September weather forecastRiverside, OR
September
Weather in September
September, the first month of the autumn in Riverside, is still a pleasant month, with an average temperature ranging between max 73°F (22.8°C) and min 51.8°F (11°C).Temperature
The arrival of September corresponds with a reduction in the average high-temperature, down from August's moderately hot 83.5°F (28.6°C) to an agreeable 73°F (22.8°C). Nighttime temperatures in September average to a fresh 51.8°F (11°C).Humidity
In Riverside, Oregon, the average relative humidity in September is 38%.Rainfall
In September, the rain falls for 5.5 days. Throughout September, 0.59" (15mm) of precipitation is accumulated. Throughout the year, there are 109.9 rainfall days, and 11.34" (288mm) of precipitation is accumulated.Snowfall
In Riverside, snow does not fall in June through October.Daylight
The average length of the day in September is 12h and 29min.On the first day of the month, sunrise is at 7:17 am and sunset at 8:27 pm. On the last day of September, sunrise is at 7:49 am and sunset at 7:34 pm MDT.
Sunshine
In Riverside, the average sunshine in September is 9.5h.UV index
In September, the average daily maximum UV index is 4. A UV Index reading of 3 to 5 represents a medium health hazard from unsafe exposure to UV radiation for the ordinary person.Note: The maximum UV index of 4 during September translates into these guidelines:
Preventative actions are necessary - Recommendations to ward off sunburn are given. The solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. A wide-brimmed hat is a staple for defending the face, eyes, ears, and neck from the Sun.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Riverside, OR
- Average high temperature in September: 73°F
The warmest month (with the highest average high temperature) is July (85.3°F).
The month with the lowest average high temperature is December (31.8°F).
- Average low temperature in September: 51.8°F
The month with the highest average low temperature is August (59°F).
The coldest month (with the lowest average low temperature) is January (19.2°F).
Average pressure in September
Riverside, OR
- Average pressure in September: 29.96"Hg
The month with the highest atmospheric pressure is January (30.23"Hg).
The months with the lowest atmospheric pressure are June and August (29.93"Hg).
Average wind speed in September
Riverside, OR
- Average wind speed in September: 6.4mph
The windiest month (with the highest average wind speed) is April (7.8mph).
The calmest month (with the lowest average wind speed) is January (5mph).
Average humidity in September
Riverside, OR
- Average humidity in September: 38%
The month with the highest relative humidity is January (85%).
The months with the lowest relative humidity are July and August (31%).
Average rainfall in September
Riverside, OR
- Average rainfall in September: 0.59"
The wettest month (with the highest rainfall) is December (1.77").
The driest month (with the least rainfall) is July (0.12").
Average rainfall days in September
Riverside, OR
- Average rainfall days in September: 5.5 days
The month with the highest number of rainy days is March (15.3 days).
The month with the least rainy days is July (3.4 days).
Average snowfall in September
Riverside, OR
- Average snowfall in September: 0"
The month with the highest snowfall is December (9.13").
The months with the least snowfall are June, July, August, September and October (0").
Average snowfall days in September
Riverside, OR
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is December (13.1 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Riverside, OR
- Average daylight in September: 12h and 30min
The month with the longest days is June (Average daylight: 15h and 24min).
The month with the shortest days is December (Average daylight: 9h and 0min).
- Average sunshine in September: 9h and 30min
The month with the most sunshine is July (Average sunshine: 12h and 0min).
The month with the least sunshine is December (Average sunshine: 5h and 6min).
Average sunshine days in September
Riverside, OR
- Average sunshine days in September: 22.1 days
The month with the most sunshine days is July (25.3 days).
The month with the least sunshine days is March (11.5 days).
Average UV index in September
Riverside, OR
- Average UV index in September: 4
The month with the highest UV index is July (UV index 7).
The months with the lowest UV index are January, February, March, November and December (UV index 2).
Average cloud cover in September
Riverside, OR
- Average cloud cover in September: 14
The months with the most cloud cover are January and December (Cloud cover 47).
The month with the least cloud cover is July (Cloud cover 8).
Average visibility in September
Riverside, OR
- Average visibility in September: 6mi
The months with the highest visibility are March, April, May, June, July, August, September, October and November (6mi).
The month with the lowest visibility is January (4mi).
