How long w/no eggs?

I have two showgirl hens - They had just started laying and I was getting 2 eggs per day most days, for maybe 5 weeks before the cold weather (see note below) & rain hit. Now they haven't laid even one egg in ... at least 3-4 weeks. Although they *can* freerange during most days, they don't. They prefer to be in the run and coop while the other (bigger) hens run around the yard.

NOTE: Keep in mind ... I am in Southern California, so it's not THAT cold LOL ... in the mornings, we've got frost on the grass, but it's been up in the high 60's low 70's during the day... The "rainy season" was about 4 days. (Sorry all you folks w/snow & such!!!)

How long can or do they go without laying in the winter? I know I could "encourage" production with light and/or heat, but wanted Mother Nature to be the guide. Just wondering when to get worried...

Thanks!!