The Irish sailor has relished the windy conditions using her strength to her advantage and finished ahead of Great Britain's Alison Young in both races by eight seconds in Race 3 and 30 seconds in the fourth race.
On her start Murphy said, "It can't get much better than winning the first four races but there's still six fleet races left so it's going to be really tough. All of the girls are really good and I think I've had a bit of luck and things have gone my way but that doesn't always happen in sailing."
With further big winds predicted throughout the week Murphy, who is one of the best big wind Laser Radial sailors, is taking it day by day, "I'm trying not to look at the forecast," said Murphy. "We've got a forecast guy and he tells us in the morning what's going to happen. I don't want to think about it too much but if you start speculating on the forecast you're just going to get obsessed with what could happen."
Young clawed herself back into contention for the medals today with two seconds having had a shaky start to the regatta. She takes 21 points into the third day of racing and will want to put in a similar performance to overcome Marit Bouwmeester (NED) who's third on 18 points and Van Acker, second on 16.
The Radials resume racing tomorrow at 12:00 local time on the Weymouth Bay West course.
Follow all the action on the ISAF Olympic Live Blog which will bring competition updates and instant reactions to the action on the race course. Fans can check in and ask our media team questions to get the very latest information. The blog will start one hour before racing each and every day of the competition.
ISAF Olympic Website