Thanks for all the suggestions, everyone. :-) According to the data report,
I'm seeing that the temp hit 32 at the 4am hour (briefly hitting 31), and
stayed there for two hours before climbing again. By noon it was in the 50s
again... so we'll can only wait and see if it had any effect.

(FWIW, in the States you can get your local weather history [including
dewpoint] for the past 2 days by going to www.noaa.gov, typing in your zip code
and clicking on "2 day history").