When is the last frost in Twin Falls, ID?

The average last spring frost (50% probability of 32°F) in Twin Falls is around May 9, based on NOAA/NCEI 1991–2020 normals at the Twin Falls Sun Vly Rgnl Ap, ID station (5.9 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 Twin Falls?

The average first fall frost in Twin Falls, ID is around October 4, giving roughly a 147-day frost-free growing season.

What planting zone is Twin Falls, ID?

Twin Falls 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 Twin Falls?

In Twin Falls, ID the warmest month is July (avg high 88.4°F) and the coldest is December (avg low 20.1°F). It averages about 10.3″ of precipitation a year.

Home › Idaho › Twin Falls

Twin Falls, ID Planting Calendar & Frost Dates

USDA hardiness zone 6b · ZIP 83301 · elevation 1265′ · NOAA & USDA data

Twin Falls is in USDA hardiness zone 6b (winters can dip to -5 to 0°F), with a growing season of about 147 days between the average last spring frost (May 9) and first fall frost (October 4). The warmest month is July (avg high 88.4°F); the coldest is December (avg low 20.1°F). It averages 10.3″ of precipitation a year. 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

May 9

avg (50% prob, 32°F)

First fall frost

October 4

avg (50% prob, 32°F)

Growing season

147 days

frost-free window

Warmest month

July

avg high 88.4°F

Month-by-month typical weather in Twin Falls

Average conditions from the NOAA/NCEI 1991–2020 U.S. Climate Normals at Twin Falls Sun Vly Rgnl Ap, ID (5.9 mi away). Temperatures °F, precipitation & snow in inches.

Month	Avg high	Avg low	Mean	Precip (in)	Snow (in)
January	37	21.1	29.1	1	–
February	41.8	23.8	32.8	0.7	–
March	52.2	29.7	40.9	1	–
April	58.7	34.3	46.5	1.1	–
May	68.7	42.2	55.4	1.5	–
June	78.2	49.4	63.8	1	–
July	88.4	57.7	73	0.3	–
August	86.8	55.8	71.3	0.4	–
September	76.4	47.1	61.8	0.5	–
October	62.3	36.4	49.3	0.8	–
November	47.2	26	36.6	0.8	–
December	36.9	20.1	28.5	1.2	–

What to plant when in Twin Falls

Crop	Season	What to do & when
Tomatoes	warm	Start seeds indoors: March 28 · Transplant out: May 16
Peppers	warm	Start seeds indoors: March 14 · Transplant out: May 23
Cucumbers	warm	Direct sow: May 16
Zucchini / squash	warm	Direct sow: May 16
Bush beans	warm	Direct sow: May 16
Sweet corn	warm	Direct sow: May 16
Basil	warm	Transplant out: May 16
Peas	cool	Sow (spring): April 4 · Sow (fall): August 9
Spinach	cool	Sow (spring): March 28 · Sow (fall): August 9
Lettuce	cool	Sow (spring): April 11 · Sow (fall): August 9
Kale	cool	Transplant (spring): April 18 · Sow (fall): July 26
Broccoli	cool	Transplant (spring): April 25
Carrots	cool	Sow (spring): April 18 · Sow (fall): July 26
Onions	cool	Transplant (spring): April 11
Potatoes	cool	Plant seed potatoes: April 25
Radishes	cool	Sow (spring): April 11 · Sow (fall): August 23

Dates are computed from Twin Falls'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.

Want the exact dates for your yard? →
Look up your precise ZIP-code frost dates and a full 26-crop planting calendar on our free interactive tool.
Open the frost & planting tool

🌾 Get a frost reminder

One email in early spring and early fall with the dates for your area. No spam.

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 Idaho

Pocatello, ID Meridian, ID Nampa, ID Caldwell, ID Idaho Falls, ID

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 — Twin Falls Sun Vly Rgnl Ap, ID, 5.9 mi (confidence: high). Monthly weather normals: Twin Falls Sun Vly Rgnl Ap, ID, 5.9 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.