September weather forecastKennewick, WA
September
Weather in September
September marks the arrival of fall in Kennewick, but summer’s warmth lingers with highs of around 77.9°F (25.5°C). It’s a noticeable change from the scorching summer, but still comfortable enough for outdoor fun. Nighttime starts coming a bit earlier, inviting cool breezes into the still-warm days. The month is also characterized by stable weather, making it a great time to enjoy the city's parks and hiking trails. Fall colors start to show, adding a picturesque charm to Kennewick.Temperature
The start of September comes with a reduction in the average high-temperature, receding from a tropical 89.2°F (31.8°C) in August to a moderately hot 77.9°F (25.5°C). September nights cool down to an average low-temperature of 57°F (13.9°C).Humidity
In September, the average relative humidity is 43%.Rainfall
In Kennewick, during September, the rain falls for 4.6 days and regularly aggregates up to 0.24" (6mm) of precipitation. Throughout the year, there are 102.8 rainfall days, and 7.32" (186mm) of precipitation is accumulated.Snowfall
In Kennewick, snow does not fall in April through October.Daylight
The average length of the day in September is 12h and 31min.On the first day of September, sunrise is at 6:18 am and sunset at 7:34 pm. On the last day of the month, sunrise is at 6:54 am and sunset at 6:37 pm PDT.
Sunshine
The average sunshine in September is 10.7h.UV index
In September, the average daily maximum UV index is 5. A UV Index of 3 to 5 symbolizes a medium health hazard from unsafe exposure to UV radiation for the average person.Note: The daily high UV index of 5 during September translates into the following recommendations:
Heed the precautions - It is counselled to guard against solar damage. The solar radiation around mid-day is intense; avoid the Sun and stay safe. Consider a wide-brim hat essential for effective sun defense covering your face, neck, and eyes.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Kennewick, WA
- Average high temperature in September: 77.9°F
The warmest month (with the highest average high temperature) is July (90.1°F).
The month with the lowest average high temperature is December (38.3°F).
- Average low temperature in September: 57°F
The month with the highest average low temperature is August (64°F).
The coldest month (with the lowest average low temperature) is December (27.9°F).
Average pressure in September
Kennewick, WA
- Average pressure in September: 29.95"Hg
The month with the highest atmospheric pressure is January (30.19"Hg).
The month with the lowest atmospheric pressure is August (29.91"Hg).
Average wind speed in September
Kennewick, WA
- Average wind speed in September: 6.7mph
The windiest month (with the highest average wind speed) is April (8.5mph).
The calmest month (with the lowest average wind speed) is December (5.8mph).
Average humidity in September
Kennewick, WA
- Average humidity in September: 43%
The month with the highest relative humidity is January (80%).
The month with the lowest relative humidity is July (35%).
Average rainfall in September
Kennewick, WA
- Average rainfall in September: 0.24"
The wettest months (with the highest rainfall) are March and December (0.94").
The driest month (with the least rainfall) is July (0.2").
Average rainfall days in September
Kennewick, WA
- Average rainfall days in September: 4.6 days
The month with the highest number of rainy days is March (13.3 days).
The month with the least rainy days is July (3.5 days).
Average snowfall in September
Kennewick, WA
- Average snowfall in September: 0"
The month with the highest snowfall is February (2.2").
The months with the least snowfall are April, May, June, July, August, September and October (0").
Average snowfall days in September
Kennewick, WA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is December (3.1 days).
The months with the least snowfall days are April, May, June, July, August, September and October (0 days).
Average daylight in September /
Average sunshine in September
Kennewick, WA
- Average daylight in September: 12h and 30min
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: 10h and 42min
The month with the most sunshine is July (Average sunshine: 12h and 6min).
The month with the least sunshine is January (Average sunshine: 5h and 24min).
Average sunshine days in September
Kennewick, WA
- Average sunshine days in September: 24 days
The month with the most sunshine days is July (25.7 days).
The month with the least sunshine days is March (15.4 days).
Average UV index in September
Kennewick, WA
- Average UV index in September: 5
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
Kennewick, WA
- Average cloud cover in September: 16
The month with the most cloud cover is January (Cloud cover 44).
The month with the least cloud cover is July (Cloud cover 9).
Average visibility in September
Kennewick, WA
- Average visibility in September: 6mi
The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
