Critical temperatures:
125 F — No action needed
150 F — Hay is entering the danger zone. Check temperature twice daily and disassemble stacked hay bales to promote air circulation to cool the hay.
160 F — Hay has reached danger zone. Check temperature every couple hours and disassemble stacked hay.
175 F — Hot spots or fire pockets are likely. Alert fire services; stop all air movement around hay.
190 F — With fire service assistance, remove hot hay. Be aware that hay could burst into flames.
200 F or higher — With fire service assistance, remove hot hay. Most likely a fire will occur; Be aware that hay could burst into flames.