Fonterra has revised its 2023 forecast earnings guidance to 45 to 60 cents per share, up from 30 to 45 cents per share, due to ongoing strong demand for dairy.

It has also revised its forecast milk collections for the 2022/23 season down from 1,510 million kg of milksolids to 1,495 million kgMS due to wet weather.

Chief executive Miles Hurrell said the lift in forecast earnings was a continuation of the ongoing strong demand for dairy that saw Fonterra confirm that its 2022 earnings were at the top end of the 25 to 35c guidance range.

"The demand signals we saw at the end of full year 2022 (to July 31) have continued driving improved prices and higher margins across our portfolio of non-reference products, particularly in cheese and our protein products such as casein," he said.

"We see strong underlying demand and the latest lift in whole milk powder prices on Global Dairy Trade is also a positive signal reversing the recent easing in the prices that drive our farmgate milk price," he said.

"Strong offshore prices for protein, as reflected in the recent increase in EU and US milk prices, mean our protein portfolio has been performing very well," he said.

"This sustained period of favourable pricing relativities between our protein and cheese portfolios and whole milk powder is the main driver for the increase in the 2023 earnings guidance range being announced today," Hurrell said.

"If these unprecedented conditions were to continue for a further extended period, this could have an additional positive impact on forecast earnings."

Hurrell said the co-op had recently seen a reduction in milk collections with weather conditions experienced in some parts of New Zealand causing a slow start to the season, most recently the floods in the Far North and top part of the South Island.

The co-op last month revised down its 2022/23 forecast Farmgate milk price range from $8.75-$10.25 per kg to $8.50-$10.00 per kg, reducing the midpoint from $9.50 to $9.25.

Fonterra will release its financial results for the year on September 22.

The co-op's NZX-listed units last traded at $3.10, up 10c from Thursday's close.