South Korea: frost dates by city

The average last spring frost and first autumn frost in 10 cities of South Korea, from ten years of weather. The last spring frost comes earliest in Jeju City and latest in Chuncheon.

City	Last spring frost	First autumn frost	Frost-free days	Soil at 10 °C	Tomato: planting out	Places to buy (OpenStreetMap)
Jeju City	18 February	19 December	304 days	7 March	11 April – 29 August	9
Busan	19 March	22 November	248 days	23 March	21 April – 2 August	27
Daegu	19 March	21 November	247 days	27 March	22 April – 1 August	33
Gangneung	19 March	21 November	247 days	30 March	28 April – 1 August	—
Ulsan	22 March	16 November	239 days	24 March	22 April – 27 July	10
Jeonju	27 March	17 November	235 days	29 March	25 April – 28 July	7
Seoul	29 March	6 November	222 days	1 April	24 April – 17 July	88
Daejeon	1 April	12 November	225 days	29 March	24 April – 23 July	25
Gwangju	1 April	23 November	236 days	28 March	24 April – 3 August	16
Chuncheon	6 April	31 October	208 days	9 April	13 May – 11 July	2

The last spring frost comes 47 days later in Chuncheon (6 April) than in Jeju City (18 February). The frost-free season lasts 208–304 days. The top 7 cm of soil reaches 10 °C first in Jeju City (7 March) and last in Chuncheon (9 April).

Gardening in South Korea: climate zones and crops by region

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.