I'm not a breeder but it has been said by breeders that normal temp. should be 100-103 degrees farenheit and when it drops down to 98-99 degrees, the female will probably give birth within 12-24 hours.
Puppy Pawz is correct. Average temp is around 101/102. I learnt that from my vet when I took Max in for a check up lol ;P I don't know the exact temp for a birthing bitch but when it drops drastically you know she's gonna give birth.
Just keep in mind every bitch is different. I have had them whelp as high as 99 or as low as 97.1 just keep a close eye on her and look for the other signs. Nesting, and right before she will go potty a lot to evacuate everything in her digestive system. Good luck.
Every bitch is different, like stated above. With my husky, her temp dropped to around 97 and then went back up the next day and didn't drop again until a week later, and she had pups that night.
Good luck, and some advice:
When you are taking your bitches temp when she is close to the due date. Try to take it around the same time every day, and write it down. I took my bitches around 1:30 pm every day until the day she whelped. That way they usually have a routine and it should stay pretty constant.