Climate and Average Weather Year Round in Bellingham Washington, United States

In Bellingham, the summers are comfortable and partly cloudy and the winters are very cold, wet, and mostly cloudy. Over the course of the year, the temperature typically varies from 34°F to 74°F and is rarely below 23°F or above 82°F.

Based on the tourism score, the best time of year to visit Bellingham for warm-weather activities is from mid July to mid August.

The warm season lasts for 3.0 months, from June 16 to September 14, with an average daily high temperature above 68°F. The hottest month of the year in Bellingham is August, with an average high of 73°F and low of 55°F.

The cool season lasts for 3.2 months, from November 15 to February 23, with an average daily high temperature below 49°F. The coldest month of the year in Bellingham is December, with an average low of 35°F and high of 44°F.

In Bellingham, 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 Bellingham begins around June 14 and lasts for 3.6 months, ending around October 2.

The clearest month of the year in Bellingham is August, during which on average the sky is clear, mostly clear, or partly cloudy 68% of the time.

The cloudier part of the year begins around October 2 and lasts for 8.4 months, ending around June 14.

The cloudiest month of the year in Bellingham is December, during which on average the sky is overcast or mostly cloudy 71% 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 Bellingham varies significantly throughout the year.

The wetter season lasts 6.4 months, from October 10 to April 21, with a greater than 34% chance of a given day being a wet day. The month with the most wet days in Bellingham is November, with an average of 16.8 days with at least 0.04 inches of precipitation.

The drier season lasts 5.6 months, from April 21 to October 10. The month with the fewest wet days in Bellingham is July, with an average of 3.6 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. The month with the most days of rain alone in Bellingham is November, with an average of 16.4 days. Based on this categorization, the most common form of precipitation throughout the year is rain alone, with a peak probability of 57% on November 17.

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. Bellingham experiences extreme seasonal variation in monthly rainfall.

Rain falls throughout the year in Bellingham. The month with the most rain in Bellingham is November, with an average rainfall of 7.4 inches.

The month with the least rain in Bellingham is July, with an average rainfall of 0.9 inches.

Snowfall

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

The snowy period of the year lasts for 2.5 months, from November 26 to February 10, with a sliding 31-day snowfall of at least 1.0 inches. The month with the most snow in Bellingham is January, with an average snowfall of 2.5 inches.

The snowless period of the year lasts for 9.5 months, from February 10 to November 26. The least snow falls around July 11, with an average total accumulation of 0.0 inches.

The length of the day in Bellingham varies extremely over the course of the year. In 2024, the shortest day is December 21, with 8 hours, 16 minutes of daylight; the longest day is June 20, with 16 hours, 10 minutes of daylight.

The earliest sunrise is at 5:06 AM on June 16, and the latest sunrise is 2 hours, 57 minutes later at 8:03 AM on December 31. The earliest sunset is at 4:13 PM on December 11, and the latest sunset is 5 hours, 4 minutes later at 9:17 PM on June 24.

Daylight saving time (DST) is observed in Bellingham 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.

The perceived humidity level in Bellingham, 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, remaining a virtually constant 0% 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 Bellingham experiences significant seasonal variation over the course of the year.

The windier part of the year lasts for 6.0 months, from October 15 to April 13, with average wind speeds of more than 4.4 miles per hour. The windiest month of the year in Bellingham is December, with an average hourly wind speed of 5.9 miles per hour.

The calmer time of year lasts for 6.0 months, from April 13 to October 15. The calmest month of the year in Bellingham is August, with an average hourly wind speed of 2.9 miles per hour.

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

The wind is most often from the south for 1.5 months, from March 13 to April 28 and for 2.2 months, from August 18 to October 24, with a peak percentage of 40% on March 28. The wind is most often from the west for 3.7 months, from April 28 to August 18, with a peak percentage of 46% on July 2. The wind is most often from the east for 4.6 months, from October 24 to March 13, with a peak percentage of 54% on January 1.

Bellingham 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 some seasonal variation over the course of the year.

The time of year with warmer water lasts for 3.0 months, from June 18 to September 17, with an average temperature above 55°F. The month of the year in Bellingham with the warmest water is August, with an average temperature of 57°F.

The time of year with cooler water lasts for 4.4 months, from November 26 to April 6, with an average temperature below 48°F. The month of the year in Bellingham with the coolest water is January, with an average temperature of 45°F.

To characterize how pleasant the weather is in Bellingham 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 Bellingham for general outdoor tourist activities is from mid July to mid August, with a peak score in the last week of July.

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 Bellingham for hot-weather activities is from late 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 Bellingham typically lasts for 7.0 months (214 days), from around March 31 to around October 31, rarely starting before March 8 or after April 26, and rarely ending before October 11 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 Bellingham should appear around April 25, only rarely appearing before April 9 or after May 16.

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 11 to August 20, with an average daily incident shortwave energy per square meter above 5.5 kWh. The brightest month of the year in Bellingham is July, with an average of 6.5 kWh.

The darker period of the year lasts for 3.9 months, from October 22 to February 19, with an average daily incident shortwave energy per square meter below 2.0 kWh. The darkest month of the year in Bellingham is December, with an average of 0.8 kWh.

For the purposes of this report, the geographical coordinates of Bellingham are 48.760 deg latitude, -122.488 deg longitude, and 66 ft elevation.

The topography within 2 miles of Bellingham contains significant variations in elevation, with a maximum elevation change of 610 feet and an average elevation above sea level of 91 feet. Within 10 miles contains significant variations in elevation (3,061 feet). Within 50 miles contains large variations in elevation (10,768 feet).

The area within 2 miles of Bellingham is covered by artificial surfaces (72%) and water (24%), within 10 miles by trees (32%) and water (26%), and within 50 miles by trees (40%) and water (31%).