September weather forecast
Hamilton, WA

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Weather in September

The first month of the autumn, September, is still a refreshing month in Hamilton, Washington, with temperature in the range of an average high of 64.2°F (17.9°C) and an average low of 47.8°F (8.8°C).

Temperature

As August transitions into September, Hamilton sees a gentle drop in the average high-temperature, transitioning from a pleasant 70.7°F (21.5°C) to a comfortable 64.2°F (17.9°C). Throughout September, an average low-temperature of 47.8°F (8.8°C) is expected in Hamilton.

Humidity

In September, the average relative humidity is 79%.

Rainfall

In September, in Hamilton, the rain falls for 13.5 days. Throughout September, 2.76" (70mm) of precipitation is accumulated. Throughout the year, in Hamilton, there are 203.2 rainfall days, and 49.72" (1263mm) of precipitation is accumulated.

Snowfall

May through October are months without snowfall in Hamilton.

Daylight

The average length of the day in September is 12h and 34min.
On the first day of September, sunrise is at 6:26 am and sunset at 7:48 pm. On the last day of the month, sunrise is at 7:07 am and sunset at 6:48 pm PDT.

Sunshine

In September, the average sunshine is 8.8h.

UV index

In Hamilton, the average daily maximum UV index in September is 3. A UV Index value of 3 to 5 symbolizes a moderate health risk from exposure to the Sun's UV radiation for the ordinary person.
Note: During September, 3 as the daily maximum UV index converts into the following advice:
Make use of precautions - It is urged to ward off sun damage. To guard against the harmful effects of the Sun, minimize exposure during midday. In the presence of strong sunlight, it's crucial to wear sunglasses that ward off UVA and UVB rays.
Updated: Feb 14, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What is the usual temperature for Hamilton in September?

In Hamilton, 64.2°F (17.9°C) is the average high-temperature and 47.8°F (8.8°C) is the average low-temperature during September.

What is the average humidity in September in Hamilton?

The average relative humidity in September is 79%.

How much does it rain in Hamilton in September?

In Hamilton, Washington, in September, it is raining for 13.5 days, with typically 2.76" (70mm) of accumulated precipitation.

When it does not snow in Hamilton?

In Hamilton, snow does not fall in May through October.

What is the average length of the day in September in Hamilton?

The average day length in September in Hamilton is 12h and 34min.

What time are sunrise and sunset in September in Hamilton?

In September, on the first day of the month, sunrise is at 6:26 am and sunset at 7:48 pm. On the last day of the month, in Hamilton, Washington, sunrise is at 7:07 am and sunset at 6:48 pm PDT.

How many hours of sunshine does Hamilton have in September?

In Hamilton, Washington, the average sunshine duration in September is 8.8h.

How high is the UV index in September in Hamilton?

The average daily maximum UV index in September in Hamilton is 3. A UV Index reading of 3 to 5 represents a medium hazard to health 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
Hamilton, WA

Average temperature in September - Hamilton, WA
  • Average high temperature in September: 64.2°F

The warmest month (with the highest average high temperature) is July (70.9°F).
The month with the lowest average high temperature is December (40.5°F).

  • Average low temperature in September: 47.8°F

The month with the highest average low temperature is August (50.5°F).
The coldest months (with the lowest average low temperature) are February and December (32.5°F).

Average pressure in September
Hamilton, WA

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

The month with the highest atmospheric pressure is January (30.09"Hg).
The month with the lowest atmospheric pressure is August (30"Hg).

Average wind speed in September
Hamilton, WA

Average wind speed in September - Hamilton, WA
  • Average wind speed in September: 3.8mph

The windiest month (with the highest average wind speed) is November (5.7mph).
The calmest month (with the lowest average wind speed) is August (3.3mph).

Average humidity in September
Hamilton, WA

Average humidity in September - Hamilton, WA
  • Average humidity in September: 79%

The months with the highest relative humidity are January, February and March (86%).
The month with the lowest relative humidity is July (75%).

Average rainfall in September
Hamilton, WA

Average rainfall in September - Hamilton, WA
  • Average rainfall in September: 2.76"

The wettest month (with the highest rainfall) is November (7.09").
The driest month (with the least rainfall) is July (0.98").

Average rainfall days in September
Hamilton, WA

Average rainfall days in September - Hamilton, WA
  • Average rainfall days in September: 13.5 days

The month with the highest number of rainy days is March (22.1 days).
The month with the least rainy days is August (9.4 days).

Average snowfall in September
Hamilton, WA

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

The month with the highest snowfall is February (4.96").
The months with the least snowfall are May, June, July, August, September and October (0").

Average snowfall days in September
Hamilton, WA

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

The month with the highest number of snowfall days is February (4.3 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
Hamilton, WA

Average daylight in September / Average sunshine in September - Hamilton, WA
  • Average daylight in September: 12h and 4min

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 24min).

  • Average sunshine in September: 8h and 5min

The month with the most sunshine is August (Average sunshine: 10h and 18min).
The month with the least sunshine is December (Average sunshine: 3h and 30min).

Average sunshine days in September
Hamilton, WA

Average sunshine days in September - Hamilton, WA
  • Average sunshine days in September: 14.5 days

The month with the most sunshine days is August (19.2 days).
The month with the least sunshine days is March (7.3 days).

Average UV index in September
Hamilton, WA

Average UV index in September - Hamilton, 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, March, October, November and December (UV index 2).

Average cloud cover in September
Hamilton, WA

Average cloud cover in September - Hamilton, WA
  • Average cloud cover in September: 37

The month with the most cloud cover is December (Cloud cover 62).
The month with the least cloud cover is August (Cloud cover 28).

Average visibility in September
Hamilton, WA

Average visibility in September - Hamilton, WA
  • Average visibility in September: 5mi

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

Hamilton, Washington, USA

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