lowest average low temperature) is December (28.6°F).
Average pressure in September
Index, WA
- Average pressure in September: 30"Hg
The month with the highest atmospheric pressure is January (30.11"Hg).
The month with the lowest atmospheric pressure is August (29.99"Hg).
Average wind speed in September
Index, WA
- Average wind speed in September: 3.3mph
The windiest month (with the highest average wind speed) is January (4.8mph).
The calmest month (with the lowest average wind speed) is August (3.2mph).
Average humidity in September
Index, WA
- Average humidity in September: 77%
The months with the highest relative humidity are January, February and March (88%).
The month with the lowest relative humidity is July (72%).
Average rainfall in September
Index, WA
- Average rainfall in September: 2.24"
The wettest month (with the highest rainfall) is January (7.8").
The driest month (with the least rainfall) is August (0.79").
Average rainfall days in September
Index, WA
- Average rainfall days in September: 12.8 days
The month with the highest number of rainy days is March (22.3 days).
The month with the least rainy days is August (7.9 days).
Average snowfall in September
Index, WA
- Average snowfall in September: 0"
The month with the highest snowfall is February (5.43").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in September
Index, WA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is February (5.2 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
Index, WA
- Average daylight in September: 12h and 3min
The month with the longest days is June (Average daylight: 16h and 0min).
The month with the shortest days is December (Average daylight: 8h and 30min).
- Average sunshine in September: 8h and 4min
The month with the most sunshine is August (Average sunshine: 10h and 24min).
The months with the least sunshine are January and December (Average sunshine: 3h and 42min).
Average sunshine days in September
Index, WA
- Average sunshine days in September: 15 days
The month with the most sunshine days is August (19.9 days).
The month with the least sunshine days is March (7 days).
Average UV index in September
Index, 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, March, April, October, November and December (UV index 2).
Average cloud cover in September
Index, WA
- Average cloud cover in September: 41
The months with the most cloud cover are March and December (Cloud cover 61).
The month with the least cloud cover is August (Cloud cover 30).
Average visibility in September
Index, WA
- Average visibility in September: 5mi
The months with the highest visibility are May, June, July, August, September and October (5mi).
The months with the lowest visibility are January, February, March, April, November and December (4mi).
Index, Washington, USA
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