Gross Reservoir, Colorado climate: Climate normals at a NOAA weather station
Gross Reservoir's normal year runs from 17°F January nights to 79°F July afternoons, with 20.3 inches of precipitation and 99 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 6.6°C, January lows of −8°C, July highs of 26°C, 515 mm of precipitation a year.
- NOAA stationGross Reservoir
- Station IDUSC00053629
- Location39.94°N 105.35°W
- Elevation7,970 ft (2,429 m)
On October 23, the normal high in Gross Reservoir is 54°F and the normal low 29°F, and the chance of measurable rain or snow is 18%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Gross Reservoir.
- Jan 39° 17°
- Feb 40° 17°
- Mar 47° 22°
- Apr 52° 27°
- May 61° 35°
- Jun 73° 44°
- Jul 79° 50°
- Aug 77° 48°
- Sep 70° 41°
- Oct 57° 31°
- Nov 47° 24°
- Dec 40° 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 Gross Reservoir each month?
July is the warmest month, with normal highs of 79°F; January the coldest, with normal lows of 17°F. The most precipitation falls in May (2.89 in), the least in January (0.71 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 39°F | 17°F | 28.1°F | 0.71 | 9.4 | 5 | <1 | 29 | 9 h 40 min |
| February | 40°F | 17°F | 28.2°F | 0.90 | 14.0 | 6 | <1 | 27 | 10 h 40 min |
| March | 47°F | 22°F | 34.7°F | 1.94 | 21.0 | 6 | <1 | 28 | 11 h 50 min |
| April | 52°F | 27°F | 39.7°F | 2.73 | 19.8 | 8 | <1 | 24 | 13 h 10 min |
| May | 61°F | 35°F | 48.1°F | 2.89 | 3.9 | 11 | <1 | 10 | 14 h 20 min |
| June | 73°F | 44°F | 58.1°F | 1.87 | 0.1 | 8 | 1 | <1 | 15 h |
| July | 79°F | 50°F | 64.5°F | 2.04 | 0.0 | 10 | 1 | <1 | 14 h 50 min |
| August | 77°F | 48°F | 62.3°F | 2.12 | 0.0 | 11 | <1 | <1 | 13 h 50 min |
| September | 70°F | 41°F | 55.2°F | 1.99 | 0.9 | 7 | <1 | 2 | 12 h 30 min |
| October | 57°F | 31°F | 44.1°F | 1.35 | 6.9 | 6 | <1 | 16 | 11 h 10 min |
| November | 47°F | 24°F | 35.3°F | 0.96 | 12.0 | 5 | <1 | 25 | 10 h |
| December | 40°F | 18°F | 28.5°F | 0.78 | 11.1 | 5 | <1 | 29 | 9 h 20 min |
| Year (annual) | 57°F | 31°F | 43.9°F | 20.28 | 99.1 | 88 | 3 | 188 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | 4°C | −8°C | −2.2°C | 18 mm | 24 cm |
| February | 4°C | −8°C | −2.1°C | 23 mm | 36 cm |
| March | 8°C | −5°C | 1.5°C | 49 mm | 53 cm |
| April | 11°C | −3°C | 4.3°C | 69 mm | 50 cm |
| May | 16°C | 2°C | 8.9°C | 73 mm | 10 cm |
| June | 23°C | 6°C | 14.5°C | 47 mm | 0 cm |
| July | 26°C | 10°C | 18.1°C | 52 mm | 0 cm |
| August | 25°C | 9°C | 16.8°C | 54 mm | 0 cm |
| September | 21°C | 5°C | 12.9°C | 51 mm | 2 cm |
| October | 14°C | 0°C | 6.7°C | 34 mm | 18 cm |
| November | 8°C | −5°C | 1.8°C | 24 mm | 30 cm |
| December | 4°C | −8°C | −1.9°C | 20 mm | 28 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00053629; 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 Gross Reservoir?
Normal highs sit between 65°F and 85°F in June, July, August and September. Of those, September has the fewest days with rain (7).
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 USC00053629.
When is the last frost at Gross Reservoir?
In Gross Reservoir, the last spring frost (32°F) comes after May 24 in half of years and after June 10 in one year in ten; the first autumn frost comes before September 23 in half of years and before September 9 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 241 year in 10 after June 10; 9 in 10 after May 11
- First autumn frost, half of years before
- September 231 year in 10 before September 9; 9 in 10 before October 6
NOAA puts the median frost-free season at 120 days, and the season without a hard freeze (28°F) at 143 days.
