September weather forecast
Redmond, WA

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Weather in September

September marks the beginning of autumn, wherein Redmond witnesses a slow fall in temperatures. The scorching heat dares to linger but eventually makes way for the cool fall breeze. September serves as a transition with days shortening and once constant sunshine starting to fade. After August's crescendo, rainfall also experiences a brisk increase to 1.57" (40mm), indicating the end of summer's drought. The wind picks up again, creating rustling melodies as it roams through falling autumn leaves.

Temperature

Redmond in September experiences a gentle temperature dip, with average high-temperatures reducing from a warm 76.3°F (24.6°C) in August to a pleasant 69.3°F (20.7°C). Redmond's temperature lowers to a mean of 49.1°F (9.5°C) during the nights in September.

Humidity

The average relative humidity in September is 75%.

Rainfall

In Redmond, during September, the rain falls for 11.4 days and regularly aggregates up to 1.57" (40mm) of precipitation. In Redmond, Washington, during the entire year, the rain falls for 174 days and collects up to 29.69" (754mm) of precipitation.

Snowfall

April through October are months without snowfall.

Daylight

In September, the average length of the day is 12h and 33min.
On the first day of the month, sunrise is at 6:28 am and sunset at 7:48 pm. On the last day of September, sunrise is at 7:07 am and sunset at 6:49 pm PDT.

Sunshine

The average sunshine in September is 9.4h.

UV index

In Redmond, Washington, the average daily maximum UV index in September is 3. A UV Index value of 3 to 5 symbolizes a medium vulnerability from exposure to the Sun's UV radiation for ordinary individuals.
Note: In September, an average UV index of 3 transforms into the following instructions:
Take precautions - Protection against skin and eye damage is obliged. Midday Sun has the strongest UV rays, making it crucial to limit exposure and find shade. Experience reduced UV exposure by about half when donning a wide-brim hat.
Updated: Jul 14, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What are September temperatures?

The high-temperature, in September, in Redmond, records 69.3°F (20.7°C), while the low-temperature is 49.1°F (9.5°C).

What is the average humidity in September in Redmond?

The average relative humidity in September is 75%.

How many days does it rain in September?

In Redmond, in September, it is raining for 11.4 days, with typically 1.57" (40mm) of accumulated precipitation.

When it does not snow?

In Redmond, snow does not fall in April through October.

How many hours of daylight does Redmond have in September?

In Redmond, the average day length in September is 12h and 33min.

When are sunrise and sunset in September?

On the first day of September, sunrise is at 6:28 am and sunset at 7:48 pm. On the last day of the month, sunrise is at 7:07 am and sunset at 6:49 pm PDT.

How long on average sun shines in September?

In Redmond, the average sunshine duration in September is 9.4h.

What is the UV index intensity in September?

In Redmond, the average daily maximum UV index in September is 3. A UV Index reading of 3 to 5 represents a moderate vulnerability from unprotected exposure to UV radiation.
Average humidity
Average rainfall days
Average snowfall
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
Redmond, WA

Average temperature in September - Redmond, WA
  • Average high temperature in September: 69.3°F

The warmest month (with the highest average high temperature) is August (76.3°F).
The month with the lowest average high temperature is December (42.1°F).

  • Average low temperature in September: 49.1°F

The month with the highest average low temperature is August (52.5°F).
The coldest month (with the lowest average low temperature) is December (34°F).

Average pressure in September
Redmond, WA

Average pressure in September - Redmond, WA
  • Average pressure in September: 30.01"Hg

The month with the highest atmospheric pressure is January (30.1"Hg).
The month with the lowest atmospheric pressure is August (30"Hg).

Average wind speed in September
Redmond, WA

Average wind speed in September - Redmond, WA
  • Average wind speed in September: 3.7mph

The windiest months (with the highest average wind speed) are January and March (5mph).
The calmest months (with the lowest average wind speed) are July and August (3.4mph).

Average humidity in September
Redmond, WA

Average humidity in September - Redmond, WA
  • Average humidity in September: 75%

The months with the highest relative humidity are January, February and December (85%).
The month with the lowest relative humidity is July (70%).

Average rainfall in September
Redmond, WA

Average rainfall in September - Redmond, WA
  • Average rainfall in September: 1.57"

The wettest month (with the highest rainfall) is December (4.37").
The driest month (with the least rainfall) is July (0.39").

Average rainfall days in September
Redmond, WA

Average rainfall days in September - Redmond, WA
  • Average rainfall days in September: 11.4 days

The month with the highest number of rainy days is March (19.7 days).
The month with the least rainy days is August (5.9 days).

Average snowfall in September
Redmond, WA

Average snowfall in September - Redmond, WA
  • Average snowfall in September: 0"

The month with the highest snowfall is February (2.05").
The months with the least snowfall are April, May, June, July, August, September and October (0").

Average snowfall days in September
Redmond, WA

Average snowfall days in September - Redmond, WA
  • Average snowfall days in September: 0 days

The month with the highest number of snowfall days is February (3.2 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
Redmond, WA

Average daylight in September / Average sunshine in September - Redmond, WA
  • Average daylight in September: 12h and 3min

The month with the longest days is June (Average daylight: 15h and 54min).
The month with the shortest days is December (Average daylight: 8h and 30min).

  • Average sunshine in September: 9h and 2min

The month with the most sunshine is August (Average sunshine: 10h and 42min).
The month with the least sunshine is December (Average sunshine: 4h and 12min).

Average sunshine days in September
Redmond, WA

Average sunshine days in September - Redmond, WA
  • Average sunshine days in September: 16.4 days

The month with the most sunshine days is August (23.3 days).
The month with the least sunshine days is February (8.8 days).

Average UV index in September
Redmond, WA

Average UV index in September - Redmond, 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, November and December (UV index 2).

Average cloud cover in September
Redmond, WA

Average cloud cover in September - Redmond, WA
  • Average cloud cover in September: 34

The months with the most cloud cover are January and December (Cloud cover 56).
The month with the least cloud cover is August (Cloud cover 25).

Average visibility in September
Redmond, WA

Average visibility in September - Redmond, WA
  • Average visibility in September: 6mi

The months with the highest visibility are June, July, August and September (6mi).
The months with the lowest visibility are January, February, March, April, May, October, November and December (5mi).

Redmond, Washington, USA

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