September weather forecast
Grand Portage, MN

Share

Weather in September

September in Grand Portage symbolizes the onset of autumn, bringing a noticeable decline in temperature. Extremes fade, making way for a steady, comfortable weather pattern. The daylight hours start shrinking and residents experience a cumulative increase in cloud cover. Changes in wind patterns are minimal, contributing to the tranquility of fall weather. Gradual changes in the environment bring forward a palette of autumn.

Temperature

Grand Portage's progression into September involves a gentle drop in the average high-temperature, from a pleasant 70°F (21.1°C) in August to a comfortable 61.7°F (16.5°C). During the month of September, Grand Portage's nighttime temperature lowers to an average of 48°F (8.9°C).

Humidity

The average relative humidity in September in Grand Portage is 79%.

Rainfall

In September, in Grand Portage, the rain falls for 10.7 days. Throughout September, 1.73" (44mm) of precipitation is accumulated. In Grand Portage, during the entire year, the rain falls for 115 days and collects up to 18.19" (462mm) of precipitation.

Snowfall

In Grand Portage, snow does not fall in June through September.

Ocean temperature

In Grand Portage, Minnesota, the average seawater temperature in September is 55.4°F (13°C).
Note: At temperatures below 50°F (10°C), swimming in a suitably protected swimsuit is feasible; otherwise, cold shock and loss of breathing control are imminent. Even a short swim, without thermal protection, at temperatures around 55.4°F (13°C) is not comfortable.

Daylight

In September, the average length of the day in Grand Portage is 12h and 34min.
On the first day of the month, sunrise is at 6:17 am and sunset at 7:39 pm. On the last day of September, sunrise is at 6:57 am and sunset at 6:39 pm CDT.

Sunshine

In Grand Portage, the average sunshine in September is 7.6h.

UV index

In Grand Portage, the average daily maximum UV index in September is 3. A UV Index estimate of 3 to 5 represents a moderate threat to health from exposure to the Sun's UV radiation for ordinary individuals.
Note: In September, the maximum UV index of 3 suggests this advice:
Guard yourself - Avoiding sunburn is suggested. Sun exposure should be minimized, especially during midday, to avoid harmful UV radiation. Sun-related eye harm can be minimized with proper sunglasses offering UVA and UVB coverage.
Updated: Feb 12, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What is the average September temperature in Grand Portage?

An average high-temperature, in September, in Grand Portage, is 61.7°F (16.5°C) and the average low-temperature is 48°F (8.9°C).

What is the average humidity in September in Grand Portage?

In September, the average relative humidity in Grand Portage, Minnesota, is 79%.

How much does it rain in Grand Portage in September?

In September, the rain falls for 10.7 days. Throughout September, 1.73" (44mm) of precipitation is accumulated.

When it does not snow in Grand Portage?

In Grand Portage, Minnesota, snow does not fall in June through September.

Does it snow in Grand Portage in September?

In Grand Portage, Minnesota, in September, it doesn't snow. In October, it regularly snows.

How cold is the water in September in Grand Portage?

In September, the average ocean temperature in Grand Portage, Minnesota, is 55.4°F (13°C). Swimming in 55.4°F (13°C) is considered life-threatening. Even a few minutes in 55.4°F (13°C) water is uncomfortable, and swimming below 50°F (10°C) may cause total loss of breathing control and cold shock, depending on a person's physique.

What is the average length of the day in September in Grand Portage?

In Grand Portage, Minnesota, the average day length in September is 12h and 34min.

When are sunrise and sunset in September in Grand Portage?

On the first day of September in Grand Portage, sunrise is at 6:17 am and sunset at 7:39 pm. On the last day of the month, sunrise is at 6:57 am and sunset at 6:39 pm CDT.

How long on average sun shines in September in Grand Portage?

In Grand Portage, the average sunshine duration in September is 7.6h.

What is the UV index intensity in September in Grand Portage?

