September weather forecast
Annapolis, MD

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The Chesapeake Bay at dusk, in Annapolis, Maryland, with a distant view of the US Naval Academy chapel dome
The Chesapeake Bay at dusk, in Annapolis, Maryland, with a distant view of the US Naval Academy chapel dome

Weather in September

September sees Annapolis transitioning from summer into fall. The cooling trend starts, presenting an ideal scenario for those seeking milder temperatures. Autumnal colors begin to paint the cityscape against a backdrop of reduced rainfall, now averaging at 0.63" (16mm). September in Annapolis is characterized by its mild climate, less humidity, and fewer crowds, making it a favorable month for visitors.

Temperature

The beginning of September subtly marks a decrease in the average high-temperature, transitioning from 83.3°F (28.5°C) in August to a still moderately hot 77°F (25°C). Annapolis experiences an average nighttime temperature of 64.6°F (18.1°C) in the month of September.

Humidity

In September, the average relative humidity is 75%.

Rainfall

In Annapolis, during September, the rain falls for 10.5 days and regularly aggregates up to 0.63" (16mm) of precipitation. Throughout the year, there are 120.4 rainfall days, and 10.47" (266mm) of precipitation is accumulated.

Snowfall

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

Ocean temperature

In Annapolis, Maryland, the average seawater temperature in September is 73.9°F (23.3°C).
Note: The cold tolerance of an individual, along with sunshine, wind, and the temperature of the environment, affects the enjoyment of swimming in 73.9°F (23.3°C) waters. (Olympic swimmers participate in waters ranging from 77°F (25°C) to 82.4°F (28°C).)

Daylight

The average length of the day in September in Annapolis is 12h and 26min.
On the first day of the month, sunrise is at 6:35 am and sunset at 7:36 pm. On the last day of September, sunrise is at 7:01 am and sunset at 6:49 pm EDT.

Sunshine

In Annapolis, the average sunshine in September is 9.2h.

UV index

The average daily maximum UV index in September is 5. A UV Index of 3 to 5 symbolizes a medium vulnerability from exposure to the Sun's UV rays for the ordinary person.
Note: In September, the maximum UV index of 5 translates into these guidelines:
Ensure safety - Imperative it is to shield skin and eyes from damage. To prevent harmful UV exposure, minimize direct contact with the Sun around midday. Sunglasses providing both UVA and UVB protection are non-negotiable on sunlit days. Warning! The Sun's UV rays intensify with reflections from sand and water.
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Frequently asked questions

What is the usual temperature for Annapolis in September?

Annapolis in September has an average high-temperature of 77°F (25°C) and an average low-temperature of 64.6°F (18.1°C). In August, the average heat index (a.k.a. 'real feel', 'feels like'), which calculates the temperature value influenced by the moisture in the air, is evaluated at 89.6°F (32°C).

What is the average humidity in September in Annapolis?

In Annapolis, the average relative humidity in September is 75%.

How many days does it rain in September in Annapolis?

In Annapolis, Maryland, in September, during 10.5 rainfall days, 0.63" (16mm) of precipitation is typically accumulated.

When it does not snow in Annapolis?

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

What is the ocean temperature in September in Annapolis?

In Annapolis, Maryland, in September, the average water temperature is 73.9°F (23.3°C). A person's cold intolerance, with sunshine, wind, and air temperature, are essential factors for enjoying swimming in 73.9°F (23.3°C) water.

How many hours of daylight does Annapolis have in September?

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

When are sunrise and sunset in September in Annapolis?

On the first day of September in Annapolis, sunrise is at 6:35 am and sunset at 7:36 pm. On the last day of the month, sunrise is at 7:01 am and sunset at 6:49 pm EDT.

How long on average sun shines in September in Annapolis?

In Annapolis, Maryland, the average sunshine duration in September is 9.2h.

What is the UV index intensity in September in Annapolis?

In Annapolis, the average daily maximum UV index in September is 5. A UV Index value of 3 to 5 symbolizes a medium health risk from 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
Annapolis, MD

Average temperature in September - Annapolis, MD
  • Average high temperature in September: 77°F

The warmest month (with the highest average high temperature) is July (84.7°F).
The month with the lowest average high temperature is January (40.3°F).

  • Average low temperature in September: 64.6°F

The month with the highest average low temperature is July (72°F).
The coldest month (with the lowest average low temperature) is January (29.8°F).

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Average pressure in September
Annapolis, MD

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

The month with the highest atmospheric pressure is November (30.13"Hg).
The month with the lowest atmospheric pressure is June (29.94"Hg).

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Average wind speed in September
Annapolis, MD

Average wind speed in September - Annapolis, MD
  • Average wind speed in September: 7.6mph

The windiest month (with the highest average wind speed) is January (10mph).
The calmest months (with the lowest average wind speed) are July and August (6.6mph).

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Average humidity in September
Annapolis, MD

Average humidity in September - Annapolis, MD
  • Average humidity in September: 75%

The month with the highest relative humidity is May (78%).
The months with the lowest relative humidity are January, March, April and November (72%).

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Average rainfall in September
Annapolis, MD

Average rainfall in September - Annapolis, MD
  • Average rainfall in September: 0.63"

The wettest month (with the highest rainfall) is August (1.69").
The driest month (with the least rainfall) is January (0.47").

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Average rainfall days in September
Annapolis, MD

Average rainfall days in September - Annapolis, MD
  • Average rainfall days in September: 10.5 days

The months with the highest number of rainy days are July and August (14.3 days).
The month with the least rainy days is November (5.3 days).

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Average snowfall in September
Annapolis, MD

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

The month with the highest snowfall is January (0.67").
The months with the least snowfall are April, May, June, July, August, September and October (0").

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Average snowfall days in September
Annapolis, MD

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

The month with the highest number of snowfall days is February (2.5 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).

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Average sea temperature in September
Annapolis, MD

Average sea temperature in September - Annapolis, MD
  • Average sea temperature in September: 73.9°F

The best month for swimming (with the highest average sea temperature) is August (77.8°F).
The coldest month (with the lowest average sea temperature) is February (45.1°F).

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

Average daylight in September / Average sunshine in September - Annapolis, 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 48min).
The month with the least sunshine is February (Average sunshine: 5h and 0min).

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Average sunshine days in September
Annapolis, MD

Average sunshine days in September - Annapolis, MD
  • Average sunshine days in September: 17.4 days

The month with the most sunshine days is November (23.4 days).
The month with the least sunshine days is August (13.8 days).

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Average UV index in September
Annapolis, MD

Average UV index in September - Annapolis, 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, February and December (UV index 2).

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Average cloud cover in September
Annapolis, MD

Average cloud cover in September - Annapolis, MD
  • Average cloud cover in September: 33

The months with the most cloud cover are February and March (Cloud cover 45).
The month with the least cloud cover is July (Cloud cover 28).

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Average visibility in September
Annapolis, MD

Average visibility in September - Annapolis, 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).

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Annapolis, Maryland, USA

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