Good comments by all, especially the description of what typically happens when a cold front passes across the Florida peninsula. The seven- to ten-day cycle is right on the money. After you've seen two or three fronts pass through, the pattern becomes readily apparent. On the Atlantic cost of Florida the first sign of an approaching cold front is the prevailing wind veering from east to southeast, then south and southwest It usually takes a couple of days. It's the change from SW to NW and then N as the front nears that is much faster and often accompanied by blustery winds and rain.
Cold fronts tend to be less severe after the first of the year, so you may want to postpone the Dry Tortugas until March when the weather is really nice and the anchorage offers better protection. Also, instead of trying to return to Key West against a strong headwind and waves, why not head for Ft. Myers instead (less than 20 hours) then take the Okeechobee Waterway back to Stuart?
Cold fronts tend to be less severe after the first of the year, so you may want to postpone the Dry Tortugas until March when the weather is really nice and the anchorage offers better protection. Also, instead of trying to return to Key West against a strong headwind and waves, why not head for Ft. Myers instead (less than 20 hours) then take the Okeechobee Waterway back to Stuart?