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Last and first frost dates in St. George

United States

In St. George the last spring frost usually comes around 7 March and the first autumn frost around 20 November, which leaves about 258 frost-free days (median of 2016–2025). Tomato seedlings can go into open ground from 27 March to 31 July.

Last spring frostaround 7 March
First autumn frostaround 20 November
Frost-free days258 days

Median of 2016–2025 for the 25 km grid cell of the city: the last day at or below 0 °C in spring and the first in autumn (ERA5 reanalysis via Open-Meteo). In a cold year a frost can come a week or two later — Greenly warns 48 hours ahead.

When is the last frost in St. George?

The last frost in St. George usually comes around 7 March: that is the median of 2016–2025, so in about half of those years the last night at or below 0 °C came later. Hardy crops start before it and frost-tender ones only after it: in the table below arugula can go into open ground from 14 February, while corn waits until 14 March. The first autumn frost follows around 20 November, about 258 days later: harvest or cover frost-tender crops before then.

When to sow and plant

CropSow for seedlingsPlant out in a greenhouseOpen ground
Achocha12 January – 12 August21 February – 21 September14 March – 21 September
Ageratumfrom 9 January—from 27 March
Arugula——sow 14 February – 16 October
Basil6 February – 18 September16 March – 26 October6 April – 26 October
Beet——sow 14 February – 21 September
Bell Pepper15 January – 1 June16 March – 31 July6 April – 31 July
Black-eyed Susanfrom 21 December—from 14 March
Bok Choy17 January – 29 September21 February – 3 November14 March – 3 November
Borage——sow 14 March – 26 September
Broad bean——sow 14 February – 12 August
Broccoli——sow 14 February – 5 August
Brussels Sprouts10 December – 3 July24 January – 17 August14 February – 17 August
Busy Lizziefrom 20 December—from 14 March
Cabbage——sow 14 February – 13 July
Calendula——sow from 14 February
Carrot——sow 14 February – 28 August
Cauliflower13 December – 5 August24 January – 16 September14 February – 16 September
Celeriac6 December – 2 June21 February – 18 August14 March – 18 August
Celery6 December – 12 June21 February – 28 August14 March – 28 August
Celosiafrom 25 Januaryfrom 11 Marchfrom 1 April
Chamomile——sow 14 February – 16 September
Chayote25 November – 26 May21 February – 22 August14 March – 22 August
Chickpea——sow 14 February – 2 August
Chicory30 December – 27 August—14 February – 21 September
Chili Pepper15 January – 8 July16 March – 6 September6 April – 6 September
China asterfrom 23 Januaryfrom 16 Marchfrom 6 April
Chives——sow 14 February – 7 September
Cilantro——sow 14 February – 17 September
Corn——sow 14 March – 2 August
Corn poppy——sow from 14 February
Cosmosfrom 25 Januaryfrom 11 Marchfrom 1 April
Cucumber16 February – 8 August16 March – 5 September6 April – 5 September
Daikon——sow 14 February – 14 September
Delphiniumfrom 26 November—from 14 February
Dill——sow 14 February – 27 September
Edging lobeliafrom 20 December—from 14 March
Eggplant15 January – 1 June16 March – 31 July6 April – 31 July
Florence fennel7 January – 12 August21 February – 26 September14 March – 26 September
Foxglovefrom 8 November—from 14 February
Garden sorrel——sow 14 February – 15 September
Green Beans——sow 1 April – 10 August
Hollyhock——sow from 14 February
Hyssop——sow 14 February – 8 August
Kale——sow 14 February – 9 September
Kiwano2 February – 15 August6 March – 16 September27 March – 16 September
Kohlrabi——sow 14 February – 19 September
Leek15 November – 24 May24 January – 2 August14 February – 2 August
Lemon balm——sow 14 February – 11 September
Lettuce——sow 14 February – 24 September
Lisianthusfrom 29 Octoberfrom 24 Januaryfrom 14 February
Lovage——sow from 14 February
Luffa2 February – 9 June16 March – 21 July6 April – 21 July
Marigoldfrom 10 Januaryfrom 21 Februaryfrom 14 March
Marjoram15 January – 27 August—6 April – 26 October
Melon16 February – 26 July16 March – 23 August6 April – 23 August
Microgreens——sow 1 April – 6 November
Moringa29 January – 1 September25 March – 26 October15 April – 26 October
Moss rosefrom 27 December—from 14 March
Mustard greens——sow 14 February – 6 October
Napa cabbage19 January – 6 September21 February – 9 October14 March – 9 October
Nasturtiumfrom 14 Januaryfrom 21 Februaryfrom 14 March
Okra2 February – 20 August16 March – 1 October6 April – 1 October
Oregano25 November – 17 August24 January – 16 October14 February – 16 October
Pansyfrom 29 Novemberfrom 24 Januaryfrom 14 February
Parsley——sow 14 February – 5 September
Parsnip——sow 14 February – 25 July
Peanut7 February – 16 July16 March – 22 August6 April – 22 August
Peas——sow 14 February – 7 September
Petuniafrom 12 Januaryfrom 16 Marchfrom 6 April
Physalis20 January – 13 July6 March – 27 August27 March – 27 August
Pumpkin2 February – 14 June16 March – 26 July6 April – 26 July
Purple coneflowerfrom 23 November—from 14 February
Radish——sow 14 February – 21 October
Sage6 December – 13 August24 January – 1 October14 February – 1 October
Scarlet sagefrom 13 January—from 27 March
Snapdragonfrom 20 Novemberfrom 24 Januaryfrom 14 February
Soybean——sow 6 April – 1 September
Spinach——sow 14 February – 26 September
Stevia16 January – 4 July6 March – 22 August27 March – 22 August
Stock——sow from 14 February
Sunflower——sow from 1 April
Sweet alyssum——sow from 14 February
Sweet Corn2 February – 27 August24 February – 18 September17 March – 18 September
Sweet peafrom 13 Decemberfrom 24 Januaryfrom 14 February
Sweet William——sow from 14 February
Swiss Chard——sow 14 February – 21 September
Thyme——sow 14 February – 2 August
Tomato13 January – 9 June6 March – 31 July27 March – 31 July
Turnip——sow 14 February – 23 September
Watercress——sow 14 February – 4 October
Watermelon16 February – 14 July16 March – 11 August6 April – 11 August
Zinniafrom 18 Februaryfrom 25 Marchfrom 15 April
Zucchini23 February – 13 August16 March – 3 September6 April – 3 September

