Average Weather For Fort Greely/Delta Junction, Alaska, USA

Location

This report describes the typical weather at the Allen Army Airfield (Big Delta Army Airfield) (Fort Greely/Delta Junction, Alaska, United States) weather station over the course of an average year. It is based on the historical records from 1974 to 2012. Earlier records are either unavailable or unreliable.

Fort Greely/Delta Junction, Alaska has a continental climate with dry winters and short cool summers. The area within 25 mi of this station is covered by forests (78%), tundra (20%), and lakes and rivers (3%).

Temperature

Over the course of a year, the temperature typically varies from -8°F to 69°F and is rarely below -35°F or above 78°F.

Daily High and Low Temperature

The daily average low (blue) and high (red) temperature with percentile bands (inner band from 25th to 75th percentile, outer band from 10th to 90th percentile).

The warm season lasts from May 13 to September 10 with an average daily high temperature above 56°F. The hottest day of the year is July 9, with an average high of 69°F and low of 52°F.

The cold season lasts from November 4 to February 29 with an average daily high temperature below 17°F. The coldest day of the year is January 5, with an average low of -8°F and high of 4°F.

Fraction of Time Spent in Various Temperature Bands

The average fraction of time spent in various temperature bands: frigid (below 15°F), freezing (15°F to 32°F), cold (32°F to 50°F), cool (50°F to 65°F), comfortable (65°F to 75°F), warm (75°F to 85°F), hot (85°F to 100°F) and sweltering (above 100°F).

Sun

The length of the day varies significantly over the course of the year. The shortest day is December 21 with 4:13 hours of daylight; the longest day is June 20 with 21:00 hours of daylight.

Daily Hours of Daylight and Twilight

The number of hours during which the Sun is visible (black line), with various degrees of daylight, twilight, and night, indicated by the color bands. From bottom (most yellow) to top (most gray): full daylight, solar twilight (Sun is visible but less than 6° from the horizon), civil twilight (Sun is not visible but is less than 6° below the horizon), nautical twilight (Sun is between 6° and 12° below the horizon), astronomical twilight (Sun is between 12° and 18° below the horizon), and full night.

The earliest sunrise is at 3:14am on June 16 and the latest sunset is at 12:16am on June 24. The latest sunrise is at 10:36am on December 24 and the earliest sunset is at 2:46pm on December 17.

Daylight saving time (DST) is observed in this location during 2012, starting in the spring on March 11 and ending in the fall on November 4.

Daily Sunrise & Sunset with Twilight and Daylight Saving Time

The solar day over the course of the year 2012 . From bottom to top, the black lines are the previous solar midnight, sunrise, solar noon, sunset, and the next solar midnight. The day, twilights (solar, civil, nautical, and astronomical), and night are indicated by the color bands from yellow to gray. The transitions to and from daylight saving time are indicated by the "DST" labels.

Clouds

The median cloud cover ranges from 55% (partly cloudy) to 84% (mostly cloudy). The sky is cloudiest on July 27 and clearest on March 12. The clearer part of the year begins around December 5. The cloudier part of the year begins around May 2.

Median Cloud Cover

The median daily cloud cover (black line) with percentile bands (inner band from 40th to 60th percentile, outer band from 25th to 75th percentile).

On March 12, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 38% of the time, and overcast or mostly cloudy 38% of the time.

On July 27, the cloudiest day of the year, the sky is overcast, mostly cloudy, or partly cloudy 66% of the time, and clear or mostly clear 11% of the time.

Cloud Cover Types

The fraction of time spent in each of the five sky cover categories. From top (most blue) to bottom (most gray), the categories are clear, mostly clear, partly cloudy, mostly cloudy, and overcast. Pink indicates missing data. Outside of the United States clear skies are often reported ambiguously, leading them to be lumped in with the missing data.

Precipitation

The probability that precipitation will be observed at this location varies throughout the year. Precipitation is most likely around July 14, occurring in 45% of days. Precipitation is least likely around March 30, occurring in 25% of days.

