THI data logger update 10-16 August 2026. The…

THI data logger update 10-16 August 2026.

The heat certainly came back last Weds/Thurs/Fri across GB hitting average 24hr THIs of 68-75, region depending. The south and Midlands bore the brunt yet again spending the entire week at average THIs of 66-75 offering no real relief for cows in terms of fertility impacts.

Hours above THI 67 when cows alter lying times were severely impacted on the peak three days of heat with 84%, 82%, 71% and 69% of all hours above this threshold on the W/T/F days for the south, Midlands, Wales and northern England respectively and Scotland, whilst being less severe, also managed 40% of all hours above THI 67.

Highest THI came from the highest temperature I have observed in 6yrs as THI 88 was recorded in our shed in Dorset with 41.2°C (previous high 40.4°C in 2022) @ 25% RH (we saw a higher THI of 91 in June this year from lower temp and higher RH) which shows how extreme it was and impact of sun on temp and RH.

This week is thankfully cooler but the impact of last week will take weeks/months to fully correct 🐄☀️🌡️

Originally posted on Facebook · Tuesday 18 August 2026, 15:55 · View original →