"There was a... cold snap, earlier in the week."

It's a little bit obvious when Will is lying about something. He is just not very good about it, but in this case he is not completely lying, merely omitting some details. There's still the same sort of breathiness to the assertion, however, a lack of total conviction.

"It was really strange." And he shrugs, as if to dismiss the issue. "What is it you do, Julien?"