Here is a link which explains the temperature method in detail. Her entire site is very informative so read this article and then read all she has to offer. Like another poster mentioned it is in fahrenheit so you will have to do some conversion, but a rise followed by a drop is what you are looking for. Good luck, prayers for a safe and easy delivery.
Canine Reproduction Video and Book on Breeding and Whelping dogs by Debbie Jensen for dog breeders and Whelping Supplies needed to deliver puppies.