Holy Extrapolation Batman! Or, "We can estimate, using data from extant high-speed rail networks." I think you'll find that HSR generally has good on-time performance where it is not forced to share lines with freight trains (ie, not Amtrak). Since there are no mag-lev freight trains, and no plans to build any, it's reasonable to think that mag-lev trains would only be affected by weather in very extreme circumstances (not your run of the mill snow storm).