Climate and Average Weather Year Round in Saint John United States

In Saint John, the summers are hot and mostly clear and the winters are very cold, snowy, windy, and partly cloudy. Over the course of the year, the temperature typically varies from 22°F to 93°F and is rarely below 8°F or above 102°F.

Based on the tourism score, the best time of year to visit Saint John for warm-weather activities is from late May to late September.

The hot season lasts for 3.4 months, from June 2 to September 14, with an average daily high temperature above 83°F. The hottest month of the year in Saint John is July, with an average high of 92°F and low of 68°F.

The cold season lasts for 3.1 months, from November 23 to February 25, with an average daily high temperature below 52°F. The coldest month of the year in Saint John is January, with an average low of 23°F and high of 43°F.

In Saint John, the average percentage of the sky covered by clouds experiences mild seasonal variation over the course of the year.

The clearer part of the year in Saint John begins around May 31 and lasts for 5.2 months, ending around November 6.

The clearest month of the year in Saint John is July, during which on average the sky is clear, mostly clear, or partly cloudy 72% of the time.

The cloudier part of the year begins around November 6 and lasts for 6.8 months, ending around May 31.

The cloudiest month of the year in Saint John is February, during which on average the sky is overcast or mostly cloudy 45% 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 Saint John varies significantly throughout the year.

The wetter season lasts 5.1 months, from April 8 to September 13, with a greater than 23% chance of a given day being a wet day. The month with the most wet days in Saint John is June, with an average of 10.9 days with at least 0.04 inches of precipitation.

The drier season lasts 6.9 months, from September 13 to April 8. The month with the fewest wet days in Saint John is January, with an average of 2.0 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 Saint John changes throughout the year.

Rain alone is the most common for 10 months, from February 3 to December 15. The month with the most days of rain alone in Saint John is June, with an average of 10.9 days.

Snow alone is the most common for 1.6 months, from December 15 to February 3. The month with the most days of snow alone in Saint John is December, with an average of 1.2 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. Saint John experiences significant seasonal variation in monthly rainfall.

The rainy period of the year lasts for 10 months, from February 9 to December 11, with a sliding 31-day rainfall of at least 0.5 inches. The month with the most rain in Saint John is June, with an average rainfall of 3.8 inches.

The rainless period of the year lasts for 1.9 months, from December 11 to February 9. The month with the least rain in Saint John is January, with an average rainfall of 0.2 inches.

Snowfall

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

The snowy period of the year lasts for 4.9 months, from November 13 to April 9, with a sliding 31-day snowfall of at least 1.0 inches. The month with the most snow in Saint John is December, with an average snowfall of 3.4 inches.

The snowless period of the year lasts for 7.1 months, from April 9 to November 13. The least snow falls around July 20, with an average total accumulation of 0.0 inches.

The length of the day in Saint John varies significantly over the course of the year. In 2024, the shortest day is December 21, with 9 hours, 32 minutes of daylight; the longest day is June 20, with 14 hours, 48 minutes of daylight.

The earliest sunrise is at 6:11 AM on June 13, and the latest sunrise is 1 hour, 51 minutes later at 8:02 AM on November 2. The earliest sunset is at 5:15 PM on December 6, and the latest sunset is 3 hours, 47 minutes later at 9:01 PM on June 27.

Daylight saving time (DST) is observed in Saint John during 2024, starting in the spring on March 10, lasting 7.8 months, and ending in the fall on November 3.

The figure below presents a compact representation of key lunar data for 2024. 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.

Saint John experiences significant seasonal variation in the perceived humidity.

The muggier period of the year lasts for 3.3 months, from June 1 to September 11, during which time the comfort level is muggy, oppressive, or miserable at least 8% of the time. The month with the most muggy days in Saint John is July, with 9.6 days that are muggy or worse.

The least muggy day of the year is February 10, when muggy conditions are essentially unheard of.

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 Saint John experiences significant seasonal variation over the course of the year.

The windier part of the year lasts for 3.1 months, from February 22 to May 25, with average wind speeds of more than 11.8 miles per hour. The windiest month of the year in Saint John is April, with an average hourly wind speed of 13.1 miles per hour.

The calmer time of year lasts for 8.9 months, from May 25 to February 22. The calmest month of the year in Saint John is August, with an average hourly wind speed of 10.6 miles per hour.

The predominant average hourly wind direction in Saint John varies throughout the year.

The wind is most often from the south for 8.4 months, from March 10 to November 21, with a peak percentage of 66% on July 4. The wind is most often from the north for 3.6 months, from November 21 to March 10, with a peak percentage of 40% on January 1.

To characterize how pleasant the weather is in Saint John 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 Saint John for general outdoor tourist activities is from late May to late September, with a peak score in the last 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 Saint John for hot-weather activities is from late June to late August, with a peak score in the third week of July.

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 Saint John typically lasts for 6.2 months (190 days), from around April 13 to around October 19, rarely starting before March 25 or after May 1, and rarely ending before September 29 or after November 8.

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 Saint John should appear around March 15, only rarely appearing before March 1 or after April 6.

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 significant seasonal variation over the course of the year.

The brighter period of the year lasts for 3.8 months, from April 23 to August 17, with an average daily incident shortwave energy per square meter above 6.4 kWh. The brightest month of the year in Saint John is June, with an average of 7.2 kWh.

The darker period of the year lasts for 3.1 months, from November 4 to February 8, with an average daily incident shortwave energy per square meter below 3.4 kWh. The darkest month of the year in Saint John is December, with an average of 2.5 kWh.

For the purposes of this report, the geographical coordinates of Saint John are 38.002 deg latitude, -98.760 deg longitude, and 1,900 ft elevation.

The topography within 2 miles of Saint John is essentially flat, with a maximum elevation change of 46 feet and an average elevation above sea level of 1,901 feet. Within 10 miles is essentially flat (203 feet). Within 50 miles contains only modest variations in elevation (968 feet).

The area within 2 miles of Saint John is covered by cropland (82%) and grassland (17%), within 10 miles by cropland (74%) and grassland (26%), and within 50 miles by cropland (64%) and grassland (35%).