When is the last frost in St. Peters, MO?

The average last spring frost (50% probability of 32°F) in St. Peters is around April 9, based on NOAA/NCEI 1991–2020 normals at the St Peters 2 Se, MO station (2.6 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 St. Peters?

The average first fall frost in St. Peters, MO is around October 26, giving roughly a 198-day frost-free growing season.

What planting zone is St. Peters, MO?

St. Peters is in USDA plant hardiness zone 6b (average annual extreme minimum temperature -5 to 0°F), from the 2023 USDA Plant Hardiness Zone Map.

What is the weather like in St. Peters?

In St. Peters, MO the warmest month is July (avg high 88.1°F) and the coldest is January (avg low 21.2°F). It averages about 42.3″ of precipitation a year and 14.8″ of snow.

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St. Peters, MO Planting Calendar & Frost Dates

USDA hardiness zone 6b · ZIP 63376 · elevation 175′ · NOAA & USDA data

St. Peters is in USDA hardiness zone 6b (winters can dip to -5 to 0°F), with a growing season of about 198 days between the average last spring frost (April 9) and first fall frost (October 26). The warmest month is July (avg high 88.1°F); the coldest is January (avg low 21.2°F). It averages 42.3″ of precipitation a year and 14.8″ 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 -5 to 0°F

Last spring frost

April 9

avg (50% prob, 32°F)

First fall frost

October 26

avg (50% prob, 32°F)

Growing season

198 days

frost-free window

Warmest month

July

avg high 88.1°F

Month-by-month typical weather in St. Peters

Average conditions from the NOAA/NCEI 1991–2020 U.S. Climate Normals at St Peters 2 Se, MO (2.6 mi away). Temperatures °F, precipitation & snow in inches.

Month	Avg high	Avg low	Mean	Precip (in)	Snow (in)
January	39.3	21.2	30.2	2.4	4.7
February	44.9	24.8	34.8	2.4	5
March	55.5	33.3	44.4	3.5	1.5
April	67.3	43.3	55.3	4.7	0.1
May	76.3	53.5	64.9	4.8	0
June	84.4	63.3	73.9	4.3	0
July	88.1	67.5	77.8	4.2	0
August	87.2	65.4	76.3	3.8	0
September	80.8	57.1	68.9	3.1	0
October	68.5	45.2	56.9	3.1	0
November	54.9	35	44.9	3.5	0.8
December	43.6	26.5	35	2.6	2.7

What to plant when in St. Peters

Crop	Season	What to do & when
Tomatoes	warm	Start seeds indoors: February 26 · Transplant out: April 16
Peppers	warm	Start seeds indoors: February 12 · Transplant out: April 23
Cucumbers	warm	Direct sow: April 16
Zucchini / squash	warm	Direct sow: April 16
Bush beans	warm	Direct sow: April 16
Sweet corn	warm	Direct sow: April 16
Basil	warm	Transplant out: April 16
Peas	cool	Sow (spring): March 5 · Sow (fall): August 31
Spinach	cool	Sow (spring): February 26 · Sow (fall): August 31
Lettuce	cool	Sow (spring): March 12 · Sow (fall): August 31
Kale	cool	Transplant (spring): March 19 · Sow (fall): August 17
Broccoli	cool	Transplant (spring): March 26
Carrots	cool	Sow (spring): March 19 · Sow (fall): August 17
Onions	cool	Transplant (spring): March 12
Potatoes	cool	Plant seed potatoes: March 26
Radishes	cool	Sow (spring): March 12 · Sow (fall): September 14

Dates are computed from St. Peters'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 Missouri

St. Charles, MO Chesterfield, MO Florissant, MO St. Louis, MO Jefferson City, MO Columbia, MO Cape Girardeau, MO Springfield, MO

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 — St Peters 2 Se, MO, 2.6 mi (confidence: high). Monthly weather normals: St Peters 2 Se, MO, 2.6 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.