Massacre Rocks State Park, Idaho climate: Climate normals at a NOAA weather station
Massacre Rocks State Park's normal year runs from 17°F January nights to 89°F July afternoons, with 13.5 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 8.5°C, January lows of −8°C, July highs of 32°C, 343 mm of precipitation a year.
- NOAA stationMassacre Rocks State Park
- Station IDUSC00105678
- Location42.67°N 113.00°W
- Elevation4,195 ft (1,279 m)
On October 23, the normal high in Massacre Rocks State Park is 59°F and the normal low 32°F, and the chance of measurable rain or snow is 24%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Massacre Rocks State Park.
- Jan 35° 17°
- Feb 39° 21°
- Mar 51° 27°
- Apr 59° 33°
- May 68° 39°
- Jun 78° 46°
- Jul 89° 53°
- Aug 88° 52°
- Sep 77° 43°
- Oct 62° 34°
- Nov 47° 24°
- Dec 35° 18°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like at Massacre Rocks State Park each month?
July is the warmest month, with normal highs of 89°F; January the coldest, with normal lows of 17°F. The most precipitation falls in April (1.62 in), the least in July (0.45 in).
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 35°F | 17°F | 26.0°F | 1.48 | 10 | <1 | 29 | 9 h 20 min |
| February | 39°F | 21°F | 30.1°F | 1.05 | 9 | <1 | 25 | 10 h 30 min |
| March | 51°F | 27°F | 39.2°F | 1.32 | 9 | <1 | 23 | 11 h 50 min |
| April | 59°F | 33°F | 45.7°F | 1.62 | 10 | <1 | 13 | 13 h 20 min |
| May | 68°F | 39°F | 53.7°F | 1.56 | 11 | 1 | 4 | 14 h 40 min |
| June | 78°F | 46°F | 62.1°F | 1.00 | 7 | 6 | <1 | 15 h 20 min |
| July | 89°F | 53°F | 70.9°F | 0.45 | 4 | 19 | <1 | 15 h |
| August | 88°F | 52°F | 70.0°F | 0.58 | 6 | 18 | <1 | 14 h |
| September | 77°F | 43°F | 60.1°F | 0.88 | 6 | 5 | 2 | 12 h 30 min |
| October | 62°F | 34°F | 48.0°F | 1.07 | 8 | <1 | 13 | 11 h 10 min |
| November | 47°F | 24°F | 35.4°F | 1.13 | 8 | <1 | 23 | 9 h 50 min |
| December | 35°F | 18°F | 26.3°F | 1.35 | 10 | <1 | 28 | 9 h |
| Year (annual) | 61°F | 34°F | 47.3°F | 13.49 | 97 | 49 | 160 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | 2°C | −8°C | −3.3°C | 38 mm |
| February | 4°C | −6°C | −1.1°C | 27 mm |
| March | 11°C | −3°C | 4.0°C | 34 mm |
| April | 15°C | 0°C | 7.6°C | 41 mm |
| May | 20°C | 4°C | 12.1°C | 40 mm |
| June | 26°C | 8°C | 16.7°C | 25 mm |
| July | 32°C | 12°C | 21.6°C | 11 mm |
| August | 31°C | 11°C | 21.1°C | 15 mm |
| September | 25°C | 6°C | 15.6°C | 22 mm |
| October | 17°C | 1°C | 8.9°C | 27 mm |
| November | 8°C | −4°C | 1.9°C | 29 mm |
| December | 2°C | −8°C | −3.2°C | 34 mm |
NOAA publishes no 1991-2020 snowfall normal for this station. The nearest record that keeps one, American Falls (6 mi NE) (14 miles away), gets 35 inches of snow in a normal year; elevation and distance can change that.
Source: NOAA NCEI 1991-2020 monthly normals, station USC00105678; 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.
Which months are mildest at Massacre Rocks State Park?
Normal highs sit between 65°F and 85°F in May, June and September. Of those, September has the fewest days with rain (6).
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 USC00105678.
When is the last frost at Massacre Rocks State Park?
In Massacre Rocks State Park, the last spring frost (32°F) comes after May 20 in half of years and after June 9 in one year in ten; the first autumn frost comes before September 26 in half of years and before September 8 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 201 year in 10 after June 9; 9 in 10 after May 4
- First autumn frost, half of years before
- September 261 year in 10 before September 8; 9 in 10 before October 11
NOAA puts the median frost-free season at 125 days, and the season without a hard freeze (28°F) at 157 days.
