Delta Junction, Alaska climate: Normal weather by month, frost dates and records
Delta Junction's normal year runs from −8°F January nights to 70°F July afternoons, with 10.3 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of −1.1°C, January lows of −22°C, July highs of 21°C, 261 mm of precipitation a year.
- NOAA stationBig Delta Airport
- Station IDUSW00026415
- Location63.99°N 145.72°W
- Elevation1,277 ft (389 m)
- Population985
On October 23, the normal high in Delta Junction is 28°F and the normal low 14°F, and the chance of measurable rain or snow is 25%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Delta Junction.
- Jan 6° -8°
- Feb 16° -1°
- Mar 25° 4°
- Apr 44° 24°
- May 59° 38°
- Jun 68° 49°
- Jul 70° 52°
- Aug 65° 47°
- Sep 53° 36°
- Oct 33° 20°
- Nov 15° 1°
- Dec 9° -5°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like in Delta Junction each month?
July is the warmest month, with normal highs of 70°F; January the coldest, with normal lows of −8°F. The most precipitation falls in July (2.37 in), the least in March (0.18 in).
Each month has its own page with the day-by-day normals, the month's records and its recent years:
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 6°F | −8°F | -1.0°F | 0.21 | 6 | <1 | 31 | 5 h 20 min |
| February | 16°F | −1°F | 7.3°F | 0.23 | 5 | <1 | 28 | 8 h 30 min |
| March | 25°F | 4°F | 14.2°F | 0.18 | 4 | <1 | 30 | 11 h 40 min |
| April | 44°F | 24°F | 33.9°F | 0.20 | 4 | <1 | 25 | 15 h |
| May | 59°F | 38°F | 48.5°F | 0.76 | 8 | <1 | 7 | 18 h 10 min |
| June | 68°F | 49°F | 58.5°F | 2.18 | 13 | <1 | <1 | 20 h 50 min |
| July | 70°F | 52°F | 60.7°F | 2.37 | 14 | <1 | <1 | 19 h 50 min |
| August | 65°F | 47°F | 55.6°F | 2.02 | 13 | <1 | 1 | 16 h 30 min |
| September | 53°F | 36°F | 44.8°F | 0.90 | 9 | <1 | 10 | 13 h 10 min |
| October | 33°F | 20°F | 26.5°F | 0.59 | 8 | <1 | 27 | 10 h |
| November | 15°F | 1°F | 8.2°F | 0.41 | 7 | <1 | 30 | 6 h 40 min |
| December | 9°F | −5°F | 2.4°F | 0.23 | 6 | <1 | 31 | 4 h 20 min |
| Year (annual) | 39°F | 21°F | 30.0°F | 10.28 | 96 | <1 | 219 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | −14°C | −22°C | −18.3°C | 5 mm |
| February | −9°C | −18°C | −13.7°C | 6 mm |
| March | −4°C | −16°C | −9.9°C | 5 mm |
| April | 7°C | −5°C | 1.1°C | 5 mm |
| May | 15°C | 3°C | 9.2°C | 19 mm |
| June | 20°C | 9°C | 14.7°C | 55 mm |
| July | 21°C | 11°C | 15.9°C | 60 mm |
| August | 18°C | 8°C | 13.1°C | 51 mm |
| September | 12°C | 2°C | 7.1°C | 23 mm |
| October | 1°C | −7°C | −3.1°C | 15 mm |
| November | −9°C | −17°C | −13.2°C | 10 mm |
| December | −13°C | −20°C | −16.4°C | 6 mm |
NOAA publishes no 1991-2020 snowfall normal for this station. Delta Junction's own co-op station Delta Junction (20 mi SE) does: 42 inches of snow in a normal year (see the other stations below).
Source: NOAA NCEI 1991-2020 monthly normals, station USW00026415; annual normals. Wet days: 0.01 inch or more; 90°F days and freezing nights: NOAA's day counts. Daylight: sunrise to sunset on the 15th, computed from the latitude.
When is the best weather to visit Delta Junction?
Normal highs sit between 65°F and 85°F in June and July. Of those, June has the fewest days with rain (13).
That is a measurement, not a recommendation: it counts the months whose normal afternoon high sits between 65°F and 85°F, where a light layer is enough by day.
Source: NOAA NCEI 1991-2020 monthly normals, station USW00026415.
When is the last frost in Delta Junction?
