Frost dates for Portland, Oregon
In Portland, half of springs have had their last frost by March 13 (and 1 spring in 10 still has one after April 1), and half of falls have had their first frost by November 19, leaving about 247 frost-free days in a typical year. Here is how sure those dates are, what they mean for planting, and where they come from.
Frost dates for
Portland, Oregon
Last spring frost
March 13
Half of springs have their last frost by this date. For a safer bet, wait until April 1: only 1 spring in 10 has a frost after that.
First fall frost
November 19
Half of falls have their first frost by this date. In 1 fall in 10 it comes by October 29.
Growing season
247 days
Frost-free days in a typical year. 9 years in 10 get at least 219.
Hardiness zone
8b
2023 USDA map: the coldest night of winter averages 15°F to 20°F. It was 8b on the 2012 map too. ZIP codes within about 6 miles of the city's center: 8 in 8b and 15 in 9a.
Stations near you disagree. NOAA's Portland International Airport (4 miles away, at 20 feet above sea level), the one we used, gives a typical last frost of March 13 and a typical first frost of November 19. NOAA's Portland KGW-TV (2 miles away, at 160 feet above sea level) gives a typical last frost of February 25 and a typical first frost of December 1. So the typical last frost could fall anywhere from February 25 to March 13 and the typical first frost from November 19 to December 1, depending on whether your garden is more like one or the other. Local terrain matters: hillsides, valley floors, water and city heat can change frost dates a lot over a few miles. Treat the dates here as a starting point, and compare with a nearby gardener or your county extension office.
Print a year planner for Portland
Frost risk through the year
How sure are these dates?
A frost date is a probability, not a promise. NOAA worked out, from 30 years of nightly lows, how often the last spring frost and the first fall frost fall on each date. The middle column is the typical year. The outer columns are the early and late years that come about once a decade.
| Early year 1 in 10 | Typical year 1 in 2 | Late year 1 in 10 | |
|---|---|---|---|
| Last frost in spring | February 22 | March 13 | April 1 |
| First frost in fall | October 29 | November 19 | December 10 |
The frost-free season between them runs 247 days in a typical year. In 1 year in 10 it is 277 days or longer, and in 1 year in 10 it is 219 days or shorter.
- Hard freeze (28°F): about 98 years in 100 have one. In those years the last typically comes on February 16 and the first on December 5. It is a harder freeze than the 32°F frost line, cold enough to damage many garden plants; how hardy a crop is decides whether it comes through. (The National Weather Service's own hard-freeze threshold varies from office to office.)
- Frost possible (36°F at the station): typically last on April 6 and first on November 2. On clear, still nights the ground can be several degrees colder than the thermometer, so frost can form on plants when the official reading is in the mid-30s.
In 8 springs out of 10, the last frost in Portland comes between February 22 and April 1, a window of 38 days. That is wider than at most NOAA stations (the typical window is 31 days), so spring here is less predictable than average: lean toward the later date.
Among Oregon's 162 NOAA stations with a frost every year, 96 percent have their typical last frost later than Portland does.
Planting calendar for Portland
These dates count from the typical last and first frosts, using the planting rules published by Colorado State University Extension (spring), Virginia Cooperative Extension (fall crops) and University of Minnesota Extension (garlic, where winters are hard). Weather in any one year can run early or late, so check the forecast before you plant tender crops.
We don't give a garlic date here. The rule we use, from the University of Minnesota Extension, counts from the first killing frost, and it works where a hard freeze comes every year before the ground freezes. Your county's extension office can tell you when to plant garlic in your climate.
