Weather in Byron Bay in September

Prime time. If you get to pick your dates, September is the one. Highs average 21.5 °C, lows 18.5 °C, and rain falls on 7 days — nothing in the month is working against you.

September ranks 2 of 12 in Byron Bay. Only August scores clearly higher, and the difference is small enough to be settled by price rather than weather.

Rain on 7 days, 1 of them heavy. Enough to need a plan B, not enough to need a plan around it. Nothing specialised needed — this is the month you pack for the trip rather than for the weather.

What the averages hide

Averages flatten a month, and this one hides a few things: it never really gets hot: not one day in an average September reaches 30 °C; the day barely swings — 3 °C between the overnight low and the afternoon high. Across the twenty years measured, the hottest September day reached 27.3 °C and the coldest night fell to 13 °C, and the wettest single day dropped 36 mm — roughly 97% of the month's rain in one day.

September is moderately variable: 4 mm in the driest year against 118 mm in the wettest, around an average of 37 mm. Roughly two Septembers in three land near that average, and the third does something else entirely.

Wind sits around 19.9 km/h — a steady breeze rather than a nuisance, and welcome on the warmer days, and humidity is unremarkable at 72%.

How September sits in the year

Temperatures hold steady either side: 20.1 °C in August, 21.5 here, 22.7 in October. Nothing about the timing within the month matters much.

Daylight in September

11.9 hours of daylight, gaining 0.8 hours across the month. That is between Byron Bay's extremes of 13.9 and 10.3 hours, so days are long enough not to constrain the plan.

Sea temperature

The sea sits at about 21.9 °C in September — comfortable for a proper swim. The sea peaks at 26.5 °C in February and bottoms out at 21.5 °C — water lags the air by a month or two, which is why the best swimming often comes after the best weather.

How busy it gets

Peak season. Expect the highest prices of the year and to be booking well ahead. If the dates are flexible, May is the trade worth considering — 8 points weaker on weather, and materially quieter.

Crowd levels are estimated from climate desirability and school-holiday calendars, not from visitor numbers.

September in Byron Bay versus nearby

If Byron Bay is one option among several, the nearby comparison is worth making. Brisbane is close enough to be a coin toss — 2.7 °C warmer, the same number of rain days. Coffs Harbour is close enough to be a coin toss — within a degree on temperature, the same number of rain days.

So: September is effectively as good as it gets here — 1 points behind August, which is inside the margin where the weather stops being the deciding factor and price starts being it.

Every month in Byron Bay

See all twelve months in Byron Bay, or where else to go in September.