Photo: M.O. Stevens · CC BY-SA 3.0July in Cornelius stays fresher than in 87% of U.S. towns
On a normal January night the air cools to about 35°. Rain follows the seasons: December brings about 23 times as much as July. In January, nights here are milder than in 81% of U.S. towns. The heating season runs November to March: each of those months averages under 50°.
A year in Cornelius at a glance
Each month’s typical high and low, and what it brings.
What stands out about Cornelius’ climate
Compared with towns across the U.S., with Cornelius’ place in Oregon beside it.
What a year in Cornelius feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 192 frost-free days a year
In half of years the last 32° night comes by April 16 and the first by October 26. Frost and day counts come from NOAA’s station at Forest Grove, OR, 2.5 miles from the town’s center, at about the same height.
The 2023 USDA map puts Cornelius’ center in zone 8b: the coldest night of a typical winter, averaged over 1991–2020, reaches about 18°. 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 5 inches of snow a winter
Snow, measured at Dilley 2 S, OR, falls mostly in January, February and December. Precipitation (rain plus melted snow) adds up to 44 inches a year; December is the wettest month and July the driest. Rain or snow falls on about 152 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Cornelius
94% 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 Forest Grove, OR.
Living with Cornelius’ climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
192 frost-free days in zone 8b. The last frost comes by Apr 16 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 26.
Months with highs of 62–84° and lows of 40° or more: May, June, July, August, September and October. 1.0 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Cornelius from natural hazards, earthquakes are the largest share (54%); heat waves, cold waves, winter storms and ice storms together are 12%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Cornelius and similar climates
TownRatings has no climate map of the towns around Cornelius yet.
Climates most like Cornelius’, 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 |
|---|---|---|---|---|
| Cornelius, OR | 35° | 81° | 44" | 5.2" |
| Brigantine, NJ | 28° | 83° | 45" | 10" |
| Swannanoa, NC | 27° | 83° | 48" | 2.1" |
| Ben Lomond, CA | 40° | 79° | 43" | 0.0" |
| Ocean City, MD | 30° | 86° | 46" | 10" |
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 Cornelius averaged 1.3° warmer than the 1900s. The biggest change is in January (+3.1°).
A smaller shift than in 56% 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 Cornelius compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Cornelius’ place among Oregon’s.
Cornelius weather by month
Highs, lows and precipitation from NOAA’s grid at Cornelius’ center; snow, wet days and snow on the ground from Dilley 2 S, OR. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 47° | 35° | 6.9" | 1.6" | 20 | 2 | 35° – 46° |
| February | 51° | 35° | 5.0" | 1.6" | 15 | 1 | 37° – 49° |
| March | 56° | 37° | 4.8" | 0.0" | 18 | 0 | 43° – 52° |
| April | 61° | 40° | 3.2" | 0.0" | 16 | 0 | 46° – 56° |
| May | 68° | 46° | 2.1" | 0.0" | 12 | 0 | 52° – 62° |
| June | 73° | 50° | 1.3" | 0.0" | 8 | 0 | 58° – 68° |
| July | 81° | 54° | 0.4" | 0.0" | 3 | 0 | 61° – 71° |
| August | 82° | 54° | 0.5" | 0.0" | 3 | 0 | 64° – 71° |
| September | 76° | 50° | 1.4" | 0.0" | 6 | 0 | 59° – 65° |
| October | 64° | 43° | 3.6" | 0.0" | 12 | 0 | 49° – 58° |
| November | 53° | 38° | 6.7" | 0.3" | 19 | 0 | 40° – 50° |
| December | 46° | 34° | 8.1" | 1.7" | 21 | 1 | 36° – 44° |
| Year | 63° | 43° | 43.9" | 5.2" | 152 | 4 |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 37° to 49°. September is the most reliable, staying within 7°.
Where Cornelius’ 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 Cornelius’ center.
- Snow: Dilley 2 S, OR.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Forest Grove, OR, 2.5 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 Cornelius’ climate
What is the weather like in Cornelius?
A typical July afternoon reaches 81°, a January night drops to 35°, and about 5 inches of snow falls in a normal winter. Milder January nights than 81% of U.S. towns; cooler July afternoons than 87% of U.S. towns.
How cold does it get in Cornelius in winter?
December nights average 34°. About 61 nights a year reach 32° or below. In the coldest December of the last 30 years the month averaged 36°.
How much snow does Cornelius get?
About 5.2 inches in a normal winter at Dilley 2 S, OR, most of it in January, February and December, with snow on the ground about 4 days a year.
How hot does it get in Cornelius?
July, with a typical high of 81° and a low of 54°. About 23 days a year reach 90° and 2 reach 100° (Forest Grove, OR).
When is the first and last frost in Cornelius?
In half of years the last spring frost (32°) comes by April 16 and the first fall frost by October 26, about 192 frost-free days, at Forest Grove, OR.
What growing zone is Cornelius in?
Zone 8b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about 18°.
What is the best time of year to visit Cornelius?
By one simple rule (highs of 62–84° and lows of 40° or more), May, June, July, August, September and October. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Cornelius getting warmer?
Yes: 1991–2020 averaged 1.3° warmer than 1901–2000 on NOAA’s grid. A smaller shift than 56% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Cornelius.
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.