September weather forecastGrand Portage, MN
September
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.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
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: 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: 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: 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: 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: 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: 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: 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: 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: 12h and 36min
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 36min
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: 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: 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: 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: 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).