In Delta Junction, the last spring frost (32°F) comes after May 17 in half of years and after May 31 in one year in ten; the first autumn frost comes before September 7 in half of years and before August 23 in one year in ten.
Frost-free in half of yearsFrost in 1 to 9 years out of 10Frost most years
- Last spring frost, half of years after
- May 171 year in 10 after May 31; 9 in 10 after May 3
- First autumn frost, half of years before
- September 71 year in 10 before August 23; 9 in 10 before September 22
NOAA puts the median frost-free season at 113 days, and the season without a hard freeze (28°F) at 134 days.
A hard freeze (28°F) comes after May 6 in half of springs and before September 20 in half of autumns.
By the USDA's method, the average of each year's coldest night over 1991-2020, Delta Junction's NOAA station is in plant hardiness zone 2b: the coldest night of a typical year reaches −43°F (27 complete years).
Frost dates for every NOAA station in Alaska · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USW00026415; the station zone: ACIS daily lows, 1991-2020. A 10% date means one year in ten has a frost after it in spring or before it in autumn.
How hot and how cold does it get in Delta Junction?
In a normal year in Delta Junction, a 90°F day is rare, 219 nights fall to 32°F or colder and 96 days bring measurable precipitation.
- Days at 90°F or more
- fewer than 1a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 219a normal year
- Days that stay below freezing
- 151high of 32°F or less
- Days with 0.01 inch of precipitation
- 96a normal year
The highest temperature in Delta Junction's official record (kept by the National Weather Service since 1917) is 92°F, on June 15, 1969; the lowest is −63°F, on January 30, 1947.
The wettest calendar year on that record is 1975, with 17.77 in; the snowiest season is 1994–95, with 102.8 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USW00026415; records: ACIS (NOAA Regional Climate Centers), NWS threaded record BIGthr. Records use complete months only; a month missing more than three days is left out.
How humid and windy is Delta Junction, and how clear are its skies?
The summer (June-August) dew point averages 44°F. The muggiest month is July, with an average dew point of 47°F; the driest air comes in January (−5°F). December is the windiest month (12.2 mph on average), and March has the most clear or nearly clear hours (33%).
| Month | Dew point | Humidity | Afternoon humidity | Wind | Clear or few clouds | Overcast |
|---|---|---|---|---|---|---|
| January | −5°F | 73% | 70% | 11.8 mph | 29% | 34% |
| February | 1°F | 66% | 57% | 10.0 mph | 31% | 35% |
| March | 10°F | 56% | 43% | 9.2 mph | 33% | 34% |
| April | 23°F | 48% | 34% | 8.5 mph | 22% | 33% |
| May | 35°F | 49% | 35% | 8.0 mph | 10% | 34% |
| June | 46°F | 59% | 44% | 6.7 mph | 9% | 38% |
| July | 47°F | 64% | 50% | 7.1 mph | 9% | 45% |
| August | 39°F | 66% | 50% | 7.3 mph | 9% | 44% |
| September | 28°F | 69% | 57% | 8.5 mph | 12% | 50% |
| October | 11°F | 78% | 73% | 10.0 mph | 14% | 52% |
| November | −2°F | 75% | 74% | 11.8 mph | 23% | 40% |
| December | −4°F | 76% | 77% | 12.2 mph | 28% | 36% |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00026415. Monthly averages of all hours; afternoon humidity at 3 p.m. local standard time; sky as the share of hours NOAA's observations rate clear or few clouds (a dash where NOAA publishes no sky value).
How sunny is Delta Junction?
Over a year 67% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Delta Junction, 2.5 kWh per square metre a day. April is the sunniest month (78%) and October the cloudiest (55%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 60% | 0.2 |
| February | 61% | 0.8 |
| March | 73% | 2.4 |
| April | 78% | 4.4 |
| May | 72% | 5.3 |
| June | 65% | 5.3 |
| July | 63% | 4.7 |
| August | 64% | 3.7 |
| September | 61% | 2.3 |
| October | 55% | 1.0 |
| November | 56% | 0.3 |
| December | 65% | 0.1 |
Source: NASA POWER solar climatology, 2001-2020 (CERES SYN1deg). Satellite-based, for the 1-degree cell (about 100 km across) around the station, so it describes the area rather than the airport.
How much heating and cooling does Delta Junction need?
