September weather forecast and climate
Duluth, MN

What is the temperature in September in Duluth?

In Duluth, in September, the average high-temperature is 64.9°F (18.3°C), and the average low-temperature is 46°F (7.8°C).

How much does it rain in Duluth in September?

In Duluth, during September, the rain falls for 12.3 days and regularly aggregates up to 4.1" (104.4mm) of precipitation.

When does it start to snow in Duluth?

September is the first month it typically snows in Duluth, Minnesota. Throughout September, in the average 0.1 snowfall days, it receives 0.1" (2.5mm) of snow.

What is the water temperature in September in Duluth?

The average seawater temperature, in September, in Duluth, is 57.2°F (14°C). Swimming in 57.2°F (14°C) is considered dangerous. Unprotected immersion in temperatures below 50°F (10°C) causes quickly maximum intensity cold shock with hyperventilation.
Average temperature in September - Duluth, MN
  • Average high temperature in September: 65°F

The warmest month (with the highest average high temperature) is July (76.3°F).
The month with the lowest average high temperature is January (18.9°F).

  • Average low temperature in September: 46.1°F

The month with the highest average low temperature is July (55.4°F).
The coldest month (with the lowest average low temperature) is January (1.5°F).

Average humidity in September - Duluth, MN
  • Average humidity in September: 75.7%

The month with the highest relative humidity is December (76.3%).
The month with the lowest relative humidity is May (62.7%).

Average rainfall in September - Duluth, MN
  • Average rainfall in September: 4.1"

The wettest month (with the highest rainfall) is June (4.2").
The driest month (with the lowest rainfall) is February (0.8").

Average rainfall days in September - Duluth, MN
  • Average rainfall days in September: 12.3 days

The month with the highest number of rainy days is June (12.6 days).
The month with the lowest number of rainy days is February (8.5 days).

Average snowfall in September - Duluth, MN
  • Average snowfall in September: 0.1"

The month with the highest snowfall is January (19.4").
Months with the lowest snowfall are June, July and August (0").

Average snowfall days in September - Duluth, MN
  • Average snowfall days in September: 0.1 days

The month with the highest number of snowfall days is January (12.9 days).
Months with the lowest number of snowfall days are June, July and August (0 days).

Average sea temperature in September - Duluth, MN
  • Average sea temperature in September: 57°F

The best month for swimming (with the highest average sea temperature) is August (61°F).
Coldest months (with the lowest average sea temperature) are January, February, March and April (36°F).

Average daylight in September / Average sunshine in September - Duluth, MN
  • Average daylight in September: 12.5h

The month with the longest days is June (Average daylight: 15.8h).
The month with shortest days is December (Average daylight: 8.6h).

  • Average sunshine in September: 6.5h

The month with most sunshine is July (Average sunshine: 9.9h).
Months with least sunshine are November and December (Average sunshine: 3.3).

Average UV index in September - Duluth, MN
  • Average UV index in September: 5

Months with the highest UV index are June and July (UV index 8).
Months with the lowest UV index are January, November and December (UV index 1).

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