Average Weather in St. John's Canada
In St. John's, the temperature typically varies from 18°F to 69°F over the course of the year, and is rarely below 7°F or above 78°F.
The warm season lasts for 88 days, from June 22 to September 18, with an average daily high temperature above 61°F. The hottest day of the year is August 2, with an average high of 69°F and low of 56°F.
The cold season lasts for 117 days, from December 6 to April 2, with an average daily high temperature below 38°F. The coldest day of the year is January 31, with an average low of 18°F and high of 30°F.
Average High and Low Temperature
The figure below shows you a compact characterization of the entire year of hourly average temperatures. The horizontal axis is the day of the year, the vertical axis is the hour of the day, and the color is the average temperature for that hour and day.
Average Hourly Temperature
The length of the day in St. John's varies significantly over the course of the year. In 2017, the shortest day is December 21, with 8 hours, 26 minutes of daylight; the longest day is June 21, with 15 hours, 59 minutes of daylight.
Hours of Daylight and Twilight
The earliest sunrise is at 5:02 AM on June 16, and the latest sunrise is 2 hours, 47 minutes later at 7:49 AM on November 4. The earliest sunset is at 4:09 PM on December 11, and the latest sunset is 4 hours, 53 minutes later at 9:02 PM on June 25.
Daylight saving time (DST) is observed in St. John's during 2017, starting in the spring on March 12, lasting 237 days, and ending in the fall on November 5.
Sunrise & Sunset with Twilight and Daylight Saving Time
In St. John's, the average percentage of the sky covered by clouds experiences significant seasonal variation over the course of the year.
The clearer part of the year in St. John's begins around June 27 and lasts for 167 days, ending around December 11. On September 15, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 51% of the time, and overcast or mostly cloudy 49% of the time.
The cloudier part of the year begins around December 11 and lasts for 198 days, ending around June 27. On May 9, the cloudiest day of the year, the sky is overcast or mostly cloudy 70% of the time, and clear, mostly clear, or partly cloudy 30% of the time.
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in St. John's varies throughout the year.
The wetter season lasts 174 days, from September 20 to March 13, with a greater than 36% chance of a given day being a wet day. The chance of a wet day peaks at 42% on November 22.
The drier season lasts 191 days, from March 13 to September 20. The smallest chance of a wet day is 30% on August 13.
Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. Based on this categorization, the most common form of precipitation in St. John's changes throughout the year.
Rain alone is the most common for 283 days, from March 26 to January 3. The highest chance of a day with rain alone is 38% on October 26.
Mixed snow and rain is the most common for 53 days, from January 3 to January 20 and from February 18 to March 26. The highest chance of a day with mixed snow and rain is 16% on February 28.
Snow alone is the most common for 29 days, from January 20 to February 18. The highest chance of a day with snow alone is 18% on February 1.
Daily Chance of Precipitation
To show variation within the months and not just the monthly totals, we show the rainfall accumulated over a sliding 31-day period centered around each day in the year. St. John's experiences significant seasonal variation in monthly rainfall.
Rain falls throughout the year in St. John's. The most rain falls during the 31 days centered around October 16, with an average total accumulation of 4.2 inches.
The least rain falls around February 9, with and average total accumulation of 1.5 inches.
Average Monthly Rainfall
We report snowfall in liquid-equivalent terms. The actual depth of new snowfall is typically between 5 and 10 times the liquid-equivalent amount, assuming the ground is frozen. Colder, drier snow tends to be on the higher end of that range and warmer, wetter snow on the lower end.
As with rainfall, we consider the snowfall accumulated over a sliding 31-day period centered around each day in the year. St. John's experiences very significant seasonal variation in monthly liquid-equivalent snowfall.
The snowy period of the year lasts for 194 days, from November 4 to May 17, with a sliding 31-day liquid-equivalent snowfall of at least 0.1 inches. The most snow falls during the 31 days centered around February 3, with an average total liquid-equivalent accumulation of 2.1 inches.
The snowless period of the year lasts for 171 days, from May 17 to November 4. The least snow falls around August 16, with an average total liquid-equivalent accumulation of 0.0 inches.
Average Liquid-Equivalent Monthly Snowfall
We base the humidity comfort level on the dew point, as it determines whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid. Unlike temperature, which typically varies significantly between night and day, dew point tends to change more slowly, so while the temperature may drop at night, a muggy day is typically followed by a muggy night.
