Average Weather in Deltana Alaska, United States
In Deltana, the summers are cool and mostly cloudy and the winters are long, frigid, snowy, and partly cloudy. Over the course of the year, the temperature typically varies from -6°F to 68°F and is rarely below -33°F or above 77°F.
Based on the tourism score, the best time of year to visit Deltana for warm-weather activities is from late June to late July.
The warm season lasts for 3.6 months, from May 18 to September 6, with an average daily high temperature above 56°F. The hottest day of the year is July 7, with an average high of 68°F and low of 52°F.
The cold season lasts for 4.0 months, from November 2 to March 4, with an average daily high temperature below 20°F. The coldest day of the year is January 16, with an average low of -6°F and high of 8°F.
Average High and Low Temperature
The figure below shows you a compact characterization of the entire year of hourly average temperatures. The horizontal axis is the day of the year, the vertical axis is the hour of the day, and the color is the average temperature for that hour and day.
Average Hourly Temperature
In Deltana, 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 in Deltana begins around January 1 and lasts for 3.0 months, ending around April 1. On March 9, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 47% of the time, and overcast or mostly cloudy 53% of the time.
The cloudier part of the year begins around April 1 and lasts for 9.0 months, ending around January 1. On September 27, the cloudiest day of the year, the sky is overcast or mostly cloudy 66% of the time, and clear, mostly clear, or partly cloudy 34% of the time.
Cloud Cover Categories
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in Deltana varies significantly throughout the year.
The wetter season lasts 4.4 months, from May 22 to October 2, with a greater than 25% chance of a given day being a wet day. The chance of a wet day peaks at 45% on July 3.
The drier season lasts 7.6 months, from October 2 to May 22. The smallest chance of a wet day is 5% on March 18.
Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. Based on this categorization, the most common form of precipitation in Deltana changes throughout the year.
Rain alone is the most common for 6.0 months, from April 14 to October 15. The highest chance of a day with rain alone is 45% on July 3.
Snow alone is the most common for 5.9 months, from October 15 to April 14. The highest chance of a day with snow alone is 11% on December 17.
Daily Chance of Precipitation
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. Deltana experiences extreme seasonal variation in monthly rainfall.
The rainy period of the year lasts for 5.7 months, from April 25 to October 16, with a sliding 31-day rainfall of at least 0.5 inches. The most rain falls during the 31 days centered around July 2, with an average total accumulation of 4.1 inches.
The rainless period of the year lasts for 6.3 months, from October 16 to April 25. The least rain falls around December 27, with an average total accumulation of 0.0 inches.
Average Monthly Rainfall
We report snowfall in liquid-equivalent terms. The actual depth of new snowfall is typically between 5 and 10 times the liquid-equivalent amount, assuming the ground is frozen. Colder, drier snow tends to be on the higher end of that range and warmer, wetter snow on the lower end.
As with rainfall, we consider the snowfall accumulated over a sliding 31-day period centered around each day of the year. Deltana experiences some seasonal variation in monthly liquid-equivalent snowfall.
The snowy period of the year lasts for 8.0 months, from September 12 to May 11, with a sliding 31-day liquid-equivalent snowfall of at least 0.1 inches. The most snow falls during the 31 days centered around October 29, with an average total liquid-equivalent accumulation of 0.5 inches.
The snowless period of the year lasts for 4.0 months, from May 11 to September 12. The least snow falls around July 11, with an average total liquid-equivalent accumulation of 0.0 inches.
Average Liquid-Equivalent Monthly Snowfall
The length of the day in Deltana varies extremely over the course of the year. In 2018, the shortest day is December 21, with 4 hours, 16 minutes of daylight; the longest day is June 21, with 20 hours, 55 minutes of daylight.
Hours of Daylight and Twilight
The earliest sunrise is at 3:14 AM on June 20, and the latest sunrise is 7 hours, 17 minutes later at 10:31 AM on December 25. The earliest sunset is at 2:46 PM on December 17, and the latest sunset is 9 hours, 24 minutes later at 12:10 AM on June 21.
Daylight saving time (DST) is observed in Deltana during 2018, starting in the spring on March 11, lasting 7.8 months, and ending in the fall on November 4.
Sunrise & Sunset with Twilight and Daylight Saving Time
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 Deltana, 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.
Humidity Comfort Levels
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 Deltana experiences mild seasonal variation over the course of the year.
