When is the last frost in Oshkosh, WI?

The average last spring frost (50% probability of 32°F) in Oshkosh is around April 24, based on NOAA/NCEI 1991–2020 normals at the Oshkosh, WI 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 Oshkosh?

The average first fall frost in Oshkosh, WI is around October 20, giving roughly a 178-day frost-free growing season.

What planting zone is Oshkosh, WI?

Oshkosh is in USDA plant hardiness zone 5b (average annual extreme minimum temperature -15 to -10°F), from the 2023 USDA Plant Hardiness Zone Map.

What is the weather like in Oshkosh?

In Oshkosh, WI the warmest month is July (avg high 81.7°F) and the coldest is January (avg low 10.2°F). It averages about 33.3″ of precipitation a year and 39.2″ of snow.

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Oshkosh, WI Planting Calendar & Frost Dates

USDA hardiness zone 5b · ZIP 54901 · elevation 229′ · NOAA & USDA data

Oshkosh is in USDA hardiness zone 5b (winters can dip to -15 to -10°F), with a growing season of about 178 days between the average last spring frost (April 24) and first fall frost (October 20). The warmest month is July (avg high 81.7°F); the coldest is January (avg low 10.2°F). It averages 33.3″ of precipitation a year and 39.2″ 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 -15 to -10°F

Last spring frost

April 24

avg (50% prob, 32°F)

First fall frost

October 20

avg (50% prob, 32°F)

Growing season

178 days

frost-free window

Warmest month

July

avg high 81.7°F

Month-by-month typical weather in Oshkosh

Average conditions from the NOAA/NCEI 1991–2020 U.S. Climate Normals at Oshkosh, WI (3.1 mi away). Temperatures °F, precipitation & snow in inches.

Month	Avg high	Avg low	Mean	Precip (in)	Snow (in)
January	26.1	10.2	18.1	1.3	9.8
February	29.9	12.9	21.4	1.1	10.1
March	41.3	23.5	32.4	1.9	5.4
April	54.4	35.7	45	3.2	1.8
May	67.3	48	57.7	3.9	0
June	77.3	58.8	68	4.8	0
July	81.7	62.7	72.2	3.8	0
August	79.8	61	70.4	3.4	0
September	72.5	52.7	62.6	3.3	0
October	59	40.8	49.9	2.9	0.3
November	44.2	28.9	36.6	2.1	1.8
December	31.8	17.5	24.7	1.6	10

What to plant when in Oshkosh

Crop	Season	What to do & when
Tomatoes	warm	Start seeds indoors: March 13 · Transplant out: May 1
Peppers	warm	Start seeds indoors: February 27 · Transplant out: May 8
Cucumbers	warm	Direct sow: May 1
Zucchini / squash	warm	Direct sow: May 1
Bush beans	warm	Direct sow: May 1
Sweet corn	warm	Direct sow: May 1
Basil	warm	Transplant out: May 1
Peas	cool	Sow (spring): March 20 · Sow (fall): August 25
Spinach	cool	Sow (spring): March 13 · Sow (fall): August 25
Lettuce	cool	Sow (spring): March 27 · Sow (fall): August 25
Kale	cool	Transplant (spring): April 3 · Sow (fall): August 11
Broccoli	cool	Transplant (spring): April 10
Carrots	cool	Sow (spring): April 3 · Sow (fall): August 11
Onions	cool	Transplant (spring): March 27
Potatoes	cool	Plant seed potatoes: April 10
Radishes	cool	Sow (spring): March 27 · Sow (fall): September 8

Dates are computed from Oshkosh'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 Wisconsin

Appleton, WI Fond Du Lac, WI Green Bay, WI Sheboygan, WI Brookfield, WI Waukesha, WI Milwaukee, WI New Berlin, WI

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 — Oshkosh, WI, 3.1 mi (confidence: high). Monthly weather normals: Oshkosh, WI, 3.1 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.