Planting out: a week after the last frost once the soil is warm enough for the crop; frost-hardy crops three weeks before it; an unheated greenhouse three weeks earlier. Seedlings are sown so they are ready on that day. Each window starts on the Greenly calendar date and ends on the last day that still leaves the crop’s days to harvest (from its card) before the average first autumn frost, plus six weeks of picking for crops harvested over weeks (tomatoes, peppers, aubergines, cucumbers, courgettes, pumpkins, watermelons, beans) — our rule; earlier in the window is safer.

When the soil warms up in St. George

The day the top 7 cm of soil first averages each temperature over a week, median of 2016–2025 (ERA5 via Open-Meteo). The soil reaches 10 °C 12 days before the last spring frost and 15 °C 20 days after it.

SoilDateAgainst the last spring frost
5 °C19 January47 days earlier
10 °C23 February12 days earlier
15 °C27 March20 days later
18 °C6 April30 days later

Frost dates near St. George

Of the nearest cities on our list, the last spring frost ends earliest in Phoenix (4 February) and latest in Flagstaff (5 May).

CityDistanceLast spring frostFirst autumn frost
Las Vegas173 km6 February12 December
Flagstaff277 km5 May21 October
Provo386 km6 April7 November
Phoenix428 km4 February29 December
Salt Lake City432 km24 April26 October

What to grow at home in winter in St. George

Frosts in St. George usually come from about 20 November to about 7 March. These plants have indoor care in their Greenly cards and are harvested quickly, so they can be sown on a windowsill in winter.

Weather in St. George by month

Average weather in St. George over 2016–2025: the warmest month is July. Months that average 20 °C or more by day: April–October (24.9–38.9 °C). Months that average 30 °C or more by day: June–September (33.3–38.9 °C). Nights average below 0 °C in January (-0.2 °C). About 206 mm of rain falls in a year, on 36 days; March is the wettest month (33 mm) and June the driest (2 mm).

MonthDay, °CNight, °CRain, mmRainy days
January10.5-0.2305
February14.21.4325
March18.55.1336
April24.99.7122
May29.514.662
June36.62120
July38.924.472
August37.322.8113
September33.318.3102
October25.610.4112
November17.24.2243
December11.70.5284

Average of the daily highs and lows, rain per month and days with at least 1 mm (ERA5 via Open-Meteo, the same grid cell as the frost dates).

Planted in autumn

CropWhen to plant
Bearded Irisby 21 October
Crocusby 21 October
Daffodilby 21 October
Garlic21 October – end of December
Grape hyacinthby 21 October
Helleboreby 21 October
Hyacinthby 21 October
Lilyby 21 October
Ornamental onionby 21 October
Peonyby 21 October
Saffronby 21 October
Snowdropby 21 October
Tulipby 21 October
Wild garlicby 21 October

From a month before the first autumn frost, so the roots grow before winter, to the late-planting limit on each crop’s page (about two weeks before the ground freezes, by ten years of weather).