September weather forecastNorth Cascades National Park, WA
September
Weather in September
In September, the weather starts to cool down from the highs of the previous two months in North Cascades National Park. The reduction in temperature signals the approaching autumn season. Despite the cooler air, there’s still plenty of daylight and sunshine hours permitting a multitude of outdoor activities. It is still possible to enjoy hiking and camping, given the decent weather and the scenic fall colors beginning to show. However, rainfall starts to increase after the summer lull, marking the beginning of the wet season.Temperature
North Cascades National Park's progression into September includes a drop in the average high-temperature, from an agreeable 69.8°F (21°C) in August to an enjoyable 60.8°F (16°C). Compared to daytime temperatures, North Cascades National Park's temperature drops significantly, averaging a wintry 39.2°F (4°C) during the nights of September.Rainfall
In North Cascades National Park, Washington, in September, during 11 rainfall days, 2.52" (64mm) of precipitation is typically accumulated. Throughout the year, there are 157 rainfall days, and 51.02" (1296mm) of precipitation is accumulated.Daylight
In North Cascades National Park, Washington, the average length of the day in September is 12h and 34min.On the first day of the month, sunrise is at 6:23 am and sunset at 7:46 pm. On the last day of September, sunrise is at 7:04 am and sunset at 6:45 pm PDT.
Sunshine
In September, the average sunshine is 6h.UV index
In North Cascades National Park, the average daily maximum UV index in September is 5. A UV Index of 3 to 5 symbolizes a moderate health risk from unsafe exposure to UV radiation for the average person.Note: The maximum UV index of 5 during September translates into these guidelines:
Adopt protective measures - Requirement to safeguard skin and eyes from harm exists. Being in direct Sun during midday can be harmful due to intense solar radiation; take precautions. On days when the sun blazes, arm yourself with sunglasses that block UVA and UVB radiation.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
North Cascades National Park, WA
- Average high temperature in September: 61°F
The warmest months (with the highest average high temperature) are July and August (70°F).
The months with the lowest average high temperature are January and December (30°F).
- Average low temperature in September: 39°F
The months with the highest average low temperature are July and August (45°F).
The coldest months (with the lowest average low temperature) are January and December (18°F).
Average rainfall in September
North Cascades National Park, WA
- Average rainfall in September: 2.5"
The wettest month (with the highest rainfall) is December (7.8").
The driest months (with the least rainfall) are July and August (1.7").
Average rainfall days in September
North Cascades National Park, WA
- Average rainfall days in September: 11 days
The month with the highest number of rainy days is December (18 days).
The month with the least rainy days is July (8 days).
Average daylight in September /
Average sunshine in September
North Cascades National Park, WA
- Average daylight in September: 12h and 36min
The month with the longest days is June (Average daylight: 16h and 6min).
The month with the shortest days is December (Average daylight: 8h and 18min).
- Average sunshine in September: 6h
The month with the most sunshine is July (Average sunshine: 9h).
The months with the least sunshine are January, November and December (Average sunshine: 2h).
Average UV index in September
North Cascades National Park, WA
- Average UV index in September: 5
The months with the highest UV index are June, July and August (UV index 7).
The months with the lowest UV index are January, November and December (UV index 1).
