Bali and Mentawais forecast​​​​​​ by Craig Brokensha (issued Thursday 29th September)

Best Days: Bali Friday and Saturday, Sunday afternoon onwards for experienced surfers, Ments from Sunday

This week and next (Sep 30 – Oct 7)

Bali: Some new S/SW groundswell should be breaking across the coast today, with a further pulse later today and tomorrow morning to 6ft+ across exposed breaks. The surf will ease through the afternoon and further Saturday from 4-5ft.

Sunday is expected to start tiny, but into the afternoon our inconsistent SW groundswell is due to arrive, produced by a vigorous mid-latitude front firing up south-east of Madagascar.

The mid-latitude frontal progression linked to this swell has since pushed east towards WA with strength, producing a secondary larger pulse of S/SW groundswell that's due to fill in Monday. A third more southerly S/SW groundswell is then due Tuesday afternoon from a final fetch of severe-gale SW winds projecting into Margaret River tomorrow evening and Saturday.

Size wise, the SW groundswell should build to an infrequent 4-6ft by dark Sunday with the S/SW groundswell coming in at a much larger 8ft+ on the sets through the day Monday. Tuesday should hold around the same size as the reinforcing S/SW groundswell fills in, easing back from 6-8ft on Wednesday morning, further into Thursday.

One final trailing front firing up on the tail of the mid-latitude front pushing into WA should produce a final pulse of moderate sized S/SW groundswell for Friday. Sets to 6ft+ are due, easing back through next weekend.

Longer term another moderate sized S/SW groundswell is on the cards for Tuesday the following week, but more on this Tuesday.

Coming back to the winds, and variable breezes are due to develop through tomorrow, remaining so until Wednesday next week, when weak E/SE trades will kick back in, freshening into the following weekend.

16 day Bali Forecast Graph
16 day East Java Forecast Graph
16 day Sumbawa Forecast Graph

Ments: We're nearly through our poor period of NW winds with conditions due to moderate through Saturday with more variable winds from Sunday.

Swell wise, a funky mix of short-range S'ly swell and background S/SW groundswell energy will leave exposed south-east facing spots the go tomorrow and Saturday.

Our new strong SW groundswell for Sunday is still on track with exposed breaks due to reach 5-6ft+ ahead of the larger S/SW groundswell kick Monday, more to 6ft+.

A slow drop in size is due Tuesday, steadying Wednesday to 3-5ft before easing into Thursday.

Later Thursday and more so Friday a new inconsistent SW groundswell is due, generated by a strong mid-latitude front that's currently just south of South Africa.

This system is slightly shadowed by South Africa (right), but inconsistent 4-5ft+ waves should be seen into Friday afternoon before backing off Saturday. We may see winds increase from the NE Thursday before tending more variable into Friday.

Longer term smaller S/SW groundswells are on the cards with fresh NW winds also due to develop again from mid the following week.

16 day Mentawai forecast graph
16 day Nias forecast graph
16 day South Sumatra forecast graph