September weather forecast
Grand Marais, MI

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Weather in September

September marks the transition from summer to fall in Grand Marais. The change is noted in the decreasing daylight hours and sunshine duration, as well as the falling sea temperature. The month experiences a moderate increase in cloud coverage, leading to somewhat reduced visibility. The month's numbers reveal a downward temperature shift from 51.6°F (10.9°C) to 65.1°F (18.4°C), with no occurrence of snowfall. The overall pleasant weather coupled with vibrant fall colors in the surrounding landscape, make it even more inviting for outdoor enthusiasts.

Temperature

The transition to September in Grand Marais results in a modest reduction in average high-temperature, moving from an agreeable 71.8°F (22.1°C) in August to an enjoyable 65.1°F (18.4°C). Throughout the month of September, Grand Marais reports a steady low-temperature average of 51.6°F (10.9°C).

Humidity

In Grand Marais, the average relative humidity in September is 80%.

Rainfall

In Grand Marais, in September, during 12.7 rainfall days, 1.93" (49mm) of precipitation is typically accumulated. In Grand Marais, during the entire year, the rain falls for 123.2 days and collects up to 22.17" (563mm) of precipitation.

Snowfall

June through September are months without snowfall in Grand Marais, Michigan.

Ocean temperature

In Grand Marais, in September, the average water temperature is 57.2°F (14°C).
Note: While a brief time in 57.2°F (14°C) at 55.4°F (13°C) is already bracing, plunging below 50°F (10°C) can severely affect breathing and introduce a cold shock, relying on your physical state.

Daylight

In September, the average length of the day is 12h and 32min.
On the first day of the month, sunrise is at 7:04 am and sunset at 8:22 pm. On the last day of September, in Grand Marais, sunrise is at 7:42 am and sunset at 7:25 pm EDT.

Sunshine

In Grand Marais, the average sunshine in September is 7.5h.

UV index

In September, the average daily maximum UV index is 3. A UV Index estimate of 3 to 5 represents a medium health hazard from exposure to the Sun's UV radiation for the ordinary person.
Note: An average maximum UV index of 3 in September leads to these recommendations:
Adopt protective measures - It is advised to guard against sun damage. Considering the harmful UV rays from the Sun during midday, it's essential to reduce exposure. A wide-brim hat offers excellent sun protection for the eyes, ears, face, and neck. Sunglasses with UVA and UVB protection significantly reduce eye damage from sun exposure.
Updated: Feb 12, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What are the temperatures in Grand Marais in September?

In Grand Marais, 65.1°F (18.4°C) is the average high-temperature and 51.6°F (10.9°C) is the average low-temperature during September.

What is the average humidity in September in Grand Marais?

In September, the average relative humidity is 80%.

How many days does it rain in September in Grand Marais?

In Grand Marais, during September, the rain falls for 12.7 days and regularly aggregates up to 1.93" (49mm) of precipitation.

When it does not snow in Grand Marais?

June through September are months without snowfall in Grand Marais.

Does it snow in Grand Marais in September?

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

What is the ocean temperature in September in Grand Marais?

In Grand Marais, the average seawater temperature in September 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.

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

The average day length in September in Grand Marais is 12h and 32min.

When is the sunrise / sunset in September in Grand Marais?

In September, on the first day of the month, sunrise is at 7:04 am and sunset at 8:22 pm. On the last day of the month, in Grand Marais, Michigan, sunrise is at 7:42 am and sunset at 7:25 pm EDT.

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

In September, the average sunshine duration in Grand Marais is 7.5h.

How high is the UV index in September in Grand Marais?

The average daily maximum UV index in September in Grand Marais, Michigan, is 3. A UV Index reading of 3 to 5 represents a medium hazard to health 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
Grand Marais, MI

Average temperature in September - Grand Marais, MI
  • Average high temperature in September: 65.1°F

The warmest month (with the highest average high temperature) is July (72.1°F).
The month with the lowest average high temperature is January (22.8°F).

  • Average low temperature in September: 51.6°F

The month with the highest average low temperature is August (56.8°F).
The coldest month (with the lowest average low temperature) is February (13.6°F).

Average pressure in September
Grand Marais, MI

Average pressure in September - Grand Marais, MI
  • Average pressure in September: 30.01"Hg

The month with the highest atmospheric pressure is March (30.09"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).

Average wind speed in September
Grand Marais, MI

Average wind speed in September - Grand Marais, MI
  • Average wind speed in September: 8.3mph

The windiest month (with the highest average wind speed) is November (10.1mph).
The calmest month (with the lowest average wind speed) is July (7.1mph).

Average humidity in September
Grand Marais, MI

Average humidity in September - Grand Marais, MI
  • Average humidity in September: 80%

The months with the highest relative humidity are January and February (91%).
The month with the lowest relative humidity is May (73%).

Average rainfall in September
Grand Marais, MI

Average rainfall in September - Grand Marais, MI
  • Average rainfall in September: 1.93"

The wettest month (with the highest rainfall) is October (2.8").
The driest month (with the least rainfall) is March (1.5").

Average rainfall days in September
Grand Marais, MI

Average rainfall days in September - Grand Marais, MI
  • Average rainfall days in September: 12.7 days

The month with the highest number of rainy days is October (15.3 days).
The month with the least rainy days is February (3.1 days).

Average snowfall in September
Grand Marais, MI

Average snowfall in September - Grand Marais, MI
  • Average snowfall in September: 0"

The month with the highest snowfall is January (10.08").
The months with the least snowfall are June, July, August and September (0").

Average snowfall days in September
Grand Marais, MI

Average snowfall days in September - Grand Marais, MI
  • Average snowfall days in September: 0 days

The month with the highest number of snowfall days is January (24.8 days).
The months with the least snowfall days are June, July, August and September (0 days).

Average sea temperature in September
Grand Marais, MI

Average sea temperature in September - Grand Marais, MI
  • Average sea temperature in September: 57°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 March and April (36°F).

Average daylight in September /
Average sunshine in September
Grand Marais, MI

Average daylight in September / Average sunshine in September - Grand Marais, MI
  • Average daylight in September: 12h and 3min

The month with the longest days is June (Average daylight: 15h and 48min).
The month with the shortest days is December (Average daylight: 8h and 36min).

  • Average sunshine in September: 7h and 3min

The month with the most sunshine is July (Average sunshine: 9h and 54min).
The month with the least sunshine is January (Average sunshine: 1h and 36min).

Average sunshine days in September
Grand Marais, MI

Average sunshine days in September - Grand Marais, MI
  • Average sunshine days in September: 15.4 days

The month with the most sunshine days is June (16.3 days).
The month with the least sunshine days is January (5.8 days).

Average UV index in September
Grand Marais, MI

Average UV index in September - Grand Marais, MI
  • Average UV index in September: 3

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

Average cloud cover in September
Grand Marais, MI

Average cloud cover in September - Grand Marais, MI
  • Average cloud cover in September: 38

The month with the most cloud cover is January (Cloud cover 83).
The month with the least cloud cover is July (Cloud cover 34).

Average visibility in September
Grand Marais, MI

Average visibility in September - Grand Marais, MI
  • Average visibility in September: 6mi

The months with the highest visibility are April, May, June, July, August, September, October and November (6mi).
The months with the lowest visibility are January and February (4mi).

Grand Marais, Michigan, USA

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