The race committee managed to run one of the scheduled two races for the world title chasers in the gold fleet, before the visibility became too poor and the windsurfers were sent ashore to wait for the fog to clear before the second race was able to get underway.
Amid the gloomy conditions there was plenty of drama, with the series leaders in the men's fleet picking up some big scores as they struggled to adjust to the change in conditions. Brazil's 2007 World Champion Ricardo Santos was hit hard, dropping from third place overall before the rest day, to 13th after finishing his two races on Tuesday in 44th and 45th.
The Dutch duo of Dorian Van Rijsselberge - the overall series leader at the halfway stage - and 2006 World Champion Casper Bouman also struggled to get off the startline, dropping five places each in the overall standings to sixth for Van Rijsselberge and 11th for Bouman.
Meanwhile Skandia Team GBR's Nick Dempsey - the 2007 World Championship bronze medallist - held fast and advanced to the top spot on the leaderboard, discarding his worst series score of 13th from the first race of the day and picking up a hard-fought third in the second race.
"It was pretty exhausting out there. It was just so hard to hold a lane in that first race, but then I think sailed a near-perfect second race," the 29-year-old surmised.
"It could yet turn out to be a week for the all-rounders," Dempsey hoped.
In the women's fleet, the Spanish dominance was rattled by Poland's Agata Brygola on this fourth day of racing at the championships. The Pole revelled in the lighter airs, scoring 2, 1 in her two races to boost her into second place overall, splitting the leading Spanish riders.
Marina Alabau's (ESP) clean sweep of race wins came to an end on Tuesday with 6, 8 on the scoreboard today, although she is still leading the championship by seven points over Brygola, with European silver medallist Blanca Manchon (ESP) in third with 8, 3.
Two 12th places for Skandia Team GBR's Bryony Shaw helped her advance one spot in the overall standings to eighth.
Racing at the 2009 RS:X Windsurfing World Championships continues on Wednesday with the final Medal Races held on Thursday 10 September.
Results - click here
Click here for our RS:X World Championships page containing all the news, photos, links to live results and more from this year's RS:X Worlds.
The RS:X World Windsurfing Championships is the second of three back-to-back World Class events being run by the RYA, supported by UK Sport, and hosted at WPNSA. The IWA Junior, Youth and Masters Windsurfing Worlds was held from 22-29 August, with the Skandia Sail for Gold Regatta - the final round of the 2009 ISAF Sailing World Cup series - set to welcome the cream of the World's Olympic Classes sailors from 14-19 September.