What are the temperature signs of whelping ?

As I'm sure you know, in 'old money', normal for the dog is 101F.   When under stress it can go to 102F and any higher means infection.  The temperature in the bitch will flucturate during the final days, but only when  it drops, perhaps to as low as 96F, and stays down, can you expect whelping to begin, perhaps within 48 hours.   Personally I don't put everything on the temperature although it is a guide.