| When | What to do | Why then |
|---|---|---|
| January | ||
| January 9 to February 6 | Cauliflower Start seeds indoors | 5 to 7 weeks before planting out |
| January 23 to February 13 | Eggplant Start seeds indoors | 6 to 9 weeks before planting out |
| January 30 to February 13 | Peppers Start seeds indoors | 6 to 8 weeks before planting out |
| February | ||
| February 6 to 20 | Tomatoes Start seeds indoors | 5 to 7 weeks before planting out |
| February 13 to 27 | Peas, spinach, lettuce, radishes, onion sets, turnips Sow outdoors, as early as | hardy crops: 2 to 4 weeks before the typical last frost |
| February 13 to 27 | Broccoli and cabbage Plant out, as early as | hardy crops: 2 to 4 weeks before the typical last frost |
| February 27 to March 13 | Beets, carrots, potatoes, Swiss chard Plant outdoors, as early as | semi-hardy crops: up to 2 weeks before the typical last frost |
| February 27 to March 13 | Cauliflower Plant out, as early as | semi-hardy: up to 2 weeks before the typical last frost |
| March | ||
| March 13 | Snap beans, sweet corn, cucumbers, summer squash Sow outdoors around | tender crops: around the typical last frost date |
| March 27 | Tomatoes, peppers, eggplant Plant out from | very tender: 2 weeks or more after the typical last frost |
| March 27 | Melons, winter squash, pumpkins, lima beans Sow outdoors from | very tender: 2 weeks or more after the typical last frost |
| June | ||
| June 24 to July 8 | Cabbage for fall Start seeds | set the plants out by August 12 |
| July | ||
| July 14 to 28 | Broccoli for fall Start seeds | set the plants out by September 1 |
| August | ||
| August 23 | Snap beans for fall Last date to sow | 60 days to harvest, plus 2 weeks for slower fall growth, plus 2 weeks because frost kills it |
| August 27 | Carrots for fall Last date to sow | 70 days to harvest, plus 2 weeks for slower fall growth |
| August 28 | Cucumbers for fall Last date to sow | 55 days to harvest, plus 2 weeks for slower fall growth, plus 2 weeks because frost kills it |
| September | ||
| September 1 | Peas for fall Last date to sow | 65 days to harvest, plus 2 weeks for slower fall growth |
| September 2 | Summer squash for fall Last date to sow | 50 days to harvest, plus 2 weeks for slower fall growth, plus 2 weeks because frost kills it |
| September 6 | Leaf lettuce and beets for fall Last date to sow | 60 days to harvest, plus 2 weeks for slower fall growth |
| September 16 | Turnips and kohlrabi for fall Last date to sow | 50 days to harvest, plus 2 weeks for slower fall growth |
| September 26 | Spinach for fall Last date to sow | 40 days to harvest, plus 2 weeks for slower fall growth |
| October | ||
| October 6 | Radishes for fall Last date to sow | 30 days to harvest, plus 2 weeks for slower fall growth |
| October 29 | Tomatoes, peppers, squash, melons, cucumbers Watch the forecast from | in 1 fall in 10 the first frost comes by this date; pick tender crops before a frost |
| December | ||
| December 26 to January 23 | Broccoli and cabbage Start seeds indoors | 5 to 7 weeks before planting them out |
Want more insurance? Shift every spring date 19 days later. That plans around April 1, the date after which only 1 spring in 10 has a frost.
For spring bulbs such as tulips and daffodils, plant once the soil has cooled to about 50 to 55°F and keep going until a couple of weeks before the ground freezes. Our guide to fall planting explains how to tell.
Where these numbers come from
These dates come from NOAA's weather station Portland International Airport (station USW00024229), 4 miles from the center of Portland. It sits 150 feet lower, at 20 feet above sea level. NOAA rates this station's record as standard: at least 24 of the 30 years, with gaps filled from nearby stations.
The same station also gives the frost dates for Milwaukie.
Our ZIP code lookup matches these 4 ZIP codes to the same station, so they get the same dates: 97208, 97209, 97211, 97218. Hardiness zones are worked out separately for each ZIP code.
Nearby places
- Vancouver, Washington: last frost around March 29, first frost around November 9 (7 miles away)
- Gresham, Oregon: last frost around March 16, first frost around November 20 (10 miles away)
- Hillsboro, Oregon: last frost around April 16, first frost around October 23 (15 miles away)
See frost dates across Oregon, or look up your own ZIP code for the station nearest you. Want the background? Read what a last frost date really means.