No extremes in Greenhorn: its weather tracks the middle of U.S. towns
In January the night’s low is typically 25°. From frosty January to warm July, readings climb 62°. It is a dry place: less rain and snow fall here than on 62% of U.S. towns. Seedlings are safe outdoors from about June 11, with the first autumn frost due around September 10.
A year in Greenhorn at a glance
Each month’s typical high and low, and what it brings.
What stands out about Greenhorn’s climate
Compared with towns across the U.S., with Greenhorn’s place in California beside it.
What a year in Greenhorn feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 91 frost-free days a year
In half of years the last 32° night comes by June 11 and the first by September 10. Frost and day counts come from NOAA’s station at Portola, CA, 17 miles from the town’s center, 350 ft higher.
The 2023 USDA map puts Greenhorn’s center in zone 7a: the coldest night of a typical winter, averaged over 1991–2020, reaches about 5°. Plant labels use the zone; frost dates tell you when to plant.
Freezing nights by month
Average nights at or below 32°
90° days by month
Average days at 90° or more
About 28 inches of snow a winter
Snow, measured at Quincy, CA, falls mostly in February. Precipitation (rain plus melted snow) adds up to 40 inches a year; December is the wettest month and July the driest. Rain or snow falls on about 84 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Greenhorn
98% of the work is heating, so the furnace matters far more than the air conditioner. Months averaging under 55° run from October through May.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Portola, CA.
Living with Greenhorn’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
91 frost-free days in zone 7a. The last frost comes by Jun 11 in half of years, so many gardeners wait a week or two past that to set out tomatoes. The first fall frost comes by Sep 10.
Months with highs of 62–84° and lows of 40° or more: June and September. 13 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Greenhorn from natural hazards, wildfire is the largest share (47%). Normals are averages; the hazards page covers the extremes.
Natural hazards →Greenhorn and similar climates
TownRatings has no climate map of the towns around Greenhorn yet.
Climates most like Greenhorn’s, farther away
TownRatings’ own comparison of NOAA 1991–2020 normals, not a NOAA product: places of 5,000+ at least 150 miles away, one per state, closest on January low, July high, precipitation and snow.
| Town | Jan. low | July high | Precip. | Snow |
|---|---|---|---|---|
| Greenhorn, CA | 25° | 87° | 40" | 28" |
| Halfway, MD | 23° | 87° | 40" | 31" |
| Woodstock, VA | 23° | 87° | 39" | 24" |
| Martinsburg, WV | 23° | 87° | 40" | 23" |
| Chambersburg, PA | 22° | 86° | 43" | 31" |
Temperatures and precipitation come from NOAA’s 5 km grid; snow and day counts from the stations named on this page.
Warmer than it used to be
The last 30 years in Greenhorn averaged 1.1° warmer than the 1900s. The biggest change is in September (+2.2°).
A smaller shift than in 71% of U.S. towns.
Change by month
The two periods overlap (1991–2000 is in both), which makes the gap a little smaller than it would be between separate periods.
How Greenhorn compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Greenhorn’s place among California’s.
Greenhorn weather by month
Highs, lows and precipitation from NOAA’s grid at Greenhorn’s center; snow, wet days and snow on the ground from Quincy, CA. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 44° | 25° | 7.0" | 5.8" | 12 | 3 | 27° – 40° |
| February | 48° | 26° | 6.4" | 7.6" | 11 | 2 | 30° – 43° |
| March | 53° | 29° | 5.8" | 5.4" | 13 | 1 | 34° – 47° |
| April | 59° | 32° | 3.2" | 1.6" | 9 | 0 | 40° – 49° |
| May | 69° | 39° | 2.1" | 0.0" | 7 | 0 | 46° – 61° |
| June | 78° | 44° | 0.8" | 0.0" | 3 | 0 | 57° – 67° |
| July | 87° | 50° | 0.1" | 0.0" | 1 | 0 | 64° – 72° |
| August | 86° | 48° | 0.2" | 0.0" | 1 | 0 | 64° – 71° |
| September | 80° | 42° | 0.5" | 0.0" | 2 | 0 | 58° – 65° |
| October | 68° | 35° | 2.2" | 0.1" | 5 | 0 | 46° – 55° |
| November | 52° | 29° | 4.0" | 1.7" | 8 | 0 | 33° – 46° |
| December | 43° | 25° | 7.2" | 6.2" | 12 | 1 | 30° – 38° |
| Year | 64° | 35° | 39.5" | 28.4" | 84 | 7 |
How much a month can swing
A normal is an average. May swings the most: from 1991 to 2020 its average ranged from 46° to 61°. September is the most reliable, staying within 7°.
Where Greenhorn’s numbers come from
Normals are 30-year averages, not a forecast. How TownRatings reads climate data →
- Temperatures and precipitation: NOAA’s gridded 1991–2020 normals for the 5 km cell at Greenhorn’s center.
- Snow: Quincy, CA.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Portola, CA, 17 miles from the town’s center, 350 ft higher; the nearest station that passes our checks for distance, height and agreement with the grid.
- Growing zone: USDA Plant Hardiness Zone Map, 2023. USDA Agricultural Research Service and PRISM Group, Oregon State University, prism.oregonstate.edu/phzm, accessed 8 Oct 2026.
- Then and now: NOAA’s gridded normals for 1901–2000 at the same cell.
- Storms and extremes: FEMA National Risk Index (expected annual losses to buildings).
Common questions about Greenhorn’s climate
What is the weather like in Greenhorn?
A typical July afternoon reaches 87°, a January night drops to 25°, and about 28 inches of snow falls in a normal winter. Milder January nights than 62% of U.S. towns; hotter July afternoons than 62% of U.S. towns.
How cold does it get in Greenhorn in winter?
December nights average 25°. About 205 nights a year reach 32° or below and 2 reach 0° or below. In the coldest December of the last 30 years the month averaged 30°.
How much snow does Greenhorn get?
About 28 inches in a normal winter at Quincy, CA, most of it in February, with snow on the ground about 7 days a year.
How hot does it get in Greenhorn?
July, with a typical high of 87° and a low of 50°. About 22 days a year reach 90° (Portola, CA).
When is the first and last frost in Greenhorn?
In half of years the last spring frost (32°) comes by June 11 and the first fall frost by September 10, about 91 frost-free days, at Portola, CA.
What growing zone is Greenhorn in?
Zone 7a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about 5°.
What is the best time of year to visit Greenhorn?
By one simple rule (highs of 62–84° and lows of 40° or more), June and September. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Greenhorn getting warmer?
Yes: 1991–2020 averaged 1.1° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 71% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Greenhorn.
Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000; USDA/PRISM 2023 hardiness zones; FEMA National Risk Index. Today’s forecast: National Weather Service.