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Voykit

Heat & UV planner

Pick a city and get the next 7 days: how hot it feels, the heat-risk band, the UV index, the cool hours to walk, how much water to carry and when to put sunscreen back on.

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City and day out

The forecast comes from Open-Meteo when you tap; nothing is sent about you except the city's coordinates.

Heat-risk bands

Heat index (temperature plus humidity, in the shade) categories from the US National Weather Service. Full sun can add up to about 8°C (15°F).

BandHeat indexWhat can happen
Caution27–32°C (80–90°F)Fatigue is possible with long exposure and activity.
Extreme caution32–39°C (90–103°F)Heat cramps and heat exhaustion possible with long exposure and activity.
Danger39–52°C (103–125°F)Heat cramps and heat exhaustion likely; heat stroke possible with long exposure and activity.
Extreme danger52°C (125°F)+Heat stroke highly likely.

UV index categories (WHO): 0–2 low, 3–5 moderate, 6–7 high, 8–10 very high, 11+ extreme. Protect your skin from 3 up.

Staying cool

  • Plan indoor sights (museums, malls, covered markets) for the hot middle of the day, and walk early and late.
  • Drink before you're thirsty and add salt or an electrolyte sachet when you sweat a lot; don't drink more than about 1.5 L an hour.
  • Light, loose, light-coloured clothes, a wide-brimmed hat and sunglasses; seek shade between 11:00 and 15:00.
  • Heat exhaustion: heavy sweating, dizziness, headache, nausea, cramps — get to shade or AC, cool the skin, sip water.
  • Heat stroke is an emergency: hot skin, confusion, fainting or no sweating — call emergency services and cool the person at once.
  • Children, older travellers, pregnancy and some medicines (diuretics, some blood-pressure and mental-health drugs) raise the risk.

General information, not medical advice. Water amounts are a rough guide for a healthy adult walking (checked 2026-09); needs vary with body size, pace and sweat. Keep the local emergency number handy, and your health card if you take regular medicines.