The windier part of the year lasts for 4.1 months, from November 17 to March 19, with average wind speeds of more than 5.8 miles per hour. The windiest day of the year is January 8, with an average hourly wind speed of 6.9 miles per hour.
The calmer time of year lasts for 7.9 months, from March 19 to November 17. The calmest day of the year is July 14, with an average hourly wind speed of 4.7 miles per hour.
Average Wind Speed
The predominant average hourly wind direction in Deltana varies throughout the year.
The wind is most often from the west for 1.8 months, from June 6 to July 31, with a peak percentage of 43% on July 18. The wind is most often from the south for 10 months, from July 31 to June 6, with a peak percentage of 64% on January 1.
Best Time of Year to Visit
To characterize how pleasant the weather is in Deltana 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 Deltana for general outdoor tourist activities is from late June to late July, with a peak score in the second 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 Deltana for hot-weather activities is from late June to mid July, with a peak score in the first week of July.
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 Deltana typically lasts for 3.8 months (116 days), from around May 15 to around September 8, rarely starting before April 30 or after May 31, and rarely ending before August 19 or after September 29.
Time Spent in Various Temperature Bands and 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.
Based on growing degree days alone, the first spring blooms in Deltana should appear around June 2, only rarely appearing before May 22 or after June 12.
Growing Degree Days
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 3.4 months, from April 25 to August 4, with an average daily incident shortwave energy per square meter above 4.5 kWh. The brightest day of the year is June 4, with an average of 5.7 kWh.
The darker period of the year lasts for 4.2 months, from October 16 to February 22, with an average daily incident shortwave energy per square meter below 1.2 kWh. The darkest day of the year is December 22, with an average of 0.1 kWh.
Average Daily Incident Shortwave Solar Energy
For the purposes of this report, the geographical coordinates of Deltana are 63.872 deg latitude, -145.218 deg longitude, and 1,230 ft elevation.
The topography within 2 miles of Deltana is essentially flat, with a maximum elevation change of 95 feet and an average elevation above sea level of 1,225 feet. Within 10 miles is essentially flat (4,495 feet). Within 50 miles also contains extreme variations in elevation (12,917 feet).
The area within 2 miles of Deltana is covered by trees (93%), within 10 miles by trees (42%) and cropland (21%), and within 50 miles by trees (39%) and shrubs (27%).
This report illustrates the typical weather in Deltana, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016.
Temperature and Dew Point
There are 2 weather stations near enough to contribute to our estimation of the temperature and dew point in Deltana.
For each station, the records are corrected for the elevation difference between that station and Deltana according to the International Standard Atmosphere , and by the relative change present in the MERRA-2 satellite-era reanalysis between the two locations.
The estimated value at Deltana is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Deltana and a given station.
All data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Tables of the Sun, Moon and Planets , by Jean Meeus.
All other weather data, including cloud cover, precipitation, wind speed and direction, and solar flux, come from NASA's MERRA-2 Modern-Era Retrospective Analysis . This reanalysis combines a variety of wide-area measurements in a state-of-the-art global meteorological model to reconstruct the hourly history of weather throughout the world on a 50-kilometer grid.
Land Use data comes from the Global Land Cover SHARE database , published by the Food and Agriculture Organization of the United Nations.
Elevation data comes from the Shuttle Radar Topography Mission (SRTM) , published by NASA's Jet Propulsion Laboratory.
Names, locations, and time zones of places and some airports come from the GeoNames Geographical Database .
Time zones for aiports and weather stations are provided by AskGeo.com .
Maps are © Esri, with data from National Geographic, Esri, DeLorme, NAVTEQ, UNEP-WCMC, USGS, NASA, ESA, METI, NRCAN, GEBCO, NOAA, and iPC.
The information on this site is provided as is, without any assurances as to its accuracy or suitability for any purpose. Weather data is prone to errors, outages, and other defects. We assume no responsibility for any decisions made on the basis of the content presented on this site.
We draw particular cautious attention to our reliance on the MERRA-2 model-based reconstructions for a number of important data series. While having the tremendous advantages of temporal and spatial completeness, these reconstructions: (1) are based on computer models that may have model-based errors, (2) are coarsely sampled on a 50 km grid and are therefore unable to reconstruct the local variations of many microclimates, and (3) have particular difficulty with the weather in some coastal areas, especially small islands.
We further caution that our travel scores are only as good as the data that underpin them, that weather conditions at any given location and time are unpredictable and variable, and that the definition of the scores reflects a particular set of preferences that may not agree with those of any particular reader.