We really don't have a set policy for snow days or inclement weather. We can't really say something like "If the schools are cancelled, so is curling" because the roads are sometimes a lot better at night than they were in the morning, or vice versa.
What we have done in the past is have the league coordinator speak with a few of the skips on the day of the storm to poll them on whether they think it's a go or not. The skips can then call their teams and advise accordingly. I know it's not perfect, especially for people driving and/or boating from a distance, but it has worked pretty well in the past.
(In past years Open Day curling was cancelled if the Falmouth schools are closed due to snow)