Farmers and firefighters may be in for some much-needed rain relief by the end of this week with the potential for some good falls in drought-hit parts of the state.

While meteorologists caution that significant disagreement remains among the main weather models, coastal regions may be getting their best rain in weeks or longer.

The promising combination is a low-pressure trough moving across NSW and a high-pressure system that will set up in the Tasman Sea, Anita Pyne, a forecaster with the Bureau of Meteorology, said.

"The instability comes from the trough and the moist tropical air stream comes from the high pressure system," she said.