This report describes the typical weather at the Montréal-Pierre Elliott Trudeau International Airport (Montreal, Quebec, Canada) weather station over the course of an average year. It is based on the historical records from 1977 to 2012. Earlier records are either unavailable or unreliable.
Montreal, Quebec has a humid continental climate with warm summers and no dry season. The area within 25 mi of this station is covered by croplands (38%), grasslands (25%), forests (21%), lakes and rivers (11%), and built-up areas (6%).
Over the course of a year, the temperature typically varies from 7°F to 79°F and is rarely below -11°F or above 86°F.
The warm season lasts from May 22 to September 17 with an average daily high temperature above 68°F. The hottest day of the year is July 25, with an average high of 79°F and low of 63°F.
The cold season lasts from December 4 to March 11 with an average daily high temperature below 33°F. The coldest day of the year is January 19, with an average low of 7°F and high of 22°F.
The length of the day varies significantly over the course of the year. The shortest day is December 21 with 8:43 hours of daylight; the longest day is June 20 with 15:40 hours of daylight.
The earliest sunrise is at 5:05am on June 12 and the latest sunset is at 8:48pm on June 28. The latest sunrise is at 7:38am on November 3 and the earliest sunset is at 4:11pm on December 10.
Daylight savings time (DST) is observed in this location during 2012, starting in the spring on March 11 and ending in the fall on November 4.
The median cloud cover ranges from 73% (partly cloudy) to 96% (overcast). The sky is cloudiest on December 20 and clearest on August 13. The clearer part of the year begins around May 25. The cloudier part of the year begins around October 6.
On August 13, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 47% of the time, and overcast or mostly cloudy 51% of the time.
On December 20, the cloudiest day of the year, the sky is overcast, mostly cloudy, or partly cloudy 75% of the time, and clear or mostly clear 23% of the time.
The probability that precipitation will be observed at this location varies throughout the year. Precipitation is most likely around December 24, occurring in 76% of days. Precipitation is least likely around August 22, occurring in 49% of days.
Over the entire year, the most common forms of precipitation are light rain, light snow, and moderate rain.
Light rain is the most severe precipitation observed during 33% of those days with precipitation. It is most likely around October 6, when it is observed during 31% of all days.
Light snow is the most severe precipitation observed during 30% of those days with precipitation. It is most likely around January 15, when it is observed during 51% of all days.
Moderate rain is the most severe precipitation observed during 16% of those days with precipitation. It is most likely around October 10, when it is observed during 15% of all days.
During the warm season, which lasts from May 22 to September 17, there is a 53% average chance that precipitation will be observed at some point during a given day. When precipitation does occur it is most often in the form of light rain (49% of days with precipitation have at worst light rain), thunderstorms (26%), and moderate rain (23%).
During the cold season, which lasts from December 4 to March 11, there is a 70% average chance that precipitation will be observed at some point during a given day. When precipitation does occur it is most often in the form of light snow (64% of days with precipitation have at worst light snow), moderate snow (15%), light rain (8%), and heavy snow (7%).
The likelihood of snow falling is highest around January 15, occurring in 67% of days. The season in which it is relatively likely for snow to fall spans from November 4 to April 11.
During peak snow season, accumulation at this location on a given day is just less likely than not. The chances of there being snow on the ground are highest around January 28, occurring 44% of the time. The season in which snow is relatively likely to be on the ground spans from November 26 to March 30.
The snow is typically at its deepest on February 7, with a median depth of 6.6"; the depth exceeds 10.3" only one year out of ten.
The relative humidity typically ranges from 41% (comfortable) to 92% (very humid) over the course of the year, rarely dropping below 24% (dry) and reaching as high as 100% (very humid).
The air is driest around April 28, at which time the relative humidity drops below 50% (mildly humid) three days out of four; it is most humid around September 23, exceeding 88% (very humid) three days out of four.
Dew point is often a better measure of how comfortable a person will find the weather than relative humidity because it more directly relates to whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid.
Over the course of a year, the dew point typically varies from -1°F (dry) to 65°F (mildy humid) and is rarely below -21°F (dry) or above 71°F (muggy).
The time of the year between May 19 and October 3 is the most comfortable, with dew points that are neither too dry nor too muggy.
Over the course of the year typical wind speeds vary from 1 mph to 17 mph (calm to moderate breeze), rarely exceeding 26 mph (strong breeze).
The highest average wind speed of 10 mph (gentle breeze) occurs around January 16, at which time the average daily maximum wind speed is 17 mph (moderate breeze).
The lowest average wind speed of 7 mph (light breeze) occurs around August 4, at which time the average daily maximum wind speed is 13 mph (moderate breeze).