Mackay, Idaho climate: Normal weather by month, frost dates and records
Mackay's normal year runs from 8°F January nights to 83°F July afternoons, with 9.9 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 5.7°C, January lows of −13°C, July highs of 29°C, 251 mm of precipitation a year.
- NOAA stationMackay Lost River Ranger Station
- Station IDUSC00105462
- Location43.92°N 113.62°W
- Elevation5,897 ft (1,797 m)
- Population480
On October 14, the normal high in Mackay is 59°F and the normal low 32°F, and the chance of measurable rain or snow is 16%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Mackay.
- Jan 30° 8°
- Feb 34° 12°
- Mar 44° 22°
- Apr 55° 29°
- May 65° 37°
- Jun 73° 43°
- Jul 83° 50°
- Aug 82° 48°
- Sep 72° 40°
- Oct 58° 31°
- Nov 41° 19°
- Dec 29° 10°
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 Mackay each month?
July is the warmest month, with normal highs of 83°F; January the coldest, with normal lows of 8°F. The most precipitation falls in June (1.45 in), the least in February (0.51 in).
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 30°F | 8°F | 19.0°F | 0.75 | 6 | <1 | 31 | 9 h 10 min |
| February | 34°F | 12°F | 23.3°F | 0.51 | 6 | <1 | 28 | 10 h 30 min |
| March | 44°F | 22°F | 32.9°F | 0.72 | 5 | <1 | 29 | 11 h 50 min |
| April | 55°F | 29°F | 41.8°F | 0.88 | 7 | <1 | 21 | 13 h 20 min |
| May | 65°F | 37°F | 50.8°F | 1.23 | 8 | <1 | 9 | 14 h 40 min |
| June | 73°F | 43°F | 58.0°F | 1.45 | 7 | 1 | 2 | 15 h 30 min |
| July | 83°F | 50°F | 66.6°F | 0.65 | 5 | 5 | <1 | 15 h 10 min |
| August | 82°F | 48°F | 64.7°F | 0.68 | 5 | 2 | <1 | 14 h |
| September | 72°F | 40°F | 56.3°F | 0.77 | 5 | <1 | 4 | 12 h 40 min |
| October | 58°F | 31°F | 44.2°F | 0.84 | 5 | <1 | 19 | 11 h 10 min |
| November | 41°F | 19°F | 30.2°F | 0.53 | 6 | <1 | 29 | 9 h 40 min |
| December | 29°F | 10°F | 19.2°F | 0.87 | 7 | <1 | 31 | 9 h |
| Year (annual) | 55°F | 29°F | 42.2°F | 9.88 | 71 | 7 | 202 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | −1°C | −13°C | −7.2°C | 19 mm |
| February | 1°C | −11°C | −4.8°C | 13 mm |
| March | 7°C | −6°C | 0.5°C | 18 mm |
| April | 13°C | −2°C | 5.4°C | 22 mm |
| May | 18°C | 3°C | 10.4°C | 31 mm |
| June | 23°C | 6°C | 14.4°C | 37 mm |
| July | 29°C | 10°C | 19.2°C | 17 mm |
| August | 28°C | 9°C | 18.2°C | 17 mm |
| September | 22°C | 5°C | 13.5°C | 20 mm |
| October | 14°C | −1°C | 6.8°C | 21 mm |
| November | 5°C | −7°C | −1.0°C | 13 mm |
| December | −2°C | −12°C | −7.1°C | 22 mm |
NOAA publishes no 1991-2020 snowfall normal for this station. The nearest record that keeps one, Chilly Barton Flat (11 miles away), gets 18 inches of snow in a normal year; elevation and distance can change that.
Source: NOAA NCEI 1991-2020 monthly normals, station USC00105462; 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 Mackay?
Normal highs sit between 65°F and 85°F in June, July, August and September. Of those, July has the fewest days with rain (5).
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 USC00105462.
When is the last frost in Mackay?
In Mackay, the last spring frost (32°F) comes after June 1 in half of years and after June 21 in one year in ten; the first autumn frost comes before September 20 in half of years and before September 4 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
- June 11 year in 10 after June 21; 9 in 10 after May 13
- First autumn frost, half of years before
- September 201 year in 10 before September 4; 9 in 10 before October 3
NOAA puts the median frost-free season at 109 days, and the season without a hard freeze (28°F) at 138 days.
