When is the last frost in Gresham, OR?

The average last spring frost (50% probability of 32°F) in Gresham is around March 16, based on NOAA/NCEI 1991–2020 normals at the Portland Troutdale Ap, OR station (3.1 mi away). Half of years it falls outside that date, so wait 1–2 weeks past it before setting out frost-tender plants.

When is the first fall frost in Gresham?

The average first fall frost in Gresham, OR is around November 20, giving roughly a 250-day frost-free growing season.

What planting zone is Gresham, OR?

Gresham is in USDA plant hardiness zone 9a (average annual extreme minimum temperature 20 to 25°F), from the 2023 USDA Plant Hardiness Zone Map.

What is the weather like in Gresham?

In Gresham, OR the warmest month is August (avg high 81.9°F) and the coldest is December (avg low 36.1°F). It averages about 43.7″ of precipitation a year and 3.4″ of snow.

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Gresham, OR Planting Calendar & Frost Dates

USDA hardiness zone 9a · ZIP 97030 · elevation 6′ · NOAA & USDA data

Gresham is in USDA hardiness zone 9a (winters can dip to 20 to 25°F), with a growing season of about 250 days between the average last spring frost (March 16) and first fall frost (November 20). The warmest month is August (avg high 81.9°F); the coldest is December (avg low 36.1°F). It averages 43.7″ of precipitation a year and 3.4″ of snow, mostly mid-winter. Start cool-season crops several weeks before the last frost; wait until after it for tomatoes, peppers and other tender crops.

Hardiness zone

min temp 20 to 25°F

Last spring frost

March 16

avg (50% prob, 32°F)

First fall frost

November 20

avg (50% prob, 32°F)

Growing season

250 days

frost-free window

Warmest month

August

avg high 81.9°F

Month-by-month typical weather in Gresham

Average conditions from the NOAA/NCEI 1991–2020 U.S. Climate Normals at Portland Wfo, OR (6.2 mi away). Temperatures °F, precipitation & snow in inches.

Month	Avg high	Avg low	Mean	Precip (in)	Snow (in)
January	46.1	36.5	41.3	6	1
February	50.5	37.2	43.9	4.5	0.9
March	56.3	39.5	47.9	4.7	0.1
April	62	43.3	52.7	3.6	0
May	69.3	48.4	58.9	2.8	0
June	74	52.8	63.4	2	0
July	81.7	57	69.4	0.7	0
August	81.9	57.3	69.6	0.6	0
September	76	52.9	64.4	1.7	0
October	63.5	46.4	55	4	0
November	52.4	40.6	46.5	6.3	0
December	45.7	36.1	40.9	7	1.4

What to plant when in Gresham

Crop	Season	What to do & when
Tomatoes	warm	Start seeds indoors: February 2 · Transplant out: March 23
Peppers	warm	Start seeds indoors: January 19 · Transplant out: March 30
Cucumbers	warm	Direct sow: March 23
Zucchini / squash	warm	Direct sow: March 23
Bush beans	warm	Direct sow: March 23
Sweet corn	warm	Direct sow: March 23
Basil	warm	Transplant out: March 23
Peas	cool	Sow (spring): February 9 · Sow (fall): September 25
Spinach	cool	Sow (spring): February 2 · Sow (fall): September 25
Lettuce	cool	Sow (spring): February 16 · Sow (fall): September 25
Kale	cool	Transplant (spring): February 23 · Sow (fall): September 11
Broccoli	cool	Transplant (spring): March 2
Carrots	cool	Sow (spring): February 23 · Sow (fall): September 11
Onions	cool	Transplant (spring): February 16
Potatoes	cool	Plant seed potatoes: March 2
Radishes	cool	Sow (spring): February 16 · Sow (fall): October 9

Dates are computed from Gresham's average frost dates using standard cool-/warm-season timing. They're a starting point — a cold spring, a warm microclimate, or a fast-maturing variety can shift them by a week or two.

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Gear that helps you plant on time

Some links below are Amazon affiliate links (tag theboringthin-20). If you buy through them we may earn a small commission at no extra cost to you — it keeps this almanac free. We only list generic, genuinely-useful categories.

Soil thermometer →Know when the ground is warm enough to sow — the honest signal, not the calendar.Seed-starting trays + dome →Start tomatoes & peppers indoors on the schedule below.Seedling heat mat →Warms the soil for faster, more even germination indoors.Floating row cover / frost cloth →Buys you 4–8°F to beat an early or late frost.Raised garden bed kit →Warms and drains faster in spring than in-ground soil.Garden gloves →Basic kit for transplant day.

Nearby cities in Oregon

Portland, OR Lake Oswego, OR Beaverton, OR Hillsboro, OR Salem, OR Albany, OR Corvallis, OR Springfield, OR

Sources & method. Hardiness zone: 2023 USDA Plant Hardiness Zone Map (PRISM Climate Group, Oregon State University). Frost dates & growing season: NOAA/NCEI 1991–2020 U.S. Climate Normals, nearest station with published freeze normals — Portland Troutdale Ap, OR, 3.1 mi (confidence: high). Monthly weather normals: Portland Wfo, OR, 6.2 mi (confidence: high). ZIP centroid from U.S. Census 2023 ZCTA data. Frost dates are the 50%-probability date — half of years frost occurs outside the stated date. Nothing here is invented; where the nearest station is far, we say so. Last updated 2026-07-22.