"It was a bit windy at the beginning of the match and he's extremely accurate with his returns.
"It's tough in those situations.
"Ideally, I'd have played that next game and then held and then we'd have had the break.
"But I like playing indoors.
"I grew up in Scotland; the weather is not quite like here."
Murray's triumph completed a great day for British tennis, with older brother Jamie booking a spot in the last four of the men's doubles and Johanna Konta advancing to the women's semi-finals.
The second-seeded Murray has reached the last four at five of the past six Australian Opens, but has yet to win the title.
The Scot has beaten Ferrer in four of their five clashes at grand slam level.
The Spaniard came into the latest encounter as the only man yet to drop a set at Melbourne Park this year.
That record lasted all of one set, with Murray breaking in the fourth game and saving two break back points in the ninth game before going on to clinch it 6-3.
But the Spanish ironman was never going to go away quietly, playing the big points better in the tiebreak to level at one set all.
The final two sets were largely one-way traffic - outdoors and then indoors.
The big-serving Raonic continued his run of red-hot form with his impressive win over Monfils.
Raonic remains unbeaten in 2016 after accounting for the Frenchman 6-3 3-6 6-3 6-4 on Rod Laver Arena in two hours and 17 minutes.
His impressive run at the Open follows on from his Brisbane International final win over Swiss master Roger Federer.
"It's a great challenge ahead of me - a challenge that I believe I have within myself to find the solution to," Raonic said of facing Murray.
"It's (going to be) a great fight that I'm going to put out there with all my heart, all my effort, and hopefully I can make the most of the opportunity."
Raonic will meet Murray in his first semi-final at Melbourne Park - a mark he has reached once before at Wimbledon in 2014 - and will be looking to make it into his first grand slam final.
Today:
Men's semi
Novak Djokovic [1] v Roger Federer [3]
Women's semis
Serena Williams [1] v Agnieszka Radwanska [4]
Angelique Kerber [7] v Johanna Konta
- AAP