Speaking at the Crop Updates in Perth late last month, Dr Stephens said confidence in early season rainfall was not as high as it was for the second half of the season.

"An El Nino should break down and neutral conditions should return in the eastern Pacific," Dr Stephens said.

"A review of analogue years suggests that average to above average rainfall and crop yields are likely for the southern Wheatbelt and average rainfall and yields are likely for the northern Wheatbelt.

"However, the confidence that we place in these forecasts is much greater in the south than in the north, and the reason for that is because we skill tested our forecast for all the years in the past up until last year.

"If an El Nino does persist, and there is a 20 per cent chance of that happening, we could have a much more negative scenario.

"The key thing is we will update our forecast once the May data comes in.

"Once we are in May, or the beginning of June, we will update our forecast, but we will keep with our existing forecast until that time.

"Finally, it is planned that we will be issuing crop yield forecasts into yield moisture, sowing dates, seasonal outlooks and satellite imagery, in products that we will deliver this year."

Dr Stephens said even if the current climate outlook looked promising, farmers should manage their cropping programs carefully on the basis of stored soil moisture, sowing opportunities and other information released in the department's AgTactics.

According to the Department's latest seasonal update, crop areas in WA in 2010, are expected to be heavily responsive to moisture conditions at planting.

"Grain price forecasts are not rising and growers are planning to maintain similar programs to 2009," the update said.

"However, a continuation of the long dry summer conditions into autumn could see progressive cutbacks in the area sown.

"Input costs will be lower than last year due to an easing in fertiliser prices.