My car doesn't like the cold

Last weekend, i purchased a 2005 Saab 9-3 linear. It is a nice looking car. It ran fine for the first few days (really Sat, Sun and Monday). Then Tuesday, i was out of work due to snow (yes, i live in the south and yes we close down for the slightest bit of wintry weather). Tuesday night i tried to run errands, but the car wouldn’t start. It wouldn’t even turn over. Knowing that it was the original battery in the car, we figured I had a dead battery. We hooked it up to a battery charger and the battery was low. We got the car started and the next day, I took it and got a new battery. The car ran fine on Wednesday and Thursday. Then Friday morning, the car wouldn’t start again, but it did start Friday afternoon. We drove it all Saturday with no problem. Then Sunday morning it wouldnt start again. At this point there seemed to be a pattern- cold weather, car wont start, but warmer weather and the car will do just fine. I hit google and got a bunch of hits suggesting the starter was faulty. Once the temps. got above freezing, I was able to get the car started again and got it to my mechanic.



It is now Monday and I just got a call from my mechanic saying the starter is fine (the checked the voltage on it). Any idea what is going on here?