In Grand Portage, the average daily maximum UV index in September is 3. A UV Index value of 3 to 5 symbolizes a moderate health threat 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
Grand Portage, MN

Average temperature in September - Grand Portage, MN
  • Average high temperature in September: 61.7°F

The warmest months (with the highest average high temperature) are July and August (70°F).
The month with the lowest average high temperature is January (16.2°F).

  • Average low temperature in September: 48°F

The month with the highest average low temperature is August (54.3°F).
The coldest month (with the lowest average low temperature) is January (3.7°F).

Average pressure in September
Grand Portage, MN

Average pressure in September - Grand Portage, MN
  • Average pressure in September: 29.98"Hg

The month with the highest atmospheric pressure is March (30.09"Hg).
The month with the lowest atmospheric pressure is June (29.9"Hg).

Average wind speed in September
Grand Portage, MN

Average wind speed in September - Grand Portage, MN
  • Average wind speed in September: 7.3mph

The windiest month (with the highest average wind speed) is December (9.2mph).
The calmest month (with the lowest average wind speed) is June (6.2mph).

Average humidity in September
Grand Portage, MN

Average humidity in September - Grand Portage, MN
  • Average humidity in September: 79%

The months with the highest relative humidity are January and February (90%).
The month with the lowest relative humidity is May (70%).

Average rainfall in September
Grand Portage, MN

Average rainfall in September - Grand Portage, MN
  • Average rainfall in September: 1.73"

The wettest months (with the highest rainfall) are May and October (1.77").
The driest months (with the least rainfall) are January and February (1.06").

Average rainfall days in September
Grand Portage, MN

Average rainfall days in September - Grand Portage, MN
  • Average rainfall days in September: 10.7 days

The month with the highest number of rainy days is July (12.9 days).
The month with the least rainy days is February (4.2 days).

Average snowfall in September
Grand Portage, MN

Average snowfall in September - Grand Portage, MN
  • Average snowfall in September: 0"

The month with the highest snowfall is January (7.76").
The months with the least snowfall are June, July, August and September (0").

Average snowfall days in September
Grand Portage, MN

Average snowfall days in September - Grand Portage, MN
  • Average snowfall days in September: 0 days

The month with the highest number of snowfall days is January (21.6 days).
The months with the least snowfall days are June, July, August and September (0 days).

Average sea temperature in September
Grand Portage, MN

Average sea temperature in September - Grand Portage, MN
  • Average sea temperature in September: 55°F

The best month for swimming (with the highest average sea temperature) is August (59°F).
The coldest months (with the lowest average sea temperature) are January, February, March and April (36°F).

Average daylight in September /
Average sunshine in September
Grand Portage, MN

Average daylight in September / Average sunshine in September - Grand Portage, MN
  • Average daylight in September: 12h and 4min

The month with the longest days is June (Average daylight: 16h and 0min).
The month with the shortest days is December (Average daylight: 8h and 30min).

  • Average sunshine in September: 7h and 4min

The month with the most sunshine is June (Average sunshine: 10h and 24min).
The month with the least sunshine is January (Average sunshine: 3h and 0min).

Average sunshine days in September
Grand Portage, MN

Average sunshine days in September - Grand Portage, MN
  • Average sunshine days in September: 18.1 days

The month with the most sunshine days is September (18.1 days).
The month with the least sunshine days is March (9.8 days).

Average UV index in September
Grand Portage, MN

Average UV index in September - Grand Portage, MN
  • Average UV index in September: 3

The month with the highest UV index is July (UV index 5).
The months with the lowest UV index are January, February, March, November and December (UV index 1).

Average cloud cover in September
Grand Portage, MN

Average cloud cover in September - Grand Portage, MN
  • Average cloud cover in September: 39

The month with the most cloud cover is January (Cloud cover 70).
The month with the least cloud cover is July (Cloud cover 33).

Average visibility in September
Grand Portage, MN

Average visibility in September - Grand Portage, MN
  • Average visibility in September: 6mi

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

Grand Portage, Minnesota, USA

Weather forecast for your location

1. Click Locate me button
2. Allow the app to use your location