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Weather: OpenWeatherMap · updated every 10 min
UV Index
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Heat Stress Adult
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Child Heat Safety.
3-day WBGT forecast — is it safe for your child to be outside?
Free · science-based · any city worldwide
Checking heat conditions...
⚠ Why children are at higher risk
Children's bodies overheat faster and cool down slower than adults.
They absorb more heat relative to body mass, sweat less efficiently,
and cannot always recognise or communicate distress.
Heat stress in children can escalate to heat stroke within minutes —
and under age 5, the risk is highest.
3–5×
faster overheating vs adults
WBGT
medical standard, WHO & military
<5
years — highest risk group
🔬 WBGT: Liljegren / Dimiceli (2013) + Stull (2011) ·
Solar radiation: NASA POWER XGBoost ML model (R²=0.96) ·
Forecast: OpenWeatherMap 5-day ·
Thresholds: WHO / ACSM children's heat guidelines
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Keeps Vitamin D & Activity data from sunrise, every day
Safe sun time for Vitamin D
Sunlight is your body's most natural source of vitamin D — for most healthy people, regular safe sun exposure (like the UV 3–5 window below) covers most or all of what the body needs, without relying on supplements. Sun exposure does have real limits though: winter at high latitudes, always-covered skin, sunscreen, older age, or spending most days indoors can all cut how much you make — that's when a supplement becomes the practical fix, not the default.
NIH Office of Dietary Supplements — Vitamin D →
Why UV 3–5 — and why sunlight at all
Sunlight is the body's main source of vitamin D — skin makes it directly from UVB, more efficiently than most food. Meaningful synthesis begins around UV Index 3, the same level WHO uses as its sun-protection threshold — a short dose in the 3–5 range gives real vitamin D without high burn risk.
It was even medicine before supplements existed: Niels Finsen won the 1903 Nobel Prize treating skin tuberculosis with concentrated light, and Auguste Rollier's Swiss heliotherapy clinics treated thousands of rickets and bone-tuberculosis patients with graduated sun exposure, decades before antibiotics.
Sources: WHO/WMO Global Solar UV Index report · Nobelprize.org (Finsen, 1903) · Rollier, Institute of Heliotherapy, Leysin
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Best time to run & walk outside
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Estimated airborne microplasticNOW
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Flight delay risk
Forecast available up to ~4 days ahead · time is local to the departure city
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☀️ Safe sun time for Vitamin D
🏃 Best time to run, walk & play outside
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