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Heat stress (THI) tracker
See the temperature-humidity index for your province over the next 7 days and what to do on hot days.
Main dairy regions
Choose a location
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How it works
Pick a province: the page fetches a 7-day hourly forecast of temperature and humidity and calculates the temperature-humidity index (THI) for dairy cows.
Next 7 days · daily maximum THI
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Hours at or above THI 68 (stress threshold): –
Stress levels for dairy cows
| THI | Level | What happens |
|---|---|---|
| < 68 | No stress | Normal intake and yield. |
| 68–71 | Mild | Breathing rate rises; high-yielding cows start to lose milk. |
| 72–79 | Moderate | Lower intake and milk, more standing, lower conception. |
| 80–89 | Severe | Clear drop in milk and fertility; acidosis risk increases. |
| ≥ 90 | Danger | Risk of death, especially without shade and cooling. |
THI = (1.8·T + 32) − (0.55 − 0.0055·RH)·(1.8·T − 26), with T in °C and RH in %. Threshold of 68 for high-yielding cows after Zimbelman et al. (2009).
Quick calculator
°C
%
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Weather data: Open-Meteo forecast (open-meteo.com). Your browser requests the forecast directly for the location you choose; no data is stored on this site.
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