The perceived humidity level in St. John's, as measured by the percentage of time in which the humidity comfort level is muggy, oppressive, or miserable, does not vary significantly over the course of the year, staying within 3% of 3% throughout.
Humidity Comfort Levels
This section discusses the wide-area hourly average wind vector (speed and direction) at 10 meters above the ground. The wind experienced at any given location is highly dependent on local topography and other factors, and instantaneous wind speed and direction vary more widely than hourly averages.
The average hourly wind speed in St. John's experiences significant seasonal variation over the course of the year.
The windier part of the year lasts for 180 days, from October 12 to April 10, with average wind speeds of more than 7.0 miles per hour. The windiest day of the year is January 14, with an average hourly wind speed of 8.8 miles per hour.
The calmer time of year lasts for 185 days, from April 10 to October 12. The calmest day of the year is August 2, with an average hourly wind speed of 5.3 miles per hour.
Average Wind Speed
The predominant average hourly wind direction in St. John's varies throughout the year.
The wind is most often from the south for 143 days, from April 8 to August 29, with a peak percentage of 43% on July 16. The wind is most often from the west for 222 days, from August 29 to April 8, with a peak percentage of 52% on January 11.
St. John's is located near a large body of water (e.g., ocean, sea, or large lake). This section reports on the wide-area average surface temperature of that water.
The average water temperature experiences significant seasonal variation over the course of the year.
The time of year with warmer water lasts for 75 days, from July 17 to September 30, with an average temperature above 52°F. The day of the year with the warmest water is August 20, with an average temperature of 57°F.
The time of year with cooler water lasts for 153 days, from December 14 to May 16, with an average temperature below 37°F. The day of the year with the coolest water is March 5, with an average temperature of 31°F.
Average Water Temperature
This section discusses the total daily incident shortwave solar energy reaching the surface of the ground over a wide area, taking full account of seasonal variations in the length of the day, the elevation of the Sun above the horizon, and absorption by clouds and other atmospheric constituents. Shortwave radiation includes visible light and ultraviolet radiation.
The average daily incident shortwave solar energy experiences very significant seasonal variation over the course of the year.
The brighter period of the year lasts for 101 days, from May 13 to August 22, with an average daily incident shortwave energy per square meter above 5.1 kWh. The brightest day of the year is July 11, with an average of 6.1 kWh.
The darker period of the year lasts for 113 days, from October 29 to February 19, with an average daily incident shortwave energy per square meter below 2.0 kWh. The darkest day of the year is December 21, with an average of 0.9 kWh.
Average Daily Incident Shortwave Solar Energy
For the purposes of this report, the geographical coordinates of St. John's are 47.565 deg latitude, -52.709 deg longitude, and 243 ft elevation (map ).
The topography within 2 miles of St. John's contains significant variations in elevation, with a maximum elevation change of 741 feet, and an average elevation above sea level of 214 feet. Within 10 miles contains very significant variations in elevation (846 feet). Within 50 miles also contains very significant variations in elevation (1,093 feet).
The area within 2 miles of St. John's is covered by sparse vegetation (34%), artificial surfaces (33%), trees (20%), and water (11%), within 10 miles by water (44%) and trees (34%), and within 50 miles by water (72%) and trees (16%).
This report illustrates the typical weather in St. John's, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016.
Temperature and Dew Point
There are 2 weather stations near enough to contribute to our estimation of the temperature and dew point in St. John's.
For each station, the records are corrected for the elevation difference between that station and St. John's according to the International Standard Atmosphere , and by the relative change present in the MERRA-2 satellite-era reanalysis between the two locations.
The estimated value at St. John's is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between St. John's and a given station.
All data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Tables of the Sun, Moon and Planets , by Jean Meeus.
All other weather data, including cloud cover, precipitation, wind speed and direction, and solar flux, come from NASA's MERRA-2 Modern-Era Retrospective Analysis . This reanalysis combines a variety of wide-area measurements in a state-of-the-art global meteorological model to reconstruct the hourly history of weather throughout the world on a 50-kilometer grid.
Land Use data comes from the Global Land Cover SHARE database , published by the Food and Agriculture Organization of the United Nations.
Elevation data comes from the Shuttle Radar Topography Mission (SRTM) , published by NASA's Jet Propulsion Laboratory.
Names, locations, and time zones of places and some airports come from the GeoNames Geographical Database .
Time zones for aiports and weather stations are provided by AskGeo.com .