Frost on the pumpkins: first big frost of the year is this week

(Photo by Christopher Furlong/Getty Images)

It's been 170 days since it was as cold as we're expected to drop Monday night. But it's back.

Starting late Monday and into early Tuesday the low temperature will fall to only a couple ticks above freezing. Detroit will be about 34; outer suburbs may be near 31.  Burrr.

The first frost is an important one around here; it matters to farmers, gardeners and allergy suffers (who are probably thankful for the first frost).

Frost forms when the water vapor in the atmosphere lands on a surface and then freezes. This time of year, when there is still a bit of the Summer moisture in the atmosphere AND temps can drop to near or below freezing means that frost begins to creep into our daily lives.

While some spots did see a little frost early Sunday, the majority of us are likely to wake up to it Tuesday. This means bring in the delicate plants (or cover them) and make sure the animals don't get locked outside.

I'd love to tell you that after this one, we won't see another one for a while... but that's not true. In fact, it could be as early as Thursday when another frost forms. 

Sigh. Oh well. It's that time of the year.