September Weather in Höfn Iceland

Daily high temperatures decrease by 5°F, from 53°F to 48°F, rarely falling below 41°F or exceeding 57°F.

Daily low temperatures decrease by 5°F, from 45°F to 40°F, rarely falling below 33°F or exceeding 50°F.

For reference, on August 3, the hottest day of the year, temperatures in Höfn typically range from 48°F to 55°F, while on December 26, the coldest day of the year, they range from 29°F to 37°F.

The figure below shows you a compact characterization of the hourly average temperatures for the quarter of the year centered on September. 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.

Unalaska, United States (4,137 miles away) is the far-away foreign place with temperatures most similar to Höfn (view comparison).

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The month of September in Höfn experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 63% throughout the month.

The clearest day of the month is September 1, with clear, mostly clear, or partly cloudy conditions 38% of the time.

For reference, on January 16, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 70%, while on May 22, 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 Höfn, the chance of a wet day over the course of September is rapidly increasing, starting the month at 42% and ending it at 49%.

For reference, the year's highest daily chance of a wet day is 55% on January 6, and its lowest chance is 29% on May 30.

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 September in Höfn is rapidly increasing, starting the month at 5.2 inches, when it rarely exceeds 8.4 inches or falls below 2.4 inches, and ending the month at 6.9 inches, when it rarely exceeds 10.6 inches or falls below 3.9 inches.

Over the course of September in Höfn, 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 3 hours, 8 minutes, implying an average daily decrease of 6 minutes, 28 seconds, and weekly decrease of 45 minutes, 19 seconds.

The shortest day of the month is September 30, with 11 hours, 23 minutes of daylight and the longest day is September 1, with 14 hours, 31 minutes of daylight.

The earliest sunrise of the month in Höfn is 5:44 AM on September 1 and the latest sunrise is 1 hour, 24 minutes later at 7:08 AM on September 30.

The latest sunset is 8:15 PM on September 1 and the earliest sunset is 1 hour, 44 minutes earlier at 6:31 PM on September 30.

Daylight saving time is not observed in Höfn during 2024.

For reference, on June 20, the longest day of the year, the Sun rises at 2:25 AM and sets 21 hours, 15 minutes later, at 11:39 PM, while on December 21, the shortest day of the year, it rises at 10:57 AM and sets 4 hours, 3 minutes later, at 3:00 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 September 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 Höfn is essentially constant during September, remaining around 0% throughout.

For reference, on July 16, the muggiest day of the year, there are muggy conditions 0% of the time, while on January 1, the least muggy day of the year, there are muggy conditions 0% of the time.

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 Höfn is rapidly increasing during September, increasing from 13.3 miles per hour to 15.8 miles per hour over the course of the month.

For reference, on December 31, the windiest day of the year, the daily average wind speed is 19.7 miles per hour, while on July 21, the calmest day of the year, the daily average wind speed is 10.4 miles per hour.

The hourly average wind direction in Höfn throughout September is predominantly from the north, with a peak proportion of 36% on September 26.

Höfn 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 Höfn is gradually decreasing during September, falling by 3°F, from 49°F to 47°F, over the course of the month.

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 Höfn typically lasts for 5.2 months (159 days), from around May 2 to around October 9, rarely starting before April 13 or after May 21, and rarely ending before September 13 or after November 1.

The month of September in Höfn is more likely than not fully within the growing season, with the chance that a given day is in the growing season rapidly decreasing from 97% to 67% over the course of the month.

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 Höfn are essentially constant during September, remaining within 10°F of 166°F throughout.

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 Höfn is decreasing during September, falling by 1.4 kWh, from 2.9 kWh to 1.4 kWh, over the course of the month.

For the purposes of this report, the geographical coordinates of Höfn are 64.254 deg latitude, -15.212 deg longitude, and 3 ft elevation.

The topography within 2 miles of Höfn is essentially flat, with a maximum elevation change of 30 feet and an average elevation above sea level of 1 feet. Within 10 miles is essentially flat (3,330 feet). Within 50 miles also contains extreme variations in elevation (6,864 feet).

The area within 2 miles of Höfn is covered by bare soil (58%) and sparse vegetation (19%), within 10 miles by water (43%) and bare soil (20%), and within 50 miles by water (54%) and snow and glaciers (19%).