A band of rain and thunderstorms will sweep across NSW at the end of this week, delivering the best falls in 4-5 months for some areas. October has already been a good month in terms of rainfall for some parts of the state, while others have missed out on a decent drop so far. Many areas in northern NSW have already exceeded their monthly average rainfall totals for October. Some parts of the northern coast and ranges and the North West Slopes and Plains have even doubled their October averages. Inverell and Yamba had both received around 150mm of rain so far this month as of 9am today. This is well above their long-term October monthly averages of 75mm and 78mm, respectively. It's also the highest October rainfall total at Yamba in seven years and Inverell since 1999. By contrast, mid-spring rainfall has been lacking in other parts of the state. Some central and southern regions of NSW have received less than 20 per cent of their average October totals so far this month. Deniliquin has only picked up 6.2mm of rain so far this month, which is less than one fifth of its long-term October average. This follows on from the town's equal second driest start to spring in 45 years, with a meagre 4.8mm recorded in the gauge during September. Sydney has only picked up 0.4mm of rain since the start of September, which makes this the driest spring to date on record for capital city. Fortunately, the rain-bearing system crossing NSW on Thursday and Friday will affect the almost every part of the state. Widespread falls of 10-20mm are likely and some areas could receive 30-50mm, possibly more with thunderstorms. Some parched parts of central and southern NSW should see their best rain since autumn before the weekend.