South Korea has two good windows: Apr–Jun and Sep–Oct. They sit either side of the season the climate record rules out, which is why the shoulder months matter here. The recommended window is May–Jun, Sep–Oct.
Rainy Jun–Jul, typhoons Aug–Sep
| Month | High °C | High °F | Rainy days | Verdict |
|---|---|---|---|---|
| January | 0.6 | 33 | 14% | Too cold |
| February | 3.3 | 38 | 15% | Too cold |
| March | 8.8 | 48 | 20% | Fair |
| April | 15.3 | 60 | 24% | Go |
| May | 20.9 | 70 | 26% | Go |
| June | 25.2 | 77 | 34% | Go |
| July | 27.4 | 81 | 58% | Too wet |
| August | 28.1 | 83 | 56% | Fair |
| September | 24.2 | 76 | 34% | Go |
| October | 18.3 | 65 | 20% | Go |
| November | 10.6 | 51 | 26% | Fair |
| December | 3.0 | 37 | 16% | Too cold |
Verdict combines mean daytime high with rainy-day frequency. “Rainy days” is the share of days in the month with at least 1 mm of rain.
January is the driest month, with rain on 14% of days and daytime highs near 0.6°C (33°F). July is the wettest, at 58%. Temperature swings hard across the year — 27.5°C between August (28.1°C / 83°F) and January (0.6°C / 33°F) — so packing for the wrong month is the main risk. The record rules out too cold in Dec–Feb; too wet in July.