Eighty-six degrees -- minimum. Eight knots of wind or fewer. If anyone understands the importance of pinpointing precise weather conditions, it's Diana Nyad and her 30-person crew.
Considered one of the best long-distance swimmers on the globe back when she was in her 20s, Nyad was just 28 when she endeavored -- and failed -- the dramatic 103-mile swim across the Gulf Stream from Havana, Cuba, to Key West, Fla.
The water temperature when Nyad's crew called her out of the water that day in August 1978 was 85 degrees -- balmy for a dip, but hypothermia-inducing after more than 24 hours in the ocean.
The winds had blown as much as 18 knots, producing nauseatingly high waves and pushing the crew too far west -- on track for Texas, not Florida. Nyad had swum for 42 hours when her team pulled the plug.
Sure, she'd had other feats -- a record-breaking time circling Manhattan Island, a distance record of -- count 'em -- 102.5 miles from Bimini Island in the Bahamas to Florida. It was on the beach following that swim, on her 30th birthday, that Nyad took off her swim cap and retired from the sport.
And for nearly 30 years she stayed retired.
"I can't think of a dollar amount what would take to have me swim laps again," she said in 2008 to a reporter at KCRW, the public radio affiliate where, when she's not swimming, she hosts her own weekly sports segment. "Talk to me when I'm in my 90s."
And she believed she wouldn't swim again until the moment she started swimming again. It came just before Nyad's 60th birthday. The death of her 82-year-old mother was a startling glimpse at her own mortality, and Nyad decided the remedy was to commit to something that would take every ounce of her being.
"It happened in a heartbeat," she said of this two-year, half-a-million-dollar endeavor. "I was driving in my car and I looked up in the rear-view mirror and caught a glance of my eyes in the mirror, and I thought, 'Would I? Could I?'"
If the disappointment of Nyad's youthful attempt at the swim taught her the importance of weather patterns, the summer of 2010 taught the importance of carpe diem.
In July of 2010, a year after that rear-view-mirror moment, the full crew set out for one last practice swim -- a whopping 24 hours long. The weather couldn't have been much more perfect -- the water glassy and warm, the winds still. But it was actually their last window for the summer. Hurricane season came shortly thereafter, and Nyad was forced to delay her dream until 2011.
Eternally optimistic, members of the crew all repeat the same refrain: "It's better this way."
Last summer's 24-hour dress rehearsal taught them valuable lessons that would guide the ultimate swim, anticipated to be around 60 hours.
They figured out how to rig up a boom that extends out the side of the boat to dangle a makeshift lane-line to guide Nyad in the water and built a displaced steering wheel for the boat that allows the driver a better view of his swimming charge.
They figured out the logistics of the boats that will make up Nyad's caravan; unlike her 1978 swim, Nyad won't be enveloped in a shark cage, but will be surrounded, in addition to the main boat, by two kayakers trained to divert sharks should the shark repelling radar on all three boats prove insufficient. And above all, Nyad herself is another year stronger and another year hungrier.
Now all that's left is the weather. They're looking for the doldrums. Dragging with it negative connotations of stuffy stagnation on land, at sea, this type of weather -- typical in July -- means the humidity is so heavy that it presses the water into a glass-like state.
And so the training is done and the team assembled, but it's the weather radar that holds the trump card.