Backdoor 4 Surf Forecast and Surf Report

Alright, Rusty here. Let’s talk about what’s cooking at Backdoor 4 (United States).

Right now, we’ve got a bit of a slow start, but don’t walk away. The first real sniff of action comes Friday morning, September 4th. It’s early, but the conditions are set up nicely—glassed-off, a light southerly breeze, and a solid 5ft southeast swell pushing in with good energy (539). The water’s sitting at 66°, which is pretty much normal for this time of year, so no surprises there. That Friday morning window is the one to jump on before the wind swings around.

The weekend is a write-off, plain and simple. Strong onshore winds and drop in swell size mean it’s not worth paddling out. Sunday has a brief moment of clean conditions but with tiny waves, so it’s barely a ripple.

Monday morning, September 7th, is a real highlight. Glassy conditions again, a clean 5ft southerly swell, and the energy is building nicely (321). The wind is offshore from the WSW, making for some clean, lined-up waves. This is a standout session for intermediate surfers—the size is manageable, and the quality is there.

Tuesday, September 8th, gets bigger. The morning swell jumps to 8ft, and by the afternoon it’s 8ft from the SSE. The energy is cranking (1033 and 1486), and the wind is clean offshore, but this is now pushing into expert territory. That’s a heavy paddle, and the reef won’t forgive mistakes. If you’re not experienced, stay out of the water.

The middle of the week sees solid, clean swell holding through Wednesday and Thursday, but the size stays big—8ft to 10ft, with offshore winds at times. This is all expert-level stuff. The energy readings are massive (up to 3166), so expect powerful, barreling waves. Not for the faint-hearted.

Friday, September 11th, is a real standout for the experienced crew. The morning is a bit muscular at 8ft, but the afternoon drops to a more manageable 7ft, with clean offshore winds and a long 11-second period. That’s groundswell energy, and it is going to line up beautifully on the reef. The energy is still high (1542), so the waves will have push. This is the best session of the whole run for those who can handle it.

After that, the swell eases into the weekend of September 12th–13th. Saturday morning offers 6ft with clean conditions, which is a nice return to intermediate-friendly surf. The period is long at 12 seconds, so the waves will have shape and power but not the heavy size.

Then we hit a dry spell. From Sunday afternoon through to Wednesday, September 16th, the surf drops off hard. Tiny waves, onshore winds, and choppy conditions make it a waste of time.

There’s a late pulse kicking up around Thursday, September 17th, but it’s too big again (8ft) and messy. Friday, September 18th, sees the biggest swell of the forecast—12ft from the south with a very long 14–15 second period. The energy is through the roof (4651–5454). That’s a massive, powerful groundswell, and with offshore winds, it’s an epic day for experts only. This is a promising, standout event but it’s far out, so keep an eye on it.

The final weekend, September 19th, still holds size at 8–8ft, but the wind is cross-shore, so it’s not as clean.

Best bets: Glassy Friday morning September 4th for a fun start, Monday September 7th for clean intermediate waves, and Friday September 11th afternoon for the best expert session. The big pulse on September 18th is worth watching.

Rusty.

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