Thousands of residents throughout NSW have evacuated because of the major flood that swept regions later today particularly the Reiverina city of Wagga Wagga.

Latest forecasts regarding the Murrumbidge River have urged people coming from the northern and eastern part of the city to move out and transfer to emergency accommodation.

Some areas in Gundagai experienced flooding the whole night because of the Murrumbidgee River, which rose a meter higher than what was forecasted earlier.

According to the Mayor in Gundagai, Abb McAlister, this year's flooding is definitely worse than last year's.

The State Emergency Service (SES) predicted that the river could get much swollen at a level that is beyond what was predicted before if major dams continue to spill.

SES gave warnings for about 15 river valleys throughout NSW. SES said 70% of NSW was already flooded due to the constant rain.

People living in Uranquinty, Lockhart, Brindabella Valley, The Rock and Jugiong were also told to leave their properties and transfer to a safer place.

In some areas in Cowra, Yoogalie and Ungraie, people were also advised to evacuate. The Darling River is expected to create a major flooding today as it reaches 13.8 meters high.

A town in Forbes is on high alert as it prepares for the most raging flood since 1990.

Around 230 properties are expected to be abandoned today to avoid the major flood that may be created by the swollen Lachlan River.

Several other towns were isolated due to the constant rain such as Griffith, Narrandera and Leeton.

Wayne Roberts, SES deputy incident controller, said they're facing the challenge of convincing people to leave as many of them prefer to stay in their houses and protect their properties.

Around 300,000 sand bags were laid with the help of 900 volunteers to protect properties in the north-eastern part of the state.