People forget that hot battery needs to charged at a lower rate, some of the drop is by design.
The recommended compensation is a 3mV drop per cell for every degree Celsius rise in temperature.
If the float voltage is set to 2.30V/cell at 25°C (77°F), the voltage should read 2.27V/cell at 35°C (95°F).
Going colder, the voltage should be 2.33V/cell at 15°C (59°F). These 10°C adjustments represent 30mV change.