Western Australia Surf Forecast by Craig Brokensha (issued Monday 8th September)

Best Days: Perth and Gero Thursday morning, all coasts Friday morning, Saturday and Sunday

Recap

The weekend was poor with strong onshore winds and building levels of swell which have become large into today. There's no respite until Thursday but read on for more details.

This week (Sep 9 - 12)

Today's large swell will be supercharged into tomorrow by a vigorous frontal system that's currently slamming into the state. A fetch of severe-gale to sub-storm-force W/SW winds are whipping up a very large swell that should peak tomorrow in the stormy 15ft range in the South West, 4-6ft in Perth and 8-10ft up at Gero.

Conditions will be terrible though with fresh and gusty W/SW winds that will swing more W'ly through the day.

A drop in size is due into the afternoon and further Wednesday, but a secondary vigorous front racing in quickly behind this evening's system will stop the swell dropping further into Wednesday afternoon, providing another large pulse.

The South West should hold in the 10-12ft range with 3-4ft sets in Perth and 6-8ft+ surf up at Gero before easing slowly into Thursday. Winds will remain onshore through the morning from the W/SW but weaken considerably during the afternoon creating improving conditions.

Thursday will be the day to surf though with winds tending variable and light offshore from the E across Perth, E/SE up at Gero while Margs is looking a little dicey with linger NW winds unfortunately. Margs should ease from 8-10ft+ with 3-4ft sets in Perth and 6ft to possibly 8ft sets early around Gero.

The swell will continue to ease into Friday with more variable winds likely around Margs creating better conditions, while Gero and Perth should see morning SE winds.

This weekend onwards (Sep 13 onwards)

We're looking at a very strong, powerful long-period W/SW groundswell arriving through Saturday and peaking during the afternoon across the coast.

This will be generated by a very strong polar low firing up south-east of Madagascar under the influence of a strong node of the Long Wave Trough.

A slow moving fetch of severe-gale to storm-force W/SW winds will be aimed towards us, generating an open ocean swell up to nearly 60ft north of Heard Island.

The extremely strong core wind speeds will generate a powerful long-period swell with forerunners in the 22-24s range, arriving through Friday evening and peaking Saturday afternoon to 10-12ft at exposed spots in Margs with 15ft+ sets at offshore reefs and bommies.

Perth should build to 3-5ft, with Gero increasing to 8ft+.

Winds will be OK but not great and from the SE tending S'th in the South West and from the S/SE further north. Sunday looks great though with offshore winds ahead of sea breeze, but we'll confirm this Wednesday.