July Weather at Keflavík International Airport Iceland

Daily high temperatures are around 56°F, rarely falling below 50°F or exceeding 61°F. The highest daily average high temperature is 56°F on July 30.

Daily low temperatures are around 48°F, rarely falling below 44°F or exceeding 52°F. The highest daily average low temperature is 48°F on July 30.

For reference, on July 30, the hottest day of the year, temperatures at Keflavík International Airport typically range from 48°F to 56°F, while on January 25, the coldest day of the year, they range from 29°F to 36°F.

The figure below shows you a compact characterization of the hourly average temperatures for the quarter of the year centered on July. 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, United States (3,898 miles away) is the far-away foreign place with temperatures most similar to Keflavík International Airport (view comparison).

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The month of July at Keflavík International Airport experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 61% throughout the month.

The clearest day of the month is July 5, with clear, mostly clear, or partly cloudy conditions 40% of the time.

For reference, on January 21, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 77%, while on May 20, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 44%.

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. At Keflavík International Airport, the chance of a wet day over the course of July is increasing, starting the month at 26% and ending it at 32%.

For reference, the year's highest daily chance of a wet day is 54% on February 4, and its lowest chance is 26% on July 5.

Rainfall

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

The average sliding 31-day rainfall during July at Keflavík International Airport is increasing, starting the month at 2.1 inches, when it rarely exceeds 3.9 inches or falls below 0.7 inches, and ending the month at 2.7 inches, when it rarely exceeds 4.4 inches or falls below 1.2 inches.

Over the course of July at Keflavík International Airport, the length of the day is very rapidly decreasing. From the start to the end of the month, the length of the day decreases by 2 hours, 45 minutes, implying an average daily decrease of 5 minutes, 29 seconds, and weekly decrease of 38 minutes, 25 seconds.

The shortest day of the month is July 31, with 17 hours, 57 minutes of daylight and the longest day is July 1, with 20 hours, 42 minutes of daylight.

The earliest sunrise of the month at Keflavík International Airport is 3:12 AM on July 1 and the latest sunrise is 1 hour, 24 minutes later at 4:37 AM on July 31.

The latest sunset is 11:54 PM on July 1 and the earliest sunset is 1 hour, 20 minutes earlier at 10:34 PM on July 31.

Daylight saving time is not observed at Keflavík International Airport during 2024.

For reference, on June 20, the longest day of the year, the Sun rises at 3:01 AM and sets 21 hours, 1 minute later, at 12:02 AM, while on December 21, the shortest day of the year, it rises at 11:22 AM and sets 4 hours, 13 minutes later, at 3:35 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 July 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 at Keflavík International Airport is essentially constant during July, 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 at Keflavík International Airport is essentially constant during July, remaining within 0.1 miles per hour of 9.8 miles per hour throughout.

For reference, on January 7, the windiest day of the year, the daily average wind speed is 19.0 miles per hour, while on July 5, the calmest day of the year, the daily average wind speed is 9.7 miles per hour.

The lowest daily average wind speed during July is 9.7 miles per hour on July 5.

The hourly average wind direction at Keflavík International Airport throughout July is predominantly from the north, with a peak proportion of 31% on July 16.

Keflavík International Airport 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 at Keflavík International Airport is essentially constant during July, remaining within 1°F of 51°F throughout.

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 at Keflavík International Airport typically lasts for 5.4 months (164 days), from around May 3 to around October 14, rarely starting before April 15 or after May 21, and rarely ending before September 26 or after November 2.

The month of July at Keflavík International Airport is reliably fully within the growing season.

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 at Keflavík International Airport are gradually increasing during July, increasing by 78°F, from 49°F to 127°F, over the course of the month.

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 at Keflavík International Airport is gradually decreasing during July, falling by 0.9 kWh, from 5.2 kWh to 4.3 kWh, over the course of the month.

For the purposes of this report, the geographical coordinates of Keflavík International Airport are 63.985 deg latitude, -22.606 deg longitude, and 144 ft elevation.

The topography within 2 miles of Keflavík International Airport contains only modest variations in elevation, with a maximum elevation change of 190 feet and an average elevation above sea level of 113 feet. Within 10 miles contains only modest variations in elevation (778 feet). Within 50 miles contains significant variations in elevation (3,537 feet).

The area within 2 miles of Keflavík International Airport is covered by artificial surfaces (81%) and shrubs (16%), within 10 miles by water (51%) and shrubs (31%), and within 50 miles by water (79%) and shrubs (12%).