Dairy prices at Fonterra's latest online auction rose almost 2%.
The average selling price for all products rose 1.9%, to $US3663 per tonne.
Dairy prices have been volatile in recent months.
Prices jumped 17% at the last auction, a fortnight ago, but fell in the four months before that.
Whole milk powder rose 1.4% at the latest auction.
Last month, Fonterra left its forecast milk payout for the season unchanged at $6.90 - $7.10 per kg of milk solids, saying there were signs prices would improve later in the year.
Wednesday night's auction was the first mid-month sale following a decision by Fonterra to increase the auctions from once to twice per month.