The 737 is available with or without aspirated TAT probe. If you have the unaspirated one your TAT before takeoff will creep up within 2 or 3 minutes to 99°C (and more, but that isn't displayed) after probe heat is switched on, invalidating any data based on that. Even the aspirated probe is often considerably off the real OAT, depending on position vs. the sun and other factors.