Photo: Benjamin Cody · CC BY-SA 3.0O'Brien reaches 100° on about 19 days a year, more than 95% of U.S. towns
January nights here settle around 33°. Precipitation is plentiful here, more than falls on almost every U.S. town. Decade by decade the climate has edged up, 1.6° above 1901–2000. The heating season runs November to April: each of those months averages under 50°.
A year in O'Brien at a glance
Each month’s typical high and low, and what it brings.
What stands out about O'Brien’s climate
Compared with towns across the U.S., with O'Brien’s place in Oregon beside it.
What a year in O'Brien feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 161 frost-free days a year
In half of years the last 32° night comes by May 1 and the first by October 12. Frost and day counts come from NOAA’s station at Cave Junction 1 Wnw, OR, 6 miles from the town’s center, at about the same height.
The 2023 USDA map puts O'Brien’s center in zone 8b: the coldest night of a typical winter, averaged over 1991–2020, reaches about 15°. 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 7 inches of snow a winter
Snow, measured at Cave Junction 1 Wnw, OR, falls mostly in January and December. Precipitation (rain plus melted snow) adds up to 63 inches a year; December is the wettest month and July the driest. Rain or snow falls on about 119 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in O'Brien
87% of the work is heating, so the furnace matters far more than the air conditioner. Months averaging under 55° run from October through April.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Cave Junction 1 Wnw, OR.
Living with O'Brien’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
161 frost-free days in zone 8b. The last frost comes by May 1 in half of years, so many gardeners wait a week or two past that to set out tomatoes. The first fall frost comes by Oct 12.
Months with highs of 62–84° and lows of 40° or more: May, June and September. 4.2 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in O'Brien from natural hazards, river flooding is the largest share (38%); heat waves, cold waves, winter storms and ice storms together are 3%. Normals are averages; the hazards page covers the extremes.
Natural hazards →O'Brien and similar climates
TownRatings has no climate map of the towns around O'Brien yet.
Climates most like O'Brien’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 |
|---|---|---|---|---|
| O'Brien, OR | 33° | 89° | 63" | 7.1" |
| Dunlap, TN | 30° | 89° | 60" | 3.1" |
| Dahlonega, GA | 30° | 87° | 63" | 3.3" |
| Travelers Rest, SC | 32° | 88° | 60" | 1.9" |
| Mena, AR | 29° | 90° | 58" | 4.0" |
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 O'Brien averaged 1.6° warmer than the 1900s. The biggest change is in January (+2.8°).
A bigger shift than in 68% 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 O'Brien compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with O'Brien’s place among Oregon’s.
O'Brien weather by month
Highs, lows and precipitation from NOAA’s grid at O'Brien’s center; snow, wet days and snow on the ground from Cave Junction 1 Wnw, OR. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 49° | 33° | 11.2" | 2.1" | 17 | 2 | 36° – 47° |
| February | 53° | 33° | 8.5" | 1.2" | 14 | 1 | 36° – 49° |
| March | 58° | 34° | 8.2" | 1.5" | 16 | 0 | 41° – 51° |
| April | 63° | 37° | 4.7" | 0.2" | 13 | 0 | 46° – 54° |
| May | 72° | 42° | 2.3" | 0.0" | 8 | 0 | 51° – 64° |
| June | 80° | 47° | 1.0" | 0.0" | 4 | 0 | 59° – 70° |
| July | 89° | 52° | 0.2" | 0.0" | 1 | 0 | 64° – 74° |
| August | 89° | 50° | 0.3" | 0.0" | 1 | 0 | 66° – 74° |
| September | 83° | 45° | 0.9" | 0.0" | 3 | 0 | 60° – 68° |
| October | 69° | 39° | 3.7" | 0.0" | 7 | 0 | 51° – 59° |
| November | 54° | 36° | 8.5" | 0.2" | 16 | 0 | 38° – 50° |
| December | 47° | 33° | 13.5" | 1.9" | 19 | 0 | 36° – 44° |
| Year | 67° | 40° | 63.0" | 7.1" | 119 | 3 |
How much a month can swing
A normal is an average. May swings the most: from 1991 to 2020 its average ranged from 51° to 64°. December is the most reliable, staying within 7°.
Where O'Brien’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 O'Brien’s center.
- Snow: Cave Junction 1 Wnw, OR.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Cave Junction 1 Wnw, OR, 6 miles from the town’s center, at about the same height; 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 O'Brien’s climate
What is the weather like in O'Brien?
A typical July afternoon reaches 89°, a January night drops to 33°, and about 7 inches of snow falls in a normal winter. Milder January nights than 77% of U.S. towns; hotter July afternoons than 74% of U.S. towns.
How cold does it get in O'Brien in winter?
December nights average 33°. About 75 nights a year reach 32° or below. In the coldest December of the last 30 years the month averaged 36°.
How much snow does O'Brien get?
About 7.1 inches in a normal winter at Cave Junction 1 Wnw, OR, most of it in January and December, with snow on the ground about 3 days a year.
How hot does it get in O'Brien?
July, with a typical high of 89° and a low of 52°. About 73 days a year reach 90° and 19 reach 100° (Cave Junction 1 Wnw, OR).
When is the first and last frost in O'Brien?
In half of years the last spring frost (32°) comes by May 1 and the first fall frost by October 12, about 161 frost-free days, at Cave Junction 1 Wnw, OR.
What growing zone is O'Brien in?
Zone 8b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about 15°.
What is the best time of year to visit O'Brien?
By one simple rule (highs of 62–84° and lows of 40° or more), May, June and September. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is O'Brien getting warmer?
Yes: 1991–2020 averaged 1.6° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 68% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in O'Brien.
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.