Our last frost date here is May 15-17, so I don't know why I'm so surprised at this:
National Weather Service Zone - OHZ015
URGENT - WEATHER MESSAGE
NATIONAL WEATHER SERVICE NORTHERN INDIANA
914 PM EDT THU MAY 17 2007
AREAS OF FROST EXPECTED ACROSS THE REGION OVERNIGHT...
A FROST ADVISORY REMAINS IN EFFECT FROM 2 AM EDT /1 AM CDT/ TO
8 AM EDT /7 AM CDT/ FRIDAY.
A FROST ADVISORY MEANS THAT FROST IS POSSIBLE. THOSE SENSITIVE OUTDOOR PLANTS MAY BE KILLED IF LEFT UNCOVERED.
This, after tying the record high just two days ago, at 91° F.
We covered the amaryllis that I planted out last week and brought in the brugmansias, rex begonias, Boston fern, verbena, and orchids. The pelargoniums that I have on the front porch will be fine, I think. They're in a corner, up against the brick, which retains the heat of the day for awhile. I don't know what else might suffer any damage from the impending frost, but whatever will be will have to be. There's no way I can cover everything.
Maybe we'll get lucky and avoid the frost altogether. *crosses fingers*
The sun was warm but the wind was chill.
You know how it is with an April day
When the sun is out and the wind is still,
You're one month on in the middle of May.
But if you so much as dare to speak,
A cloud comes over the sunlit arch,
A wind comes off a frozen peak,
And you're two months back in the middle of March.
- Robert Frost
EDIT: While we had a light frost and it was quite patchy, nothing was harmed. We had the same situation the next night, with the same good results. YAY!