By Peter Hobson

CANBERRA, Sept 25 (Reuters) - Australia is on track to reap its third-biggest wheat harvest and its largest ever barley crop this year, according to a poll of analysts, many of whom have raised their estimates in recent weeks thanks to favourable crop conditions.

Australia is the world's No. 4 wheat exporter and a big shipper of other crops. Its large wheat harvest will add to plentiful global supplies that have driven benchmark Chicago futures to five-year lows. Wv1 GRA/

A poll of eight analysts in Australia released a median forecast for the country to produce 35.3 million metric tons of wheat, 14.7 million tons of barley and 6.45 million tons of canola in the harvest that will ramp up in the coming weeks.

For wheat, the forecast exceeds last season's production of 34.1 million tons and the five-year average of 33.8 million tons, though it remains below the record 40.5 million tons harvested in 2022/23.

Barley output is set to comfortably beat last year's harvest of 13.3 million tons and the five-year average of 13.4 million tons and edge ahead of the record-holding 14.6 million tons produced in 2020/21.

The canola forecast is a little above last season's 6.4 million tons and on par with the five-year average of 6.5 million tons.

"After a difficult start, the rain has been good in most cropping regions," said Michael Whitehead, executive director for food, beverage and agribusiness insights at ANZ.

"The indicators coming out of Western Australia look very positive, and problem areas elsewhere look better than they were last year."

Five of the analysts polled by Reuters were also asked for their numbers a month ago. On average, they had raised their estimates for Australian wheat production by 1.7 million tons.

That said, rain has dried up in parts of eastern Australia, injecting caution into the outlook.

"October rainfall will be critical through southern New South Wales and large parts of Victoria and South Australia to stop crop potential from going backwards," said Rod Baker, an analyst at Australian Crop Forecasters.

Harvesting will wrap up around the end of the year.

Following are analyst estimates in millions of metric tons.

(Reporting by Peter Hobson; Editing by Naveen Thukral)

((peter.hobson@thomsonreuters.com;))