What is too cold?

Well I am doing an 1/2 marathon on this Sunday. As a reminder I am a Florida gal.
The lows that AM are supposed to be mid to high 30's and highs low 50s.
So the 50s and sunny for a 1/2 marathon are OK. But the cold start AND the fact you have to be out there in the environment for 1 or 1.5 hours (at a minimum) before...brrrr. My feet/toes are ALWAYS numb before I start. AND I have learned to wear layers and "check gear". But that temp for a race start is too cold for this Florida chic!! I would prefer a 40-50 start and 60 for a high!!!

K