Front dooors not opening

I have a 98 Jetta that when it's really cold the front door won't open from the inside or outside.I have auto locks and the latches go up when I press unlock or use the key but the doors just won't open. I have to crawl into my car from the back seats. It's pretty embarrasing i think people figure I have OCD. But then when It gets a little warmer durring the day or something they open like there's no problem. Any help is so appreciated!