A hard freeze (28°F) comes after May 4 in half of springs and before October 9 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Massacre Rocks State Park in zone 6a in ZIP code 83211, the nearest ZIP area.
Frost dates for every NOAA station in Idaho · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00105678; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026. 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 at Massacre Rocks State Park?
In a normal year in Massacre Rocks State Park, 49 days a year reach 90°F (5 of them 100°F or more), 160 nights fall to 32°F or colder and 97 days bring measurable precipitation.
- Days at 90°F or more
- 49a normal year
- Days at 100°F or more
- 5a normal year
- Nights at 32°F or colder
- 160a normal year
- Days that stay below freezing
- 25high of 32°F or less
- Days with 0.01 inch of precipitation
- 97a normal year
Source: NOAA NCEI 1991-2020 annual normals, station USC00105678.
How sunny is it at Massacre Rocks State Park?
Over a year 78% of the sunlight that would reach the ground under clear skies gets through the clouds at Massacre Rocks State Park, 4.5 kWh per square metre a day. July is the sunniest month (88%) and December the cloudiest (60%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 67% | 1.9 |
| February | 68% | 2.8 |
| March | 71% | 4.0 |
| April | 72% | 5.3 |
| May | 77% | 6.5 |
| June | 84% | 7.5 |
| July | 88% | 7.5 |
| August | 88% | 6.6 |
| September | 85% | 5.2 |
| October | 79% | 3.5 |
| November | 69% | 2.1 |
| December | 60% | 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 many heating and cooling degree days does Massacre Rocks State Park record?
A normal year at Massacre Rocks State Park brings 6,900 heating degree days, 28% more than the median U.S. place (5,373), and 471 cooling degree days, 48% 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 2,236 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,207 | 0 |
| February | 977 | 0 |
| March | 801 | 0 |
| April | 581 | 0 |
| May | 357 | 5 |
| June | 136 | 51 |
| July | 18 | 201 |
| August | 24 | 177 |
| September | 182 | 35 |
| October | 529 | 2 |
| November | 888 | 0 |
| December | 1,200 | 0 |
| Year (annual) | 6,900 | 471 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00105678. 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.
Have recent years at Massacre Rocks State Park been warmer than normal?
2025 averaged 51.5°F, 4.2°F above the 1991-2020 normal of 47.3°F. 3 of the 4 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 49.4°F | +2.1°F | 12.38 |
| 2022 | 46.0°F | −1.3°F | – |
| 2024 | 50.5°F | +3.2°F | 17.49 |
| 2025 | 51.5°F | +4.2°F | 11.08 |
Source: observed years: ACIS, station USC00105678. A year counts only with all twelve months complete.
How does Massacre Rocks State Park's climate compare?
Massacre Rocks State Park is warmer than 52 of the 85 places with their own NOAA record in Idaho, and wetter than 39. Across the 7,247 U.S. stations with normals, its annual mean of 47.3°F is warmer than 29%.
In the Köppen classification computed from these normals, Massacre Rocks State Park is Dsb: continental, dry-summer, warm 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 Massacre Rocks State Park share this climate record?
Rockland 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.
- Rockland, ID263 people · 9 mi SE
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 Massacre Rocks State Park's climate
What is the coldest month at Massacre Rocks State Park?
January, with a normal high of 35°F and a normal low of 17°F. The warmest is July (89°F by day, 53°F at night).
Does it snow at Massacre Rocks State Park?
Yes. NOAA publishes no 1991-2020 snowfall normal for the station; the nearest record that keeps one, American Falls (6 mi NE) (14 miles away), records 35 inches of snow in a normal year.
What is the rainiest month at Massacre Rocks State Park?
April, with 1.62 in of precipitation in a normal year; the driest is July with 0.45 in.
What plant hardiness zone is Massacre Rocks State Park in?
The USDA's 2023 map puts Massacre Rocks State Park in zone 6a in ZIP code 83211, the nearest ZIP area.
How late can frost come at Massacre Rocks State Park?
In half of years the last 32°F night comes after May 20; in one year in ten it comes after June 9. Waiting until June 9 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Idaho climateThe statewide normals and every place in the state
- American Falls, ID14 miles from this station, 48.7°F a year
- Aberdeen, ID22 miles from this station, 45.4°F a year
- Minidoka, ID25 miles from this station, 48.6°F a year
- Pocatello, ID28 miles from this station, 47.0°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made