A normal year in Delta Junction brings 12,783 heating degree days, 2.4 times the median U.S. place (5,373), and 34 cooling degree days, 96% fewer than the median (908). Nine months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 882 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 2,044 | 0 |
| February | 1,614 | 0 |
| March | 1,576 | 0 |
| April | 935 | 0 |
| May | 513 | 0 |
| June | 209 | 12 |
| July | 149 | 15 |
| August | 297 | 6 |
| September | 605 | 0 |
| October | 1,195 | 0 |
| November | 1,705 | 0 |
| December | 1,941 | 0 |
| Year (annual) | 12,783 | 34 |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00026415. A degree day is one degree of a day's mean temperature below 65°F (heating) or above it (cooling); utilities use them to estimate energy use.
Has Delta Junction been warmer than normal lately?
2024 averaged 30.7°F, 0.7°F above the 1991-2020 normal of 30.0°F. 2 of the 4 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 28.2°F | −1.8°F | 9.85 |
| 2022 | 30.0°F | at normal | 8.16 |
| 2023 | 30.2°F | +0.2°F | 7.93 |
| 2024 | 30.7°F | +0.7°F | 9.42 |
Over 75 complete years from 1943 to 2025, the station's annual mean temperature rose at a fitted 6.5°F per century (+0.36°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USW00026415; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Delta Junction's climate compare?
Delta Junction is warmer than 35 of the other 84 places with their own NOAA record in Alaska, and wetter than 3. Across the 7,247 U.S. stations with normals, its annual mean of 30.0°F is warmer than 1%.
In the Köppen classification computed from these normals, Delta Junction is Dwc: continental, dry-winter, cool summer. What the classes mean.
Places with the most similar year elsewhere
Measured month by month on the normal high, low and precipitation, among places of 20,000 or more people in other states:
Source: NOAA NCEI 1991-2020 normals for every station PlainClimate covers. Similarity: the root-mean-square difference of the 36 monthly figures, precipitation weighted so an inch counts like 6°F.
Which places near Delta Junction share this climate record?
2 places have no NOAA station with 1991-2020 normals of their own, and this station is the nearest full record. A place's own climate can differ from these figures, by several degrees where it sits much higher or lower than the station, nearer the coast, or inside a large city's heat; for the larger places the next nearest records are named with their yearly mean, so the spread around them is visible, and places of 50,000 or more have their own page with NOAA's gridded normals.
- Deltana, AK2,064 people · 18 mi SE
- Fort Greely, AK85 people · 2 mi S
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
What do Delta Junction's other NOAA stations record?
One more NOAA station keeps 1991-2020 normals in or near Delta Junction. This page uses Big Delta Airport; the other differs by site and elevation:
| Station | From this station | Elevation | Year | Jan low | Jul high | Precip. | Snow | Last frost |
|---|---|---|---|---|---|---|---|---|
| Delta Junction (20 mi SE) USC00502352 | 19 mi E | 1,125 ft | 27.3°F | −13°F | 71°F | 11.8 | 42 | June 5 |
Source: NOAA NCEI 1991-2020 normals for each station. Last frost: the median last spring date of 32°F.
Questions about Delta Junction's climate
What is the coldest month in Delta Junction?
January, with a normal high of 6°F and a normal low of −8°F. The warmest is July (70°F by day, 52°F at night).
Does it snow in Delta Junction?
Yes. NOAA publishes no 1991-2020 snowfall normal for Delta Junction's NOAA station; Delta Junction's own co-op station Delta Junction (20 mi SE) records 42 inches of snow in a normal year.
What is the rainiest month in Delta Junction?
July, with 2.37 in of precipitation in a normal year; the driest is March with 0.18 in.
What plant hardiness zone is Delta Junction in?
By the same method at Delta Junction's NOAA station, the coldest night of a typical year reaches −43°F (27 years, 1991-2020): zone 2b.
How late can frost come in Delta Junction?
In half of years the last 32°F night comes after May 17; in one year in ten it comes after May 31. Waiting until May 31 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Delta Junction in OctoberThis month day by day, its records and recent years
- Alaska climateThe statewide normals and every place in the state
- Delta (5 mi NE), AK7 miles from this station, 27.4°F a year
- Delta (6 mi N), AK9 miles from this station, 25.9°F a year
- Whitestone, AK12 miles from this station, 29.6°F a year
- Dry Creek, AK40 miles from this station, 27.2°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made