I set my tyre pressures for the season, in the morning summer at ambient temp of about 15c to 20 c. Winter temps between 5 and 10 c.
The Tyre pal on my caravan, will show temp will rise about 9⁰c above ambient temp and the pressures will rise about 6 to 7 psi above initial setting.
ie. Tyre pressures at cold 65psi @20⁰c will rise to 71psi and 29⁰c