Western Australia Surf Forecast by Craig Brokensha (issued Monday 19th December)

Best Days: Tuesday morning, Wednesday morning South West, Friday morning keen surfers, protected spots later Saturday and Sunday morning

Recap

Small clean waves across swell magnets in the South West Saturday with improving conditions as the offshore wind eased. To the north the surf was tiny, while Sunday saw choppy and onshore waves across all coasts.

Today started slow and bumpy at all locations but a strong new W/SW groundswell has since filled in, with good waves in protected spots across the South West, as shown in the screen grab.

We should see the South West reach 6-8ft this afternoon, with 2ft to occasionally 3ft sets in Perth later.

This week (Dec 20 - 23)

We should see this afternoon's building W/SW groundswell peaking this evening and then easing off through tomorrow but with offshore winds.

Margs should ease from 5-6ft with 2ft sets in Perth with fresh and gusty E/SE winds, strong from the S/SE into the afternoon in the South West, with sea breezes to the north.

Come Wednesday the swell should continue to ease under an E/NE tending N/NE breeze before sea breezes kick in. Head to swell magnets around Margs.

Some new small to moderate sized SW groundswell is due to build through Thursday with a secondary less consistent W/SW groundswell pulse for Friday.

These two swells have been generated by the same broad mid-latitude low currently north of Heard Island, with a weak pre-frontal fetch of strong W/NW winds, and slightly better trailing W/SW fetch.

A late onshore change on Wednesday looks to linger Thursday out of the S/SW spoiling the first small pulse, while Friday's increase looks to be met with better SE offshores.

Margs should build to 4-5ft+ with 1ft to nearly 2ft waves in Perth, but sea breezes will come up when it peaks through the afternoon.

This weekend onwards (Dec 24 onwards)

Friday's swell should ease back a touch into Saturday morning under S/SE winds, but later in the day a strong SW groundswell is due to fill in.

This will be produced by a very strong mid-latitude low forming north of Heard Island Wednesday, producing a fetch of severe-gale to storm-force W/SW winds through our south-western swell window.

A moderate to large and long-period SW groundswell is expected, arriving Saturday afternoon and reaching 8ft by dark in the South West and maybe 2ft in Perth. A drop in size is then due Sunday from 6-8ft and 2ft respectively with S/SE winds.

Longer term smaller swells with winds from the south are due next week, more on this Wednesday.