Hey my dog had puppies and a few of them have runny noses.. what could it be? Is it because of weather changes hot/cold...

It could be upper respitory. You should be consulting a vet. Infants crash and burn fast!

There shouldn't be any weather changes.
Pups up to 2 weeks need to be kept at a constant temperature with a heat lamp.

Time for a visit to the vet with these little ones. It's time for their first worming treatment anyway.

Get to a vet fast. Little ones get sick and die quickly.