Weather data used for PMI includes which elements?

• A. Humidity levels only
• B. Daily temperature highs/lows and precipitation
• C. Wind speed only
• D. Atmospheric pressure only

Answer: (B)

Understanding PMI estimation hinges on environmental conditions that influence decomposition rates. Temperature history is the dominant factor; body decay speeds up at higher temperatures and slows in cooler conditions. Having daily highs and lows provides a practical record of the thermal exposure the body experienced, which is used in forensic models to align observed decay with time since death. Precipitation matters because moisture from rain or humidity affects moisture content, microbial activity, and insect colonization—factors that change the pace of decomposition. Recording precipitation totals complements temperature data to improve PMI estimates.

Humidity, wind, or atmospheric pressure alone don’t capture the combined thermal and moisture context that drives decay in most PMI models, so they’re not used as the sole weather data.