How cold is cold in Florida?

It has been a chilly week and our furnace hasn't been working but we "stuck"it out until our 2010 money went into our account. The repair man came and my worst fears came true the coils (both) are so pitted from the salt water attack of Hurricane Charlie(years ago) that they will no longer hold the reftigerant. To have central air we will need to replace the unit. The good news is the heater only required a transfer switch and is up and running. We will go"true old Florida" and be green with our open windows,fans,ice tea on the lani and skip the new air for this year. Bryce and Suria have been after us, all week, to come up to their warm house and enjoy the kids. Burton needed to teach Wednesday night at church and we needed to wait for Mr. Fix-it to get us up and running for the colder cold front that is on its way.  We are now in St. Petersburg having a wonderful time. I go to AVEDA tonight  and we may do Disney on Monday. Burton hopefully gets his bridge fixed (again )on Tuesday morning then back to Pine Island. We woke to sleet hittingthe roof this AM but the predicton for tonight is in the high 20's so I guess to answer the above question anything below 50 if your blood in thin :)