Probability of Precipitation at Some Point in the Day

The fraction of days in which various types of precipitation are observed. If more than one type of precipitation is reported in a given day, the more severe precipitation is counted. For example, if light rain is observed in the same day as a thunderstorm, that day counts towards the thunderstorm totals. The order of severity is from the top down in this graph, with the most severe at the bottom.

Over the entire year, the most common forms of precipitation are light snow and light rain.

Light snow is the most severe precipitation observed during 51% of those days with precipitation. It is most likely around November 6, when it is observed during 38% of all days.

Light rain is the most severe precipitation observed during 31% of those days with precipitation. It is most likely around August 3, when it is observed during 31% of all days.

Types of Precipitation Throughout the Year

Relative frequency of various types of precipitation over the course of a typical year.

During the warm season, which lasts from May 13 to September 10, there is a 41% average chance that precipitation will be observed at some point during a given day. When precipitation does occur it is most often in the form of light rain (67% of days with precipitation have at worst light rain), moderate rain (15%), and thunderstorms (10%).

During the cold season, which lasts from November 4 to February 29, there is a 37% average chance that precipitation will be observed at some point during a given day. When precipitation does occur it is most often in the form of light snow (89% of days with precipitation have at worst light snow) and moderate snow (8%).

Warm Season Precipitation

Cold Season Precipitation

Relative frequency of various types of precipitation during the warm and cold seasons respectively.

Snow

The likelihood of snow falling is highest around November 6, occurring in 42% of days. The season in which it is relatively likely for snow to fall spans from September 16 to April 29.

Probability of Snow Fall Being Reported in a Given Day

Probability that snow will be reported at least once in a given day. The season is defined as the period during which the probability is greater than one third the maximum probability.

Either snow rarely accumulates at this location or snow depth measurements are unavailable or unreliable.

Humidity

The relative humidity typically ranges from 31% (comfortable) to 90% (very humid) over the course of the year, rarely dropping below 18% (dry) and reaching as high as 100% (very humid).

The air is driest around May 16, at which time the relative humidity drops below 37% (comfortable) three days out of four; it is most humid around October 18, exceeding 86% (very humid) three days out of four.

Relative Humidity

The average daily high (blue) and low (brown) relative humidity with percentile bands (inner bands from 25th to 75th percentile, outer bands from 10th to 90th percentile).

Dew Point

Dew point is often a better measure of how comfortable a person will find the weather than relative humidity because it more directly relates to whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid.

Over the course of a year, the dew point typically varies from -15°F (dry) to 51°F (very comfortable) and is rarely below -39°F (dry) or above 56°F (comfortable).

The time of the year between July 6 and July 31 is the most comfortable, with dew points that are neither too dry nor too muggy.

Dew Point

The daily average low (blue) and high (red) dew point with percentile bands (inner band from 25th to 75th percentile, outer band from 10th to 90th percentile).

Wind

Over the course of the year typical wind speeds vary from 0 mph to 22 mph (calm to fresh breeze), rarely exceeding 35 mph (high wind).

The highest average wind speed of 12 mph (moderate breeze) occurs around January 18, at which time the average daily maximum wind speed is 22 mph (fresh breeze).

The lowest average wind speed of 6 mph (light breeze) occurs around July 10, at which time the average daily maximum wind speed is 11 mph (gentle breeze).

Wind Speed

The average daily minimum (red), maximum (green), and average (black) wind speed with percentile bands (inner band from 25th to 75th percentile, outer band from 10th to 90th percentile).
The wind is most often out of the east (27% of the time), west (16% of the time), south west (11% of the time), and south (11% of the time). The wind is least often out of the north east (3% of the time) and north (3% of the time).

Wind Directions Over the Entire Year

The fraction of time spent with the wind blowing from the various directions over the entire year. Values do not sum to 100% because the wind direction is undefined when the wind speed is zero.

Fraction of Time Spent with Various Wind Directions

The fraction of time spent with the wind blowing from the various directions on a daily basis. Stacked values do not always sum to 100% because the wind direction is undefined when the wind speed is zero.