Summer Weather in Reykjavík Iceland

Daily high temperatures are around 54°F, rarely falling below 46°F or exceeding 62°F. The highest daily average high temperature is 57°F on July 30.

Daily low temperatures are around 46°F, rarely falling below 38°F or exceeding 53°F. The highest daily average low temperature is 49°F on July 26.

For reference, on July 30, the hottest day of the year, temperatures in Reykjavík typically range from 49°F to 57°F, while on January 24, the coldest day of the year, they range from 28°F to 36°F.

The figure below shows you a compact characterization of the hourly average summer temperatures. The horizontal axis is the day, the vertical axis is the hour of the day, and the color is the average temperature for that hour and day.

Sand Point, Alaska, United States (3,898 miles away) and Kodiak, Alaska, United States (3,624 miles) are the far-away foreign places with temperatures most similar to Reykjavík (view comparison).

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The summer in Reykjavík experiences gradually increasing cloud cover, with the percentage of time that the sky is overcast or mostly cloudy increasing from 59% to 65%.

The clearest day of the summer is June 1, with clear, mostly clear, or partly cloudy conditions 41% of the time.

For reference, on January 21, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 78%, while on May 20, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 43%.

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Reykjavík, the chance of a wet day over the course of the summer is very rapidly increasing, starting the season at 30% and ending it at 44%.

For reference, the year's highest daily chance of a wet day is 55% on February 26, and its lowest chance is 29% on July 6.

Rainfall

To show variation within the season and not just the monthly totals, we show the rainfall accumulated over a sliding 31-day period centered around each day.

The average sliding 31-day rainfall during the summer in Reykjavík is rapidly increasing, starting the season at 2.1 inches, when it rarely exceeds 4.0 inches or falls below 0.8 inches, and ending the season at 4.1 inches, when it rarely exceeds 6.3 inches or falls below 2.0 inches.

The lowest average 31-day accumulation is 2.1 inches on June 7.

Over the course of the summer in Reykjavík, the length of the day is very rapidly decreasing. From the start to the end of the season, the length of the day decreases by 5 hours, 33 minutes, implying an average daily decrease of 3 minutes, 40 seconds, and weekly decrease of 25 minutes, 37 seconds.

The shortest day of the summer is August 31, with 14 hours, 37 minutes of daylight and the longest day is June 20, with 21 hours, 8 minutes of daylight.

The earliest sunrise of the summer in Reykjavík is 2:55 AM on June 20 and the latest sunrise is 3 hours, 13 minutes later at 6:08 AM on August 31.

The latest sunset is 12:03 AM on June 21 and the earliest sunset is 3 hours, 18 minutes earlier at 8:45 PM on August 31.

Daylight saving time is not observed in Reykjavík during 2024.

For reference, on June 20, the longest day of the year, the Sun rises at 2:55 AM and sets 21 hours, 8 minutes later, at 12:03 AM, while on December 21, the shortest day of the year, it rises at 11:22 AM and sets 4 hours, 7 minutes later, at 3:29 PM.

The figure below presents a compact representation of the sun's elevation (the angle of the sun above the horizon) and azimuth (its compass bearing) for every hour of every day in the reporting period. The horizontal axis is the day of the year and the vertical axis is the hour of the day. For a given day and hour of that day, the background color indicates the azimuth of the sun at that moment. The black isolines are contours of constant solar elevation.

The figure below presents a compact representation of key lunar data for the summer of 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. The label associated with each bar indicates the date and time that the phase is obtained, and the companion time labels indicate the rise and set times of the Moon for the nearest time interval in which the moon is above the horizon.

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 chance that a given day will be muggy in Reykjavík is essentially constant during the summer, remaining around 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 Reykjavík is gradually increasing during the summer, increasing from 9.1 miles per hour to 9.6 miles per hour over the course of the season.

For reference, on January 7, the windiest day of the year, the daily average wind speed is 16.1 miles per hour, while on July 20, the calmest day of the year, the daily average wind speed is 7.9 miles per hour.

The lowest daily average wind speed during the summer is 7.9 miles per hour on July 20.

The hourly average wind direction in Reykjavík throughout the summer is predominantly from the south, with a peak proportion of 33% on July 24.

Reykjavík 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 surface water temperature in Reykjavík is increasing during the summer, rising by 4°F, from 47°F to 51°F, over the course of the season.

The highest average surface water temperature during the summer is 52°F on August 7.

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 Reykjavík typically lasts for 4.9 months (148 days), from around May 9 to around October 5, rarely starting before April 21 or after May 29, and rarely ending before September 15 or after October 23.

The summer in Reykjavík is very likely fully within the growing season, with the chance that a given day is in the growing season reaching a high of 100% on July 21.

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.

The average accumulated growing degree days in Reykjavík are increasing during the summer, increasing by 227°F, from 14°F to 241°F, over the course of the season.

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 in Reykjavík is very rapidly decreasing during the summer, falling by 2.2 kWh, from 5.1 kWh to 2.9 kWh, over the course of the season.

The highest average daily incident shortwave solar energy during the summer is 5.2 kWh on June 16.

For the purposes of this report, the geographical coordinates of Reykjavík are 64.135 deg latitude, -21.895 deg longitude, and 125 ft elevation.

The topography within 2 miles of Reykjavík contains only modest variations in elevation, with a maximum elevation change of 203 feet and an average elevation above sea level of 57 feet. Within 10 miles contains only modest variations in elevation (2,851 feet). Within 50 miles contains large variations in elevation (4,426 feet).

The area within 2 miles of Reykjavík is covered by artificial surfaces (83%), within 10 miles by water (39%) and shrubs (30%), and within 50 miles by water (53%) and shrubs (23%).