How cold before need to winterize?

[nipper]

It is supposed to get down to 33 degrees here in Indianapolis tonight, plus or minus a degree or few. I have a 1991 v20 cuddy with I/O. With temp. at/around 33 degrees, there may be a frost, but I would not think a "hard freeze." Should I be scrambling to get her winterized? Supposed to be in the upper 60's over the weekend and I would like to get her out for one last run down on the Ohio River.