The 22-year-old Swede had nine birdies and one bogey at the season-ending tournament and leads Laura Davies and Lisa Hall by three strokes. Sophie Gustafson (68) is tied for fourth with Lisa Holm Sorensen.
Defending champion Annika Sorenstam, who held the previous course record of 65, shot a 2-under 70 and was tied for ninth place.
Stahle, who was born the same year Davies turned professional in 1985, birdied her first four holes.
'Annika and Laura are players whom I have always looked up to, so it's just great to be ahead of them,' Stahle said. 'But I do not want to get ahead of myself. This was just the first round and a lot can happen in the next three days.
'I was on a roll today and hopefully I can continue in the same manner.'
Sorenstam, looking for her first win of the season after being hampered by neck and back injurie early in the year, birdied her last two holes.
'I drove it well and I feel good on this golf course. It suits my game very well,' Sorenstam said. 'I missed just three greens, but I could not make my up-and-downs from there. I've just got to stay away from mistakes and things should be fine.'
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