Storms to bring a month's rain to many parts of NSW

The heavy rain could last for several days as it slowly moves south through NSW, putting harvest on hold, and leaving farmers hoping unharvested crops survive the heavy rain without loss to yields or quality.

There are not many places in the middle of NSW that will not get over 50mm rain by Friday.

The flood warnings are extensive but the greatest focus is on northern rivers such as the Gwydir, Upper McIntyre, Peel and Namoi Rivers and further south major flood warnings for sections of the Macquarie and Lachlan rivers.

Some storms could bring over 150mm, the Bureau warned.

The Bureau of Meteorology issued numerous flood warnings late on Tuesday:

Wilsons River minor flooding

Richmond River minor flooding

Orara River minor flooding

Bellinger and Kalang Rivers minor flooding

Nambucca River minor flooding

Manning and Gloucester Rivers minor flooding

Upper Macintyre River moderate to major flooding

Gwydir River moderate to major flooding

Whalan and Gil Gil Creeks(Local Flooding)

Peel River moderate to major flooding

Namoi River moderate to major flooding

Castlereagh River moderate flooding

Macquarie River to Bathurst minor to moderate flooding

Orange, Molong and Bell River minor to moderate flooding

Lachlan River to Cotton's Weir minor to major flooding

Belubula River moderate to major flooding

Mandagery Creek minor to major flooding

Lower Lachlan River minor to major flooding

Tumut River minor flooding

Upper Murrumbidgee River to Burrinjuck Dam and Cooma Ck minor flooding

Murrumbidgee River to Wagga Wagga minor flooding

Queanbeyan and Molonglo Rivers minor flooding

Barwon River minor flooding

"Wet and stormy weather will redevelop over much of New South Wales from Wednesday, as a deep low pressure system interacts with very humid tropical air," the Bureau said.

Also read: Mixed blessings for grains industry in late season La Nina

"Widespread rainfall across NSW is expected through the second half of the week. Very intense rainfall rates are likely for some areas, most likely over the north from late Wednesday. The heaviest rainfall is forecast to contract to the south east of the state through the weekend as the low moves offshore.

"The weather system is expected to cause flooding for the catchments listed from late Wednesday into the weekend. Flood classes are only defined for catchments where the Bureau provides a flood warning service."

Nearly all major dam catchments are full or close to full in NSW: northern storages are 84 per cent full, central storages are 91pc full, and southern storages are 94pc full as of Wednesday.

The harvest has proceeded well so far although protein levels are reported to be down for wheat but yields have been high with canola going 3tonnes/hectare in some areas and cereal grains 7-8t/ha.

Many farmers will take advantage of the rain and double crop after the rain and go straight into a summer crop of corn or sorghum in the northern crop areas.

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