A hard freeze (28°F) comes after May 10 in half of springs and before October 3 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Gross Reservoir in zone 6a in ZIP code 80025, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, the station is in zone 5b: the coldest night of a typical year reaches −12°F (18 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 Colorado · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00053629; 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 at Gross Reservoir?
In a normal year in Gross Reservoir, 3 days a year reach 90°F, 188 nights fall to 32°F or colder and 88 days bring measurable precipitation.
- Days at 90°F or more
- 3a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 188a normal year
- Days that stay below freezing
- 29high of 32°F or less
- Days with 0.01 inch of precipitation
- 88a normal year
- Days with 1 inch of snow or more
- 28a normal year
Source: NOAA NCEI 1991-2020 annual normals, station USC00053629.
How sunny is it at Gross Reservoir?
Over a year 77% of the sunlight that would reach the ground under clear skies gets through the clouds at Gross Reservoir, 4.7 kWh per square metre a day. February is the sunniest month (82%) and May the cloudiest (71%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 81% | 2.7 |
| February | 82% | 3.8 |
| March | 79% | 4.9 |
| April | 73% | 5.6 |
| May | 71% | 6.2 |
| June | 78% | 7.0 |
| July | 75% | 6.4 |
| August | 75% | 5.8 |
| September | 81% | 5.2 |
| October | 80% | 3.9 |
| November | 79% | 2.8 |
| December | 79% | 2.4 |
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 Gross Reservoir record?
A normal year at Gross Reservoir brings 7,765 heating degree days, 45% more than the median U.S. place (5,373), and 90 cooling degree days, 90% 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 1,402 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,144 | 0 |
| February | 1,030 | 0 |
| March | 941 | 0 |
| April | 761 | 0 |
| May | 524 | 0 |
| June | 219 | 12 |
| July | 64 | 47 |
| August | 110 | 28 |
| September | 299 | 4 |
| October | 650 | 0 |
| November | 893 | 0 |
| December | 1,131 | 0 |
| Year (annual) | 7,765 | 90 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00053629. 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 Gross Reservoir been warmer than normal?
2024 averaged 45.9°F, 2.0°F above the 1991-2020 normal of 43.9°F. 2 of the 2 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 45.5°F | +1.6°F | 18.93 | 67.7 |
| 2024 | 45.9°F | +2.0°F | 19.71 | 108.4 |
Source: observed years: ACIS, station USC00053629. A year counts only with all twelve months complete.
How does Gross Reservoir's climate compare?
Gross Reservoir is warmer than 35 of the 125 places with their own NOAA record in Colorado, and wetter than 109. Across the 7,247 U.S. stations with normals, its annual mean of 43.9°F is warmer than 15%.
In the Köppen classification computed from these normals, Gross Reservoir is Dfb: continental, no dry season, 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 Gross Reservoir share this climate record?
5 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.
- St. Ann Highlands, CO483 people · 7 mi NW
- Sugarloaf, CO442 people · 6 mi NW
- Gold Hill, CO288 people · 9 mi NW
- Mountain Meadows, CO205 people · 7 mi N
- Bonanza Mountain Estates, CO132 people · 7 mi W
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 Gross Reservoir's climate
What is the coldest month at Gross Reservoir?
January, with a normal high of 39°F and a normal low of 17°F. The warmest is July (79°F by day, 50°F at night).
Does it snow at Gross Reservoir?
Yes: 99 inches in a normal year, falling on 30 days with 0.1 inch or more, the most in March (21.0 inches).
What is the rainiest month at Gross Reservoir?
May, with 2.89 in of precipitation in a normal year; the driest is January with 0.71 in.
What plant hardiness zone is Gross Reservoir in?
The USDA's 2023 map puts Gross Reservoir in zone 6a in ZIP code 80025, the nearest ZIP area. By the same method at the station, the coldest night of a typical year reaches −12°F (18 years, 1991-2020): zone 5b.
How late can frost come at Gross Reservoir?
In half of years the last 32°F night comes after May 24; in one year in ten it comes after June 10. Waiting until June 10 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Colorado climateThe statewide normals and every place in the state
- Coal Creek, CO3 miles from this station, 39.9°F a year
- Boulder, CO6 miles from this station, 51.5°F a year
- Ralston Reservoir, CO9 miles from this station, 51.5°F a year
- Wheat Ridge, CO17 miles from this station, 50.3°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made