St. Lawrence River Climate and Average Weather
Climate of St. Lawrence River: average temperatures, rainfall and seasons month by month.
Climate in St. Lawrence River month by month
Average high, average low and total rainfall, based on three years of reanalysis data.
| Month | Avg high | Avg low | Rainfall | Rating |
|---|---|---|---|---|
| January | 21° | 5° | 2,7 in | ★★☆☆☆ |
| February | 24° | 4° | 2,0 in | ★★☆☆☆ |
| March | 34° | 16° | 4,1 in | ★★☆☆☆ |
| April | 49° | 30° | 4,9 in | ★★☆☆☆ |
| May | 62° | 43° | 5,0 in | ★★★☆☆ |
| June | 73° | 54° | 6,9 in | ★★★☆☆ |
| July | 78° | 60° | 5,1 in | ★★★★☆ |
| August | 75° | 57° | 6,5 in | ★★★☆☆ |
| September | 68° | 50° | 2,4 in | ★★★★☆ |
| October | 55° | 40° | 2,8 in | ★★★☆☆ |
| November | 38° | 27° | 3,5 in | ★★☆☆☆ |
| December | 26° | 11° | 3,8 in | ★☆☆☆☆ |
Climate type: Subarctic. Source: Open-Meteo archive (ERA5).
Recent extremes in St. Lawrence River
Highest and lowest readings observed in the last 3 years of reanalysis data - not all-time records.
How St. Lawrence River compares with nearby places
Annual averages, and the difference against St. Lawrence River.
| Place | Distance | Avg temp | vs here | Annual rain |
|---|---|---|---|---|
| Quebec City | 0 mi | 42°F | about the same | 50 in |
| Baxter State Park | 126 mi | 28°F | 46°F cooler | 53 in |
| Montreal | 145 mi | 46°F | +36°F warmer | 42 in |
| Montreal-Trudeau International Airport | 153 mi | 47°F | +37°F warmer | 43 in |
| Mont-Tremblant National Park | 159 mi | 40°F | 34°F cooler | 51 in |
Best time to visit St. Lawrence River
Go in July and September. These months score highest on comfortable temperatures, low rainfall and useful daylight.
Hardest months: January, March and December - expect the least comfortable mix of heat, cold or rain.
What this means for St. Lawrence River
Today is much colder than average for October. The forecast high of 40°F is 15.1°F below the 55°F typical for this month.
Rain is very unlikely today - plans do not need a backup.
Overnight lows near 23°F mean ice is possible on bridges before dawn.
Northern Hemisphere, so peak summer falls in June to August.
The gap between the warmest and coldest month averages 88°F.
What to pack, what to skip
- A warm mid-layer and gloves for early mornings and evenings
- Insulated outer layer, hat and boots with grip for ice
- A packable rain shell - 2 of the next 7 days carry a real chance of rain
- Avoid high-elevation trails without traction devices - frozen surfaces persist in shade all day.
- If your dates are flexible, avoid January, March and December - historically the least comfortable months here.
Summary
St. Lawrence River is a river in Quebec. St. Lawrence River is a river known as the Great Lakes outlet to the Atlantic.
Right now it is 23°F (-5°C) in St. Lawrence River with overcast. It feels like 17°F. Today runs from 23°F to 40°F. Chance of precipitation is 0%. Sightseeing conditions score 7.3/10 - good conditions.
The best time to visit St. Lawrence River is July and September. The climate is subarctic. January, March and December tend to be the least comfortable months. July is the warmest month with average highs near 78°F, while February is the coldest with lows near 4°F.
The closest major airport is Montreal-Trudeau International Airport (YUL), about 153 mi away. Nearby highlights include Baxter State Park, Mont-Tremblant National Park, Mount Washington and Franconia Notch State Park.
In plain terms. Today is much colder than average for October. The forecast high of 40°F is 15.1°F below the 55°F typical for this month. The best window to be outside is roughly 8 AM to 11 AM, when temperature, rain chance and wind line up best. driving is the strongest bet in St. Lawrence River today at 9.7/10. Overnight lows near 23°F mean ice is possible on bridges before dawn.
Compiled from this page's own data: atlas facts plus live Open-Meteo readings.
Quick facts about St. Lawrence River
| Type | River |
|---|---|
| State | Quebec |
| Country | Canada |
| Continent | North America |
| Coordinates | 46°48′50″N 71°12′28.8″W (46.8139, -71.208) |
| Length | 744 mi |
| Known for | the Great Lakes outlet to the Atlantic |
| Local time | 1:01 PM (UTC-04:00) |
| Best months | July and September |
| Climate | Subarctic |
Weather map for St. Lawrence River
Animated model layers. Pick a layer to load it.
Animated layers by Windy. For pin-level detail and nearby places, see the interactive map below.
Explore St. Lawrence River
Every topic we hold for this place, and the same topic for the places around it.
Climate for related places
Frequently asked questions
Where is St. Lawrence River?
St. Lawrence River is a river in Quebec. Its coordinates are 46.8139, -71.208. It lies in North America.
What is the weather like in St. Lawrence River right now?
It is currently 23°F (-5°C) with overcast. Humidity is 90% and wind is 3 mph.
When is the best time to visit St. Lawrence River?
July and September offer the most comfortable conditions in St. Lawrence River, which has a subarctic climate. January, March and December are usually the hardest months for outdoor plans.
What time zone is St. Lawrence River in?
St. Lawrence River observes America/Toronto (UTC-04:00). The local time is 1:01 PM.
What is the nearest airport to St. Lawrence River?
The closest airports are Montreal-Trudeau International Airport (YUL), 153 mi away and Boston Logan International Airport (BOS), 308 mi away.
What are the top things to do in St. Lawrence River?
Popular options include Baxter State Park, Mont-Tremblant National Park, Mount Washington, Franconia Notch State Park and Acadia National Park.
Related articles
Data sources and methodology
| Place data | USPOTUS Atlas dataset (rivers) - coordinates, hierarchy and facts. |
|---|---|
| Forecast and observations | Open-Meteo (ECMWF and national models). |
| Air quality and pollen | Copernicus CAMS via Open-Meteo. US AQI scale. |
| Climate averages | ERA5 reanalysis via the Open-Meteo archive, aggregated over 3 years. |
| Method | Scores, comparisons and advice on this page are computed from the inputs above. Distances are straight-line. Nothing is estimated where data is missing - the block is simply not shown. |
Last updated October 28, 2026 at 1:01 PM local time. Live blocks refresh every 15 minutes; climate averages monthly.
