"Inclement"

When:

Lookups spiked on February 1, 2011.

Why:

News reports about "inclement weather" heralded a major snowstorm in the midwest and northeast of the U.S.

Inclement means "stormy." Its Latin root clemens means "mild" or "calm" – so inclement is the opposite of that.

(The related word clemency means "mercy" or "compassion.")