A hard freeze (28°F) comes after May 13 in half of springs and before October 1 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Mackay in zone 5a in ZIP code 83255, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Mackay's NOAA station is in zone 5b: the coldest night of a typical year reaches −14°F (20 complete years); the map interpolates between stations and terrain, so the station and the ZIP area can differ by half a zone.
Frost dates for every NOAA station in Idaho · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00105462; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; 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 Mackay?
In a normal year in Mackay, 7 days a year reach 90°F, 202 nights fall to 32°F or colder and 71 days bring measurable precipitation.
- Days at 90°F or more
- 7a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 202a normal year
- Days that stay below freezing
- 59high of 32°F or less
- Days with 0.01 inch of precipitation
- 71a normal year
The highest temperature in this station's record (since 1908) is 104°F, on July 27, 1939; the lowest is −33°F, on February 4, 1985.
The wettest calendar year on that record is 1938, with 14.96 in; the snowiest season is 1951–52, with 89.4 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00105462; records: ACIS (NOAA Regional Climate Centers), station USC00105462. Records use complete months only; a month missing more than three days is left out.
How sunny is Mackay?
Over a year 79% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Mackay, 4.5 kWh per square metre a day. July is the sunniest month (89%) and December the cloudiest (64%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 68% | 1.9 |
| February | 70% | 2.8 |
| March | 71% | 4.0 |
| April | 73% | 5.4 |
| May | 77% | 6.5 |
| June | 83% | 7.5 |
| July | 89% | 7.6 |
| August | 88% | 6.5 |
| September | 86% | 5.2 |
| October | 81% | 3.5 |
| November | 73% | 2.2 |
| December | 64% | 1.5 |
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 Mackay need?
A normal year in Mackay brings 8,438 heating degree days, 57% more than the median U.S. place (5,373), and 171 cooling degree days, 81% fewer than the median (908). Eight months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 1,593 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,426 | 0 |
| February | 1,168 | 0 |
| March | 997 | 0 |
| April | 698 | 0 |
| May | 441 | 1 |
| June | 223 | 13 |
| July | 47 | 95 |
| August | 67 | 58 |
| September | 267 | 5 |
| October | 643 | 0 |
| November | 1,044 | 0 |
| December | 1,418 | 0 |
| Year (annual) | 8,438 | 171 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00105462. 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 Mackay been warmer than normal lately?
2023 averaged 43.5°F, 1.3°F above the 1991-2020 normal of 42.2°F.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2023 | 43.5°F | +1.3°F | 14.63 |
Over 30 complete years from 1950 to 2024, the station's annual mean temperature rose at a fitted 3.9°F per century (+0.21°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00105462; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does Mackay's climate compare?
Mackay is warmer than 9 of the other 84 places with their own NOAA record in Idaho, and wetter than 10. Across the 7,247 U.S. stations with normals, its annual mean of 42.2°F is warmer than 10%.
In the Köppen classification computed from these normals, Mackay is BSk: cold semi-arid steppe. 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 Mackay share this climate record?
Lost River has no NOAA station with 1991-2020 normals of its 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.
- Lost River, ID51 people · 16 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.
Questions about Mackay's climate
What is the coldest month in Mackay?
January, with a normal high of 30°F and a normal low of 8°F. The warmest is July (83°F by day, 50°F at night).
Does it snow in Mackay?
Yes. NOAA publishes no 1991-2020 snowfall normal for Mackay's NOAA station; the nearest record that keeps one, Chilly Barton Flat (11 miles away), records 18 inches of snow in a normal year.
What is the rainiest month in Mackay?
June, with 1.45 in of precipitation in a normal year; the driest is February with 0.51 in.
What plant hardiness zone is Mackay in?
The USDA's 2023 map puts Mackay in zone 5a in ZIP code 83255, the nearest ZIP area. By the same method at Mackay's NOAA station, the coldest night of a typical year reaches −14°F (20 years, 1991-2020): zone 5b.
How late can frost come in Mackay?
In half of years the last 32°F night comes after June 1; in one year in ten it comes after June 21. Waiting until June 21 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Idaho climateThe statewide normals and every place in the state
- Chilly Barton Flat, ID11 miles from this station, 41.0°F a year
- Arco, ID25 miles from this station, 43.7°F a year
- Craters Of The Moon, ID32 miles from this station, 39.1°F a year
- Howe, ID32 miles from this station, 44.0°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made