Climate and Average Weather Year Round in Hafnarfjörður Iceland

In Hafnarfjörður, the summers are short, cold, and mostly cloudy and the winters are long, very cold, snowy, windy, and overcast. Over the course of the year, the temperature typically varies from 28°F to 56°F and is rarely below 17°F or above 62°F.

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

The warm season lasts for 2.9 months, from June 9 to September 5, with an average daily high temperature above 52°F. The hottest month of the year in Hafnarfjörður is July, with an average high of 56°F and low of 48°F.

The cold season lasts for 4.9 months, from November 8 to April 3, with an average daily high temperature below 40°F. The coldest month of the year in Hafnarfjörður is January, with an average low of 28°F and high of 36°F.

In Hafnarfjörður, 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 Hafnarfjörður begins around March 31 and lasts for 7.2 months, ending around November 7.

The clearest month of the year in Hafnarfjörður is May, during which on average the sky is clear, mostly clear, or partly cloudy 42% of the time.

The cloudier part of the year begins around November 7 and lasts for 4.8 months, ending around March 31.

The cloudiest month of the year in Hafnarfjörður is January, during which on average the sky is overcast or mostly cloudy 77% 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 Hafnarfjörður varies throughout the year.

The wetter season lasts 7.8 months, from August 25 to April 18, with a greater than 42% chance of a given day being a wet day. The month with the most wet days in Hafnarfjörður is February, with an average of 15.9 days with at least 0.04 inches of precipitation.

The drier season lasts 4.2 months, from April 18 to August 25. The month with the fewest wet days in Hafnarfjörður is June, with an average of 9.0 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. The month with the most days of rain alone in Hafnarfjörður is September, with an average of 13.9 days. Based on this categorization, the most common form of precipitation throughout the year is rain alone, with a peak probability of 47% on September 20.

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. Hafnarfjörður experiences significant seasonal variation in monthly rainfall.

Rain falls throughout the year in Hafnarfjörður. The month with the most rain in Hafnarfjörður is September, with an average rainfall of 4.7 inches.

The month with the least rain in Hafnarfjörður is June, with an average rainfall of 2.3 inches.

Snowfall

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

The snowy period of the year lasts for 6.1 months, from October 22 to April 26, with a sliding 31-day snowfall of at least 1.0 inches. The month with the most snow in Hafnarfjörður is January, with an average snowfall of 10.5 inches.

The snowless period of the year lasts for 5.9 months, from April 26 to October 22. The least snow falls around July 23, with an average total accumulation of 0.0 inches.

The length of the day in Hafnarfjörður varies extremely over the course of the year. In 2024, the shortest day is December 21, with 4 hours, 10 minutes of daylight; the longest day is June 20, with 21 hours, 5 minutes of daylight.

The earliest sunrise is at 2:57 AM on June 20, and the latest sunrise is 8 hours, 25 minutes later at 11:22 AM on December 24. The earliest sunset is at 3:30 PM on December 17, and the latest sunset is 8 hours, 32 minutes later at 12:02 AM on June 21.

Daylight saving time (DST) is not observed in Hafnarfjörður during 2024.

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 Hafnarfjörður, 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 Hafnarfjörður experiences extreme seasonal variation over the course of the year.

The windier part of the year lasts for 6.1 months, from October 21 to April 25, with average wind speeds of more than 12.1 miles per hour. The windiest month of the year in Hafnarfjörður is January, with an average hourly wind speed of 16.0 miles per hour.

The calmer time of year lasts for 5.9 months, from April 25 to October 21. The calmest month of the year in Hafnarfjörður is July, with an average hourly wind speed of 8.0 miles per hour.

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

The wind is most often from the south for 1.0 weeks, from February 26 to March 4; for 1.4 weeks, from April 16 to April 26; and for 4.4 months, from May 6 to September 17, with a peak percentage of 32% on July 24. The wind is most often from the east for 1.4 months, from March 4 to April 16; for 1.4 weeks, from April 26 to May 6; and for 5.0 months, from September 25 to February 26, with a peak percentage of 31% on March 8. The wind is most often from the north for 1.1 weeks, from September 17 to September 25, with a peak percentage of 29% on September 23.

Hafnarfjörður 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 2.6 months, from June 23 to September 12, with an average temperature above 50°F. The month of the year in Hafnarfjörður with the warmest water is August, with an average temperature of 52°F.

The time of year with cooler water lasts for 5.2 months, from November 27 to May 2, with an average temperature below 43°F. The month of the year in Hafnarfjörður with the coolest water is March, with an average temperature of 41°F.

To characterize how pleasant the weather is in Hafnarfjörður 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 Hafnarfjörður for general outdoor tourist activities is from early 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 Hafnarfjörður 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 Hafnarfjörður typically lasts for 4.8 months (147 days), from around May 10 to around October 4, rarely starting before April 21 or after May 29, and rarely ending before September 15 or after October 22.

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 Hafnarfjörður should appear around July 15, only rarely appearing before June 29 or after August 9.

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 2.8 months, from May 5 to July 31, with an average daily incident shortwave energy per square meter above 4.2 kWh. The brightest month of the year in Hafnarfjörður is June, with an average of 5.1 kWh.

The darker period of the year lasts for 4.8 months, from October 10 to March 4, with an average daily incident shortwave energy per square meter below 1.1 kWh. The darkest month of the year in Hafnarfjörður is December, with an average of 0.0 kWh.

For the purposes of this report, the geographical coordinates of Hafnarfjörður are 64.067 deg latitude, -21.938 deg longitude, and 66 ft elevation.

The topography within 2 miles of Hafnarfjörður contains only modest variations in elevation, with a maximum elevation change of 446 feet and an average elevation above sea level of 129 feet. Within 10 miles contains only modest variations in elevation (2,034 feet). Within 50 miles contains large variations in elevation (4,423 feet).

The area within 2 miles of Hafnarfjörður is covered by artificial surfaces (45%) and shrubs (43%), within 10 miles by shrubs (43%) and water (31%), and within 50 miles by water (58%) and shrubs (21%).