Climate and Average Weather Year Round at Port Alexander Seaplane Base Alaska, United States

At Port Alexander Seaplane Base, the summers are cool and mostly cloudy; the winters are long, very cold, extremely windy, and overcast; and it is wet year round. Over the course of the year, the temperature typically varies from 35°F to 59°F and is rarely below 24°F or above 67°F.

Based on the tourism score, the best time of year to visit Port Alexander Seaplane Base for warm-weather activities is from late July to mid August.

The warm season lasts for 3.5 months, from May 26 to September 10, with an average daily high temperature above 56°F. The hottest month of the year at Port Alexander Seaplane Base is August, with an average high of 59°F and low of 50°F.

The cool season lasts for 4.6 months, from November 10 to March 30, with an average daily high temperature below 47°F. The coldest month of the year at Port Alexander Seaplane Base is February, with an average low of 36°F and high of 44°F.

At Port Alexander Seaplane Base, the average percentage of the sky covered by clouds experiences mild seasonal variation over the course of the year.

The clearer part of the year at Port Alexander Seaplane Base begins around April 20 and lasts for 5.1 months, ending around September 24.

The clearest month of the year at Port Alexander Seaplane Base is August, during which on average the sky is clear, mostly clear, or partly cloudy 40% of the time.

The cloudier part of the year begins around September 24 and lasts for 6.9 months, ending around April 20.

The cloudiest month of the year at Port Alexander Seaplane Base is January, during which on average the sky is overcast or mostly cloudy 76% 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 at Port Alexander Seaplane Base varies significantly throughout the year.

The wetter season lasts 7.0 months, from August 26 to March 25, with a greater than 54% chance of a given day being a wet day. The month with the most wet days at Port Alexander Seaplane Base is October, with an average of 21.8 days with at least 0.04 inches of precipitation.

The drier season lasts 5.0 months, from March 25 to August 26. The month with the fewest wet days at Port Alexander Seaplane Base is June, with an average of 11.1 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 at Port Alexander Seaplane Base is October, with an average of 21.7 days. Based on this categorization, the most common form of precipitation throughout the year is rain alone, with a peak probability of 72% on October 30.

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. Port Alexander Seaplane Base experiences extreme seasonal variation in monthly rainfall.

Rain falls throughout the year at Port Alexander Seaplane Base. The month with the most rain at Port Alexander Seaplane Base is October, with an average rainfall of 12.9 inches.

The month with the least rain at Port Alexander Seaplane Base is June, with an average rainfall of 3.7 inches.

Snowfall

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

The snowy period of the year lasts for 1.9 months, from December 29 to February 25, with a sliding 31-day snowfall of at least 1.0 inches. The month with the most snow at Port Alexander Seaplane Base is January, with an average snowfall of 1.5 inches.

The snowless period of the year lasts for 10 months, from February 25 to December 29. The least snow falls around August 1, with an average total accumulation of 0.0 inches.

The length of the day at Port Alexander Seaplane Base varies extremely over the course of the year. In 2024, the shortest day is December 21, with 6 hours, 53 minutes of daylight; the longest day is June 20, with 17 hours, 41 minutes of daylight.

The earliest sunrise is at 4:09 AM on June 17, and the latest sunrise is 4 hours, 22 minutes later at 8:31 AM on December 28. The earliest sunset is at 3:21 PM on December 14, and the latest sunset is 6 hours, 29 minutes later at 9:51 PM on June 23.

Daylight saving time (DST) is observed at Port Alexander Seaplane Base 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 at Port Alexander Seaplane Base, 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 at Port Alexander Seaplane Base experiences extreme seasonal variation over the course of the year.

The windier part of the year lasts for 6.8 months, from September 24 to April 18, with average wind speeds of more than 13.7 miles per hour. The windiest month of the year at Port Alexander Seaplane Base is December, with an average hourly wind speed of 17.6 miles per hour.

The calmer time of year lasts for 5.2 months, from April 18 to September 24. The calmest month of the year at Port Alexander Seaplane Base is July, with an average hourly wind speed of 9.7 miles per hour.

The predominant average hourly wind direction at Port Alexander Seaplane Base varies throughout the year.

The wind is most often from the south for 2.4 months, from March 30 to June 13 and for 4.1 months, from August 12 to December 16, with a peak percentage of 43% on October 7. The wind is most often from the west for 2.0 months, from June 13 to August 12, with a peak percentage of 43% on July 15. The wind is most often from the east for 3.5 months, from December 16 to March 30, with a peak percentage of 39% on January 1.

Port Alexander Seaplane Base 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 2.5 months, from July 7 to September 22, with an average temperature above 52°F. The month of the year at Port Alexander Seaplane Base with the warmest water is August, with an average temperature of 54°F.

The time of year with cooler water lasts for 4.5 months, from December 20 to May 4, with an average temperature below 45°F. The month of the year at Port Alexander Seaplane Base with the coolest water is March, with an average temperature of 42°F.

To characterize how pleasant the weather is at Port Alexander Seaplane Base 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 Port Alexander Seaplane Base for general outdoor tourist activities is from late July to mid August, with a peak score in the first week of August.

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 Port Alexander Seaplane Base for hot-weather activities is from late July to mid 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 at Port Alexander Seaplane Base typically lasts for 7.3 months (224 days), from around March 22 to around November 1, rarely starting before February 20 or after May 2, and rarely ending before October 4 or after December 10.

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 at Port Alexander Seaplane Base should appear around June 10, only rarely appearing before May 20 or after July 19.

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 3.2 months, from May 6 to August 12, with an average daily incident shortwave energy per square meter above 4.4 kWh. The brightest month of the year at Port Alexander Seaplane Base is June, with an average of 5.4 kWh.

The darker period of the year lasts for 4.3 months, from October 14 to February 23, with an average daily incident shortwave energy per square meter below 1.3 kWh. The darkest month of the year at Port Alexander Seaplane Base is December, with an average of 0.3 kWh.

For the purposes of this report, the geographical coordinates of Port Alexander Seaplane Base are 56.247 deg latitude, -134.648 deg longitude, and 13 ft elevation.

The topography within 2 miles of Port Alexander Seaplane Base contains very significant variations in elevation, with a maximum elevation change of 1,699 feet and an average elevation above sea level of 209 feet. Within 10 miles contains very significant variations in elevation (3,015 feet). Within 50 miles contains large variations in elevation (4,426 feet).

The area within 2 miles of Port Alexander Seaplane Base is covered by water (56%) and trees (44%), within 10 miles by water (77%) and trees (19%), and within 50 miles by water (75%) and trees (19%).