Seoul in May 2025: What the Weather Was Actually Like
Everyone told me May in Seoul was “mild.” Then it swung from 8°C (46°F) to 31°C (87°F) in the same month. Here’s what the data actually says — and what to wear.
May is one of the most-hyped months to visit Korea, and honestly, it deserves it. But it’s sneakier than people think. One day you’re in a t-shirt drinking iced Americano at an outdoor café. Two days later you’re digging for that jacket you almost left behind. That 22°C (72°F) average hides a lot.
Here’s 2025 Seoul May weather broken down with real data — so you can actually pack right.
For context, the 10-year average (2016–2025) for Seoul in May sits at 18.7°C (65°F) with highs around 24.2°C (75°F). So 2025 ran slightly cooler than usual — which actually made it more comfortable for sightseeing.
This is the thing nobody tells you. Early May and late May feel completely different. Plan your outfits accordingly.
| Period | Avg high | Avg low | Vibe |
|---|---|---|---|
| Early May (1–15) | 20–23°C (68–73°F) | 11–14°C (52–57°F) | Classic spring — breezy, crisp mornings |
| Late May (16–31) | 25–31°C (77–87°F) | 15–18°C (59–64°F) | Pre-summer mode — hot afternoons, AC indoors |
Koreans call this weather shift 환절기 (hwanjeorlgi) — the transitional season. There’s a whole clothing style built around it: t-shirt underneath, overshirt or light jacket on top, ready to peel off as the afternoon heats up. Steal the strategy.
What do Koreans actually wear? In Hongdae and Seongsu you’ll see oversized tees under open button-ups, wide-leg pants, clean sneakers. That transitional layered look. Nobody’s in a heavy coat, but nobody’s in full summer mode either.
Office workers keep a thin cardigan at their desk because Korean AC is aggressive year-round. Even in May. Pack one, even if you think you won’t need it.
Short answer: yes, keep a compact one in your bag. May isn’t rainy season — that’s July — but occasional afternoon showers do happen. In 2025, there were a few scattered rain days mostly mid-month. Nothing like monsoon, but enough to catch you off guard in Gyeongbokgung.
Sunscreen is non-negotiable. SPF 50 minimum. The May UV index in Korea regularly hits 6–7. Koreans take sun protection seriously in May — follow their lead.
May 8th is 어버이날 (Parents’ Day) — carnation sellers pop up on every street corner. Buddha’s Birthday brings lotus lanterns to temples like Jogyesa. Outdoor markets and pop-up events are everywhere from Seongsu to Mangwon.
The light in May is different. Clear and golden, before the summer haze settles in. If you picked May to visit Seoul, you made the right call. Just don’t forget that jacket.
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