Reading KMA forecasts & weather indicators already covers what UV index, feels-like temperature, and fine-dust grades mean. Here we go one step further: what to actually do once a value crosses a given threshold. Based on public guidance from Korea's disease-control and environment authorities, here's a breakdown by threshold — exposure limits, illness-prevention steps, and mask and ventilation guidance.
The higher the UV index, the greater the risk of skin and eye damage from even brief exposure. Respond by band as follows.
| Index | Level | What to do |
|---|---|---|
| 0–2 | Low | No special precautions needed |
| 3–5 | Moderate | Seek shade around midday; SPF 30+ sunscreen recommended |
| 6–7 | High | Minimize direct sun 10 a.m.–2 p.m.; wear long sleeves, a hat, and sunglasses |
| 8–10 | Very high | Stay in shade, reapply sunscreen every 2 hours, avoid midday outdoor activity |
| 11+ | Extreme | Stay indoors when possible; if you must go out, fully cover exposed skin |
Feels-like temperature reflects the strain on your body more accurately than air temperature alone. Plan around it for both heat waves and cold snaps.
| Feels-like | Level | What to do |
|---|---|---|
| 33°C or above | Heat-advisory level | Avoid strenuous outdoor activity, drink water often, use shade or air-conditioned spaces |
| 35°C or above | Heat-warning level | Avoid outdoor work or exercise noon–5 p.m.; extra caution for older adults and children |
| 38°C or above | Very dangerous | Avoid non-essential outings; move to a cool place immediately at early symptoms (dizziness, muscle cramps) |
| Feels-like | Level | What to do |
|---|---|---|
| -12°C or below | Cold-advisory level | Minimize exposed skin with gloves and a scarf; wear proper cold-weather gear |
| -15°C or below | Cold-warning level | Avoid prolonged outdoor activity; watch fingers, toes, ears, and nose for frostbite |
On windy days, feels-like temperature can drop far below the actual reading — judge by feels-like, not air temperature alone.
The table below follows Korea's Ministry of Environment four-tier grading. For the exact concentration thresholds behind each grade, see comparing fine-dust grading standards.
| Grade | Outdoor activity | Mask | Ventilation |
|---|---|---|---|
| Good | No restrictions | Not needed | Freely |
| Moderate | Generally fine, even for sensitive groups | Not needed | Freely |
| Bad | Sensitive groups (children, older adults, respiratory conditions) shorten time outdoors | Sensitive groups: certified mask (KF80+) recommended | Brief and frequent, plus an air purifier |
| Very bad | Everyone should limit outdoor activity where possible | Certified mask (KF94) recommended when going out | Minimize except when unavoidable |
sanCheck shows live UV index, feels-like temperature, and fine-dust grade for your saved locations, and combines them into an outdoor-activity score that tells you at a glance whether it's a good time to head out. If one indicator matters most to you, try building your own rule around it.