Snow won't trip your breaker unless you've got it on a ground fault circuit interrupter. Extreme cold will make the heater's nichrome draw a lot more current to start, but that should settle down after a few minutes. Repeated near-limit strain on a breaker will weaken it to trip at less current than rated.

The donut seal gets stiff; it will sometimes weep a bit in the worst cold, but live fine the rest of the year. You could replace it, but unless you're losing ounces or more, it will probably make it until the weather is conducive to pull the pump at leisure.
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Art Benstein near Baltimore