A little after 8 p.m. ET Sunday, a squall with winds of 14 knots hit the flotilla and stayed "nearly stationary over" Nyad, forcing her to move northwest in order to try to find a way out of the storm.
"Big thunderstorm came out of nowhere last night, but good news is there were no signs of jellyfish," Nyad's team tweeted this morning.
Despite a body suit designed to give her protection from jellyfish, Nyad has already been stung at least four times as she attempts to complete the 103-mile swim from Havana to the Florida Keys.
After a stormy night, Nyad's team blogged this morning that conditions are spectacular.
"Seas are calm and Diana is swimming strong at 50 strokes per minute and has swum 33.81 statute miles," Angie Sollinger, part of Nyad's media team, wrote. "There have been no jellyfish sightings our experts report. Beautiful out!"
As of Monday evening, Nyad has swam "a little over 40 miles."
Nyad jumped into the water late Saturday night. At a pace of 50 strokes a minute, the journey should take about 60 hours. If she succeeds, her team says, she will finish on Tuesday or Wednesday. If she finishes on Wednesday, it will be her 63rd birthday.
It is Nyad's third attempt to complete the swim in less than a year. For the record to count, she is not allowed to touch or be touched by any of the support crews or vessels. She is also not allowed to sleep while trying to make the swim.
Nyad ended her last attempt in September 2011 after more than 40 hours, 67 nautical miles of swimming, and two Portuguese Man-of-War stings.
"The medical team said I should not go another two nights in the water and risk additional likely Man-of-War stings which could have a long term cumulative effect on my body. But for each of us, isn't life about determining your own finish line? This journey has always been about reaching your own other shore no matter what it is, and that dream continues," Nyad called out to her flotilla of four escort boats from the water, according to her website at the time.
ABC News' Matt Gutman and Leezel Tanglao contributed to this report.