Brenda,

Not to worry. Here in Nova Scotia, we barely had any snow last year. We actually only had one snow storm which closed the schools, and normally there's at least 5 'snow' days. Our 2005/2006 winter was the warmest on record, but we still had some chills in February and March!

If your soil in the containers is about 3" deep and you've soaked it before sowing the seeds, there won't be any need to start watering - or even checking for watering - until the weather starts warming up. Just make sure you have holes in the top for the rain and the snow to get in. If you are doing the 2 liter pop bottles, the cap being off is sufficient.

Welcome to winter sowing and many successes!

Brenda you are probably close to me, even though we haven't had the snow we have had lots of rain, so them drying out shouldn't be a problem
Good Luck