Climate and Average Weather Year Round in St. John's Canada

In St. John's, the summers are short and comfortable; the winters are long, freezing, snowy, and windy; and it is partly cloudy year round. Over the course of the year, the temperature typically varies from 19°F to 69°F and is rarely below 8°F or above 78°F.

Based on the tourism score, the best time of year to visit St. John's for warm-weather activities is from mid July to late August.

The warm season lasts for 2.9 months, from June 23 to September 18, with an average daily high temperature above 62°F. The hottest month of the year in St. John's is August, with an average high of 68°F and low of 55°F.

The cold season lasts for 3.9 months, from December 6 to April 2, with an average daily high temperature below 38°F. The coldest month of the year in St. John's is February, with an average low of 20°F and high of 31°F.

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 28 and lasts for 5.5 months, ending around December 10.

The clearest month of the year in St. John's is September, during which on average the sky is clear, mostly clear, or partly cloudy 50% of the time.

The cloudier part of the year begins around December 10 and lasts for 6.6 months, ending around June 28.

The cloudiest month of the year in St. John's is May, during which on average the sky is overcast or mostly cloudy 69% 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 5.8 months, from September 20 to March 13, with a greater than 36% chance of a given day being a wet day. The month with the most wet days in St. John's is November, with an average of 12.1 days with at least 0.04 inches of precipitation.

The drier season lasts 6.2 months, from March 13 to September 20. The month with the fewest wet days in St. John's is August, with an average of 9.8 days with at least 0.04 inches of precipitation.

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 9.5 months, from March 23 to January 7. The month with the most days of rain alone in St. John's is October, with an average of 11.7 days.

Mixed snow and rain is the most common for 1.5 months, from January 7 to January 20 and from February 19 to March 23. The month with the most days of mixed snow and rain in St. John's is February, with an average of 4.0 days.

Snow alone is the most common for 4.3 weeks, from January 20 to February 19. The month with the most days of snow alone in St. John's is February, with an average of 4.1 days.

Rainfall

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 of the year. St. John's experiences significant seasonal variation in monthly rainfall.

Rain falls throughout the year in St. John's. The month with the most rain in St. John's is October, with an average rainfall of 4.2 inches.

The month with the least rain in St. John's is February, with an average rainfall of 1.7 inches.

Snowfall

As with rainfall, we consider the snowfall accumulated over a sliding 31-day period centered around each day of the year. St. John's experiences extreme seasonal variation in monthly snowfall.

The snowy period of the year lasts for 6.4 months, from November 5 to May 17, with a sliding 31-day snowfall of at least 1.0 inches. The month with the most snow in St. John's is February, with an average snowfall of 19.3 inches.

The snowless period of the year lasts for 5.6 months, from May 17 to November 5. The least snow falls around August 8, with an average total accumulation of 0.0 inches.

The length of the day in St. John's varies significantly over the course of the year. In 2023, 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.

The earliest sunrise is at 5:02 AM on June 16, and the latest sunrise is 2 hours, 46 minutes later at 7:48 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 26.

Daylight saving time (DST) is observed in St. John's during 2023, starting in the spring on March 12, lasting 7.8 months, and ending in the fall on November 5.

The figure below presents a compact representation of key lunar data for 2023. The horizontal axis is the day, the vertical axis is the hour of the day, and the colored areas indicate when the moon is above the horizon. The vertical gray bars (new Moons) and blue bars (full Moons) indicate key Moon phases.

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.

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 5.9 months, from October 13 to April 10, with average wind speeds of more than 13.1 miles per hour. The windiest month of the year in St. John's is January, with an average hourly wind speed of 16.1 miles per hour.

The calmer time of year lasts for 6.1 months, from April 10 to October 13. The calmest month of the year in St. John's is July, with an average hourly wind speed of 10.0 miles per hour.

The predominant average hourly wind direction in St. John's varies throughout the year.

The wind is most often from the south for 4.7 months, from April 8 to August 29, with a peak percentage of 43% on July 15. The wind is most often from the west for 7.3 months, from August 29 to April 8, with a peak percentage of 51% on January 1.

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 2.4 months, from July 18 to September 29, with an average temperature above 52°F. The month of the year in St. John's with the warmest water is August, with an average temperature of 57°F.

The time of year with cooler water lasts for 5.0 months, from December 14 to May 16, with an average temperature below 37°F. The month of the year in St. John's with the coolest water is March, with an average temperature of 32°F.

To characterize how pleasant the weather is in St. John's throughout the year, we compute two travel scores.

The tourism score favors clear, rainless days with perceived temperatures between 65°F and 80°F. Based on this score, the best time of year to visit St. John's for general outdoor tourist activities is from mid July to late August, with a peak score in the first week of August.

The beach/pool score favors clear, rainless days with perceived temperatures between 75°F and 90°F. Based on this score, the best time of year to visit St. John's for hot-weather activities is from mid July to mid August, with a peak score in the first week of August.

Methodology

For each hour between 8:00 AM and 9:00 PM of each day in the analysis period (1980 to 2016), independent scores are computed for perceived temperature, cloud cover, and total precipitation. Those scores are combined into a single hourly composite score, which is then aggregated into days, averaged over all the years in the analysis period, and smoothed.

Our cloud cover score is 10 for fully clear skies, falling linearly to 9 for mostly clear skies, and to 1 for fully overcast skies.

Our precipitation score, which is based on the three-hour precipitation centered on the hour in question, is 10 for no precipitation, falling linearly to 9 for trace precipitation, and to 0 for 0.04 inches of precipitation or more.

Our tourism temperature score is 0 for perceived temperatures below 50°F, rising linearly to 9 for 65°F, to 10 for 75°F, falling linearly to 9 for 80°F, and to 1 for 90°F or hotter.

Our beach/pool temperature score is 0 for perceived temperatures below 65°F, rising linearly to 9 for 75°F, to 10 for 82°F, falling linearly to 9 for 90°F, and to 1 for 100°F or hotter.

Definitions of the growing season vary throughout the world, but for the purposes of this report, we define it as the longest continuous period of non-freezing temperatures (≥ 32°F) in the year (the calendar year in the Northern Hemisphere, or from July 1 until June 30 in the Southern Hemisphere).

The growing season in St. John's typically lasts for 5.4 months (164 days), from around May 18 to around October 29, rarely starting before April 27 or after June 9, and rarely ending before October 9 or after November 19.

Growing degree days are a measure of yearly heat accumulation used to predict plant and animal development, and defined as the integral of warmth above a base temperature, discarding any excess above a maximum temperature. In this report, we use a base of 50°F and a cap of 86°F.

Based on growing degree days alone, the first spring blooms in St. John's should appear around June 13, only rarely appearing before May 30 or after June 26.

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 extreme seasonal variation over the course of the year.

The brighter period of the year lasts for 3.3 months, from May 13 to August 22, with an average daily incident shortwave energy per square meter above 5.1 kWh. The brightest month of the year in St. John's is July, with an average of 6.0 kWh.

The darker period of the year lasts for 3.7 months, from October 30 to February 18, with an average daily incident shortwave energy per square meter below 2.0 kWh. The darkest month of the year in St. John's is December, with an average of 1.0 kWh.

For the purposes of this report, the geographical coordinates of St. John's are 47.565 deg latitude, -52.709 deg longitude, and 102 ft elevation.

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 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%).