Annapolis
Maryland, USA
Long-term weather forecast
Long-term weather forecast

September weather forecast and climate
Annapolis, MD

A view of Chesapeake Bay at dusk, in Annapolis, Maryland, with a distant view of the US Naval Academy chapel dome
A view of Chesapeake Bay at dusk, in Annapolis, Maryland, with a distant view of the US Naval Academy chapel dome
The first month of the autumn, September, is still a warm month in Annapolis, Maryland, with average temperature varying between 77°F (25°C) and 64.6°F (18.1°C).

Temperature

In Annapolis, the average high-temperature marginally drops, from a moderately hot 83.3°F (28.5°C) in August, to a still warm 77°F (25°C). In Annapolis, the average low-temperature is 64.6°F (18.1°C).

Humidity

The average relative humidity in September is 75%.

Rainfall

In Annapolis, in September, during 10.5 rainfall days, 0.63" (16mm) of precipitation is typically accumulated. In Annapolis, during the entire year, the rain falls for 120.4 days and collects up to 10.47" (266mm) of precipitation.

Snowfall

April through October are months without snowfall in Annapolis.

Ocean temperature

In September, the average ocean temperature in Annapolis is 73.9°F (23.3°C).
Note: 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. (FYI: The Olympic swimming competition requires a water temperature between 77°F (25°C) and 82.4°F (28°C).)

Daylight

In Annapolis, Maryland, the average length of the day in September is 12.4h.

Sunshine

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

UV index

In Annapolis, the average daily maximum UV index in September is 5. A UV Index value of 3 to 5 symbolizes a moderate health risk from unsafe exposure to the UV radiation for the average person.
Note: The daily maximum UV index of 5 in September interpret into the following advice:
Take precautions. Light skin individuals may get burned in less than 30 minutes. The Sun's most intense and consequently most harmful UV radiation during midday hours should be decreased by minimizing exposure and seeking shade. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects. Beware! The reflection of water and sand dramatically increases exposure to the UV rays.

What is the temperature in September in Annapolis?

The average high-temperature, in September, is 77°F (25°C), while the average low-temperature is 64.6°F (18.1°C).

What is the average humidity in September in Annapolis?

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

How many days does it rain in September in Annapolis?

In Annapolis, in September, it is raining for 10.5 days, with typically 0.63" (16mm) of accumulated precipitation.

When it does not snow in Annapolis?

April through October are months without snowfall.

What is the water temperature in September in Annapolis?

In Annapolis, Maryland, in September, the average water temperature is 73.9°F (23.3°C). Depending on a person's sensitivity to cold, with regards to sunshine, wind, and air temperature, a quick swim in 73.9°F (23.3°C) water may be enjoyable.

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

In Annapolis, the average length of the day in September is 12.4h.

How long on average sun shines in September in Annapolis?

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

How high is the UV index in September in Annapolis?

The average daily maximum UV index in September in Annapolis, Maryland, is 5. A UV Index estimate of 3 to 5 represents a moderate health threat from the exposure to the Sun's UV radiation.
Average temperature in September - Annapolis, MD
  • Average high temperature in September: 25°C

The warmest month (with the highest average high temperature) is July (29.3°C).
The month with the lowest average high temperature is January (4.6°C).

  • Average low temperature in September: 18.1°C

The month with the highest average low temperature is July (22.2°C).
The coldest month (with the lowest average low temperature) is January (-1.2°C).

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

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

Average rainfall in September - Annapolis, MD
  • Average rainfall in September: 16mm

The wettest month (with the highest rainfall) is August (43mm).
The driest month (with the lowest rainfall) is January (12mm).

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

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

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

The month with the highest snowfall is January (17mm).
Months with the lowest snowfall are April, May, June, July, August, September and October (0mm).

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).
Months with the lowest number of snowfall days are May, June, July, August, September and October (0 days).

Average sea temperature in September - Annapolis, MD
  • Average sea temperature in September: 23.3°C

The best month for swimming (with the highest average sea temperature) is August (25.4°C).
The coldest month (with the lowest average sea temperature) is February (7.3°C).

Average daylight in September / Average sunshine in September - Annapolis, MD
  • Average daylight in September: 12.4h

The month with the longest days is June (Average daylight: 14.9h).
The month with shortest days is December (Average daylight: 9.5h).

  • Average sunshine in September: 9.2h

The month with most sunshine is July (Average sunshine: 10.8h).
The month with least sunshine is February (Average sunshine: 5h).

Average UV index in September - Annapolis, MD
  • Average UV index in September: 5

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