September weather forecastHillsboro, OR
September
Weather in September
September represents a noticeable transitional weather phase in Hillsboro with temperatures beginning to cool, falling to an average high of around 73.9°F (23.3°C). The receding summer heat and the early onset of fall create a comfortable environment, allowing flora and fauna to thrive. Days start shortening, as the rain makes a slow return, imitating the drizzle typical of the city. Despite this, the amount of sunshine remains high providing plenty of opportunities for residents to experience outdoor activities. The moderate weather and the hint of arriving fall offer a captivating blend of remaining warm days and an increasing freshness in the air.Temperature
September witnesses a gentle descent in average high-temperature, descending from August's warm 81.5°F (27.5°C) to a still moderately hot 73.9°F (23.3°C). Hillsboro experiences a significant reduction from daytime highs with an average low-temperature of 51.4°F (10.8°C) in September.Humidity
In Hillsboro, the average relative humidity in September is 70%.Rainfall
In Hillsboro, in September, during 10.1 rainfall days, 1.46" (37mm) of precipitation is typically accumulated. Throughout the year, there are 173 rainfall days, and 29.49" (749mm) of precipitation is accumulated.Snowfall
In Hillsboro, 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 the month, sunrise is at 6:34 am and sunset at 7:48 pm. On the last day of September, sunrise is at 7:10 am and sunset at 6:53 pm PDT.
Sunshine
In September, the average sunshine is 8.9h.UV index
The average daily maximum UV index in September is 4. A UV Index value of 3 to 5 symbolizes a moderate health risk from exposure to the Sun's UV radiation for the average person.Note: In September, the maximum UV index of 4 transforms into these recommendations:
Take heed. Individuals of lighter complexion can be burned in less than half an hour. Given the potency of the midday Sun's UV radiation, one should avoid prolonged exposure. Sunglasses that guard against UVA and UVB rays are pivotal in minimizing sun-induced ocular damage.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Hillsboro, OR
- Average high temperature in September: 73.9°F
The warmest month (with the highest average high temperature) is August (81.5°F).
The month with the lowest average high temperature is December (43.9°F).
- Average low temperature in September: 51.4°F
The month with the highest average low temperature is August (55.4°F).
The coldest month (with the lowest average low temperature) is December (34°F).
Average pressure in September
Hillsboro, OR
- Average pressure in September: 30.01"Hg
The month with the highest atmospheric pressure is January (30.11"Hg).
The months with the lowest atmospheric pressure are August and September (30.01"Hg).
Average wind speed in September
Hillsboro, OR
- Average wind speed in September: 4.3mph
The windiest month (with the highest average wind speed) is March (5mph).
The calmest months (with the lowest average wind speed) are June, August and September (4.3mph).
Average humidity in September
Hillsboro, OR
- Average humidity in September: 70%
The months with the highest relative humidity are January, February, November and December (85%).
The month with the lowest relative humidity is August (64%).
Average rainfall in September
Hillsboro, OR
- Average rainfall in September: 1.46"
The wettest month (with the highest rainfall) is January (4.57").
The driest month (with the least rainfall) is August (0.31").
Average rainfall days in September
Hillsboro, OR
- Average rainfall days in September: 10.1 days
The month with the highest number of rainy days is March (20.8 days).
The month with the least rainy days is August (4.4 days).
Average snowfall in September
Hillsboro, OR
- Average snowfall in September: 0"
The month with the highest snowfall is February (1.81").
The months with the least snowfall are April, May, June, July, August, September and October (0").
Average snowfall days in September
Hillsboro, OR
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is February (2.4 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
Hillsboro, OR
- Average daylight in September: 12h and 30min
The month with the longest days is June (Average daylight: 15h and 36min).
The month with the shortest days is December (Average daylight: 8h and 48min).
- Average sunshine in September: 8h and 54min
The month with the most sunshine is August (Average sunshine: 10h and 36min).
The month with the least sunshine is February (Average sunshine: 3h and 42min).
Average sunshine days in September
Hillsboro, OR
- Average sunshine days in September: 17.2 days
The month with the most sunshine days is July (24.4 days).
The month with the least sunshine days is March (8.5 days).
Average UV index in September
Hillsboro, OR
- Average UV index in September: 4
The month with the highest UV index is July (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 2).
Average cloud cover in September
Hillsboro, OR
- Average cloud cover in September: 36
The month with the most cloud cover is February (Cloud cover 63).
The month with the least cloud cover is August (Cloud cover 25).
Average visibility in September
Hillsboro, OR
- Average visibility in September: 6mi
The months with the highest visibility are July, August and September (6mi).
The months with the lowest visibility are January and February (4mi).
