Data Source

Weather data (temperature and relative humidity) is fetched hourly from Open-Meteo API for locations across India.

Grid Resolution

The map uses a 0.25° latitude/longitude grid (~28 km spacing) covering India. Only grid points within India's boundaries are included.

EHI-N* Calculation

For each location, the Extended Heat Index (EHI-N*) is computed using pre-calculated lookup tables derived from the two-node human thermal model. The "N" denotes the MET level (metabolic rate) and "*" indicates additional solar radiation heat stress is applied. The calculation assumes:

• MET level: Selectable (3-6 MET, default MET 6 for heavy work)
• Sun exposure: Selectable (shade or sun, where * applies additional heat stress)
• Standard adult physiology

Physiological Zones

EHI-N* values are mapped to physiological zones based on thermoregulatory limits:

• Zone 1: Cold stress (below comfort range)
• Zone 2: Comfortable (thermal equilibrium maintained)
• Zone 3: Mild heat stress
• Zone 4: Caution (approaching thermal limits)
• Zone 5: High Risk (thermal strain, limited work capacity)
• Zone 6: Hazardous (hyperthermia risk, hazardous conditions)

Update Frequency

Data is automatically updated every hour via GitHub Actions.