The Spring weather outlook is out with the Northern Rivers looking likely to be wetter than normal with higher temperatures.

Today's picture perfect weather is an example of the warmer days and although we are predicted to get some rain in the next 7 days it is not the pattern expected for the rest of spring.

The Bureau of Meteorology has increased the chance of rainfall exceeding the average to 80% for most of NSW except for the mid to north coast which is slightly lower, so still a very good chance of some good rainfall as the weeks progress.

The average rainfall for Lismore for spring is 239 mm with November the wettest month.

The reason is due to ever increasing likelihood of a La Niña forming this year, the first since 2011/12. La Niña sees an increase in sea surface temperatures in the tropical Pacific and Indian oceans. The result of which is an earlier arrival of the northern wet season.

This predicted weather pattern is set to test the new $8.2 million Flood Mitigation Plan that is being undertaken in South Lismore and is due for completion in October, 2020.

In minor flooding the system does not change because the Leycester Creek banks have not been broken and the Hollingsworth Creek flood gates remain open. In the case of a major flood, more floodwater will flow behind South Lismore, ultimately re-joining the Wilson River at the airport. This should reduce the amount of water that would otherwise travel towards the CBD.

The modelling for the Flood Mitigation Plan anticipates a reduction in water of 100mm (10cm) in South Lismore, North Lismore and the CBD.

With La Niña is on our doorstep once again all the theory that has gone into reducing the chance of a major flood in Lismore reaching 2017 levels should be put to the test.

Hopefully, the mark is an A+.