September weather forecast
Frederick, MD

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A stone bridge over the calm Carroll Creek in the Carroll Creek Linear Park in Frederick, Maryland
A stone bridge over the calm Carroll Creek in the Carroll Creek Linear Park in Frederick, Maryland

Weather in September

September marks the beginning of the fall season in Frederick, Maryland, when the leaves start to change color and daylight begins to shorten. The temperatures start to withdraw from the summer swelter, settling at a comfortable average high of 76.3°F (24.6°C). Relaxing into the phase of autumn, September sees a significant drop in average temperature from the past month, promising slightly cooler days. The diminished daylight hours and heightened wind speeds resonate with the changing season. However, despite decreased rainfall, the remaining summer warmth sufficiently maintains the city's vibrance and charm.

Temperature

As September begins in Frederick, there is a minor decrease in the average high-temperature, softly falling from a warm 83.5°F (28.6°C) in August to a still moderately hot 76.3°F (24.6°C). During the September nights, an average temperature of 56.8°F (13.8°C) is observed.

Humidity

In September, the average relative humidity is 78%.

Rainfall

In Frederick, in September, it is raining for 13.4 days, with typically 2.05" (52mm) of accumulated precipitation. Throughout the year, there are 159.7 rainfall days, and 30.04" (763mm) of precipitation is accumulated.

Snowfall

June through October are months without snowfall in Frederick.

Daylight

In Frederick, the average length of the day in September is 12h and 26min.
On the first day of the month, sunrise is at 6:38 am and sunset at 7:40 pm. On the last day of September, in Frederick, sunrise is at 7:05 am and sunset at 6:53 pm EDT.

Sunshine

In Frederick, Maryland, the average sunshine in September is 8.8h.

UV index

In Frederick, the average daily maximum UV index in September is 4. A UV Index reading of 3 to 5 represents a medium vulnerability from unsafe exposure to UV radiation for the ordinary person.
Note: In September, a daily UV index of 4 turns into the following recommendations:
Exercise prevention - Precautions against solar damage are endorsed. The Sun's most intense and consequently most harmful UV radiation during midday hours should be decreased by minimizing exposure and seeking shade. To mitigate harm from sun exposure, pick sunglasses offering UVA and UVB defense.
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Frequently asked questions

What are the temperatures in Frederick in September?

The average high-temperature, in September, in Frederick, is 76.3°F (24.6°C), while the average low-temperature is 56.8°F (13.8°C). In August, the average heat index (a.k.a. 'real feel', 'felt air temperature'), which factors the actual air temperature with the relative humidity, is computed to be 91.4°F (33°C).

What is the average humidity in September in Frederick?

The average relative humidity in September in Frederick, Maryland, is 78%.

How many days does it rain in September in Frederick?

In September, the rain falls for 13.4 days. Throughout September, 2.05" (52mm) of precipitation is accumulated.

When it does not snow in Frederick?

In Frederick, snow does not fall in June through October.

How many hours of daylight does Frederick have in September?

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

When is the sunrise / sunset in September in Frederick?

On the first day of September, sunrise is at 6:38 am and sunset at 7:40 pm. On the last day of the month, sunrise is at 7:05 am and sunset at 6:53 pm EDT.

How long on average sun shines in September in Frederick?

In September, the average sunshine duration is 8.8h.

What is the UV index reading in September in Frederick?

The average daily maximum UV index in September in Frederick, Maryland, is 4. A UV Index of 3 to 5 symbolizes a moderate health threat 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
Frederick, MD

Average temperature in September - Frederick, MD
  • Average high temperature in September: 76.3°F

The warmest month (with the highest average high temperature) is July (85.6°F).
The month with the lowest average high temperature is January (37.6°F).

  • Average low temperature in September: 56.8°F

The month with the highest average low temperature is July (64.9°F).
The coldest month (with the lowest average low temperature) is January (23.7°F).

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Average pressure in September
Frederick, MD

Average pressure in September - Frederick, MD
  • Average pressure in September: 30.06"Hg

The month with the highest atmospheric pressure is November (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.95"Hg).

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Average wind speed in September
Frederick, MD

Average wind speed in September - Frederick, MD
  • Average wind speed in September: 5.3mph

The windiest month (with the highest average wind speed) is March (7.8mph).
The calmest months (with the lowest average wind speed) are July and August (4.7mph).

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Average humidity in September
Frederick, MD

Average humidity in September - Frederick, MD
  • Average humidity in September: 78%

The months with the highest relative humidity are May, October and December (79%).
The month with the lowest relative humidity is July (74%).

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Average rainfall in September
Frederick, MD

Average rainfall in September - Frederick, MD
  • Average rainfall in September: 2.05"

The wettest month (with the highest rainfall) is May (3.54").
The driest month (with the least rainfall) is January (1.85").

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Average rainfall days in September
Frederick, MD

Average rainfall days in September - Frederick, MD
  • Average rainfall days in September: 13.4 days

The month with the highest number of rainy days is May (18.6 days).
The month with the least rainy days is January (8.7 days).

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Average snowfall in September
Frederick, MD

Average snowfall in September - Frederick, MD
  • Average snowfall in September: 0"

The month with the highest snowfall is January (3.66").
The months with the least snowfall are June, July, August, September and October (0").

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Average snowfall days in September
Frederick, MD

Average snowfall days in September - Frederick, MD
  • Average snowfall days in September: 0 days

The months with the highest number of snowfall days are January and February (6.3 days).
The months with the least snowfall days are June, July, August, September and October (0 days).

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Average daylight in September /
Average sunshine in September
Frederick, MD

Average daylight in September / Average sunshine in September - Frederick, 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 24min).

  • Average sunshine in September: 8h and 5min

The month with the most sunshine is July (Average sunshine: 10h and 36min).
The months with the least sunshine are January and February (Average sunshine: 4h and 48min).

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Average sunshine days in September
Frederick, MD

Average sunshine days in September - Frederick, MD
  • Average sunshine days in September: 14.2 days

The month with the most sunshine days is November (18.9 days).
The month with the least sunshine days is May (11.1 days).

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Average UV index in September
Frederick, MD

Average UV index in September - Frederick, MD
  • Average UV index in September: 4

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, February, November and December (UV index 2).

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Average cloud cover in September
Frederick, MD

Average cloud cover in September - Frederick, MD
  • Average cloud cover in September: 38

The months with the most cloud cover are January, February and March (Cloud cover 48).
The month with the least cloud cover is July (Cloud cover 32).

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Average visibility in September
Frederick, MD

Average visibility in September - Frederick, MD
  • Average visibility in September: 5mi

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

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Frederick, Maryland, USA

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