When is the last frost in Rapid City, SD?

The average last spring frost (50% probability of 32°F) in Rapid City is around May 3, based on NOAA/NCEI 1991–2020 normals at the Rapid City Wfo, SD station (3.4 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 Rapid City?

The average first fall frost in Rapid City, SD is around October 8, giving roughly a 157-day frost-free growing season.

What planting zone is Rapid City, SD?

Rapid City 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 Rapid City?

In Rapid City, SD the warmest month is July (avg high 84.4°F) and the coldest is January (avg low 16.2°F). It averages about 20″ of precipitation a year and 53.7″ of snow.

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Rapid City, SD Planting Calendar & Frost Dates

USDA hardiness zone 5b · ZIP 57701 · elevation 1030′ · NOAA & USDA data

Rapid City is in USDA hardiness zone 5b (winters can dip to -15 to -10°F), with a growing season of about 157 days between the average last spring frost (May 3) and first fall frost (October 8). The warmest month is July (avg high 84.4°F); the coldest is January (avg low 16.2°F). It averages 20″ of precipitation a year and 53.7″ 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

May 3

avg (50% prob, 32°F)

First fall frost

October 8

avg (50% prob, 32°F)

Growing season

157 days

frost-free window

Warmest month

July

avg high 84.4°F

Month-by-month typical weather in Rapid City

Average conditions from the NOAA/NCEI 1991–2020 U.S. Climate Normals at Rapid City Wfo, SD (3.4 mi away). Temperatures °F, precipitation & snow in inches.

Month	Avg high	Avg low	Mean	Precip (in)	Snow (in)
January	36.5	16.2	26.4	0.3	5.3
February	38.3	17.5	27.9	0.5	9.1
March	47.4	25.6	36.5	0.9	10.4
April	55	34	44.5	2.3	10
May	65.3	44.6	54.9	4.1	2.2
June	76.2	54.6	65.4	3.3	0.1
July	84.4	61.6	73	2.6	0
August	83.4	59.9	71.6	2.2	0
September	74	50.8	62.4	1.4	0.1
October	58.8	37.9	48.3	1.5	3.4
November	47	26.6	36.8	0.5	6.5
December	37.6	18.6	28.1	0.4	6.6

What to plant when in Rapid City

Crop	Season	What to do & when
Tomatoes	warm	Start seeds indoors: March 22 · Transplant out: May 10
Peppers	warm	Start seeds indoors: March 8 · Transplant out: May 17
Cucumbers	warm	Direct sow: May 10
Zucchini / squash	warm	Direct sow: May 10
Bush beans	warm	Direct sow: May 10
Sweet corn	warm	Direct sow: May 10
Basil	warm	Transplant out: May 10
Peas	cool	Sow (spring): March 29 · Sow (fall): August 13
Spinach	cool	Sow (spring): March 22 · Sow (fall): August 13
Lettuce	cool	Sow (spring): April 5 · Sow (fall): August 13
Kale	cool	Transplant (spring): April 12 · Sow (fall): July 30
Broccoli	cool	Transplant (spring): April 19
Carrots	cool	Sow (spring): April 12 · Sow (fall): July 30
Onions	cool	Transplant (spring): April 5
Potatoes	cool	Plant seed potatoes: April 19
Radishes	cool	Sow (spring): April 5 · Sow (fall): August 27

Dates are computed from Rapid City'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 South Dakota

Sioux Falls, SD

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 — Rapid City Wfo, SD, 3.4 mi (confidence: high). Monthly weather normals: Rapid City Wfo, SD, 3.4 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.