
If you're renting a car in Korea between June and August, get ready for heat unlike anything most temperate-climate visitors have experienced. The official heatwave alert (폭염경보) kicks in when the heat index tops 35°C for two or more consecutive days — and that happens regularly in Seoul, Daegu, and most of the peninsula.
The heat is manageable with the right strategy. Korean expressways have excellent rest stops with full air conditioning, underground parking is abundant in cities, and rental cars come with powerful AC systems. But there are Korea-specific tricks worth knowing before you hit the road.

At a Glance
Peak Heat Season
July – mid-August
Average High (Seoul)
33°C / feels like 40°C
Hottest City
Daegu (nicknamed 'Korea's furnace')
Best Drive Times
Before 10 AM or after 7 PM
Emergency
119 (ambulance / heat illness)
Tourist Hotline
1330 (English, 24/7)
Korea's jangma (장마) monsoon runs from late June through late July, bringing heavy rain that briefly cools things down. But once jangma ends — usually around late July — temperatures spike sharply. August is the true danger zone. The heat island effect in Seoul and Daegu means city streets feel 3-5°C hotter than open countryside. Interior car temperatures can hit 78°C on a 35°C day if you park in direct sun.
The practical advice: plan your long driving days for the morning. Try to be at your destination or parked in shade by noon, then drive again after 5-6 PM when temperatures drop. Daegu, sitting in a basin surrounded by mountains, is the hottest city you'll pass through on the Gyeongbu Expressway — factor in a rest stop there rather than pushing through.
The biggest mistake tourists make is jumping straight into a hot parked car and blasting the AC. If your car has been parked in the sun, the interior air is 60-80°C — blasting recirculated hot air just cooks you faster. Instead, spend the first 60-90 seconds with all windows down and the AC set to 외기 (fresh air mode) to flush the oven air out, then switch to 내기 (recirculate) once the cabin starts to cool.

Underground parking (지하주차장, jija juchajang) is your best option in Korean cities. Most large department stores (Lotte, Hyundai, Shinsegae), supermarkets (E-Mart, Homeplus), and many attractions offer underground parking — often free for the first hour or two with a purchase. The temperature difference between surface and underground parking can be 15-20°C.

Heat causes the air inside your tires to expand. Tire pressure increases approximately 1-2 PSI for every 10°C rise in temperature — so if you set your pressure at a cool morning 32 PSI, by afternoon on the highway your tires could be at 36-38 PSI. Overinflated tires reduce the contact patch with the road, increasing braking distance on hot asphalt and raising blowout risk.

Korean expressway 휴게소 (hyu-ge-so) rest areas are phenomenal — large, clean, fully air-conditioned food courts with plenty of seating. In summer, they become genuine heatwave shelters. The rule of thumb is to stop every 90-120 minutes in normal conditions, but in peak summer heat, aim for every hour. Heat fatigue creeps up faster than you expect, especially when the AC is fighting hard and the sun is beating on the windshield.

Korea's summer heat is real, but foreign drivers manage it well every year with a little preparation. Plan your drives around the cooler hours, lean on Korea's excellent underground parking and rest stops, and keep your car properly cooled from the moment you get in. Drive safe — and enjoy the freedom of the open road, even in July.
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