September weather forecast
Mount Rainier, MD

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Weather in September

September's weather in Mount Rainier introduces the first hints of autumn, characterized by a decreasing number of daylight hours and lower temperatures. The obvious shift from the hot August months marks itself with a drop in the maximum temperature down to 78.1°F (25.6°C). As the end of the summer season is acknowledged, the cloud coverage starts to increase, creating a scenic view of the city. Looking forward to October, the weather becomes cooler, and the amount of rainfall shows a distinctive increase.

Temperature

With September's onset, the weather reveals a slight temperature decrease, transitioning from a warm 85.1°F (29.5°C) in August to a still moderately hot 78.1°F (25.6°C). Mount Rainier's temperature drops to an average low of 62.2°F (16.8°C) during the nights of September.

Humidity

The average relative humidity in September is 74%.

Rainfall

In Mount Rainier, in September, during 12.3 rainfall days, 2.09" (53mm) of precipitation is typically accumulated. Throughout the year, there are 157.9 rainfall days, and 31.14" (791mm) of precipitation is accumulated.

Snowfall

In Mount Rainier, snow does not fall in May through November.

Daylight

The average length of the day in September is 12h and 26min.
On the first day of September, sunrise is at 6:37 am and sunset at 7:37 pm. On the last day of the month, sunrise is at 7:03 am and sunset at 6:51 pm EDT.

Sunshine

In September, the average sunshine in Mount Rainier is 9.1h.

UV index

In Mount Rainier, the average daily maximum UV index in September is 5. A UV Index of 3 to 5 symbolizes a medium health hazard from exposure to the Sun's UV rays for average individuals.
Note: In September, an average UV index of 5 transforms into the following instructions:
Undertake protective steps - Recommendations to avoid sunburn are issued. Avoiding direct sun during mid-day hours can prevent harmful UV radiation exposure. Opt for tightly woven and loose clothing to enhance protection from the Sun.

Frequently asked questions

What is the usual temperature for Mount Rainier in September?

The average high-temperature, in September, in Mount Rainier, is 78.1°F (25.6°C), while the average low-temperature is 62.2°F (16.8°C). In August, the average heat index (a.k.a. 'felt air temperature', 'feels like'), which combines relative humidity and air temperature, is estimated at 93.2°F (34°C).

What is the average humidity in September in Mount Rainier?

In September, the average relative humidity is 74%.

How many days does it rain in September?

In Mount Rainier, in September, during 12.3 rainfall days, 2.09" (53mm) of precipitation is typically accumulated.

When it does not snow?

May through November are months without snowfall.

How many hours of daylight does Mount Rainier have in September?

In September, the average day length in Mount Rainier, Maryland, is 12h and 26min.

When are sunrise and sunset in September?

On the first day of September, sunrise is at 6:37 am and sunset at 7:37 pm. On the last day of the month, sunrise is at 7:03 am and sunset at 6:51 pm EDT.

How long on average sun shines in September?

In Mount Rainier, the average sunshine duration in September is 9.1h.

What is the UV index intensity in September?

In Mount Rainier, the average daily maximum UV index in September is 5. A UV Index reading of 3 to 5 represents a medium hazard to health from unsafe exposure to Sun's UV rays.
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
Mount Rainier, MD

Average temperature in September - Mount Rainier, MD
  • Average high temperature in September: 78.1°F

The warmest month (with the highest average high temperature) is July (87.4°F).
The month with the lowest average high temperature is January (39.9°F).

  • Average low temperature in September: 62.2°F

The month with the highest average low temperature is July (70°F).
The coldest month (with the lowest average low temperature) is January (27.7°F).

Average pressure in September
Mount Rainier, MD

Average pressure in September - Mount Rainier, MD
  • Average pressure in September: 30.05"Hg

The month with the highest atmospheric pressure is November (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.94"Hg).

Average wind speed in September
Mount Rainier, MD

Average wind speed in September - Mount Rainier, MD
  • Average wind speed in September: 6.1mph

The windiest month (with the highest average wind speed) is March (8.3mph).
The calmest month (with the lowest average wind speed) is August (5.3mph).

Average humidity in September
Mount Rainier, MD

Average humidity in September - Mount Rainier, MD
  • Average humidity in September: 74%

The months with the highest relative humidity are May, October and December (76%).
The months with the lowest relative humidity are April and July (71%).

Average rainfall in September
Mount Rainier, MD

Average rainfall in September - Mount Rainier, MD
  • Average rainfall in September: 2.09"

The wettest month (with the highest rainfall) is August (3.58").
The driest month (with the least rainfall) is January (2.01").

Average rainfall days in September
Mount Rainier, MD

Average rainfall days in September - Mount Rainier, MD
  • Average rainfall days in September: 12.3 days

The month with the highest number of rainy days is May (17.9 days).
The month with the least rainy days is November (9 days).

Average snowfall in September
Mount Rainier, MD

Average snowfall in September - Mount Rainier, MD
  • Average snowfall in September: 0"

The month with the highest snowfall is January (2.6").
The months with the least snowfall are May, June, July, August, September, October and November (0").

Average snowfall days in September
Mount Rainier, MD

Average snowfall days in September - Mount Rainier, MD
  • Average snowfall days in September: 0 days

The month with the highest number of snowfall days is January (4.1 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
Mount Rainier, MD

Average daylight in September / Average sunshine in September - Mount Rainier, MD
  • Average daylight in September: 12h and 2min

The month with the longest days is June (Average daylight: 14h and 54min).
The month with the shortest days is December (Average daylight: 9h and 30min).

  • Average sunshine in September: 9h and 1min

The month with the most sunshine is July (Average sunshine: 10h and 54min).
The month with the least sunshine is February (Average sunshine: 5h and 0min).

Average sunshine days in September
Mount Rainier, MD

Average sunshine days in September - Mount Rainier, MD
  • Average sunshine days in September: 15.6 days

The month with the most sunshine days is November (19.1 days).
The month with the least sunshine days is May (11.8 days).

Average UV index in September
Mount Rainier, MD

Average UV index in September - Mount Rainier, MD
  • Average UV index in September: 5

The months with the highest UV index are May, June, July and August (UV index 6).
The months with the lowest UV index are January and December (UV index 2).

Average cloud cover in September
Mount Rainier, MD

Average cloud cover in September - Mount Rainier, MD
  • Average cloud cover in September: 36

The month with the most cloud cover is March (Cloud cover 46).
The month with the least cloud cover is July (Cloud cover 29).

Average visibility in September
Mount Rainier, MD

Average visibility in September - Mount Rainier, MD
  • Average visibility in September: 6mi

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

Mount Rainier, Maryland, USA

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