Weather in Antofagasta in September

Prime time. September is about as good as Antofagasta gets. Highs average 16.2 °C, lows 12.1 °C, and rain falls on 0 days — nothing in the month is working against you.

Antofagasta barely has seasons. September scores 88 out of 100 against a best of 100 in January — a gap small enough that the month you choose matters far less here than the week you choose. Worth keeping in perspective: September is the weakest month of Antofagasta's year and it is still a perfectly good one. The downside here is small.

Rain is not a factor worth planning around this month. Pack for 16.2 °C days and 12.1 °C nights; the spread matters more here than any single number.

What the averages hide

Averages flatten a month, and this one hides a few things: the day barely swings — 4.1 °C between the overnight low and the afternoon high. Across the twenty years measured, the hottest September day reached 23.5 °C and the coldest night fell to 9.5 °C.

September is dependably dry, and that reliability is the point: across the twenty years measured, the wettest September on record still only managed 1 mm, and the driest managed 0 mm. There is no meaningful variability to plan around, which makes this one of the few months anywhere that you can build a fixed outdoor itinerary against without a fallback. The wettest single day in twenty years of Septembers brought 1 mm. Rain simply is not the variable that decides this trip — heat, crowds and cost are.

Wind is light at 10 km/h, so the temperature on the page is close to the temperature on your skin, and humidity runs at 81%, high enough to notice on the warm days without dominating them.

How September sits in the year

Temperatures hold steady either side: 16 °C in August, 16.2 here, 17.1 in October. Nothing about the timing within the month matters much.

Daylight in September

11.9 hours of daylight, gaining 0.7 hours across the month. That is between Antofagasta's extremes of 13.6 and 10.7 hours, so days are long enough not to constrain the plan.

Sea temperature

The sea sits at about 15.4 °C in September — cold — a quick dip rather than a swim, and a wetsuit if you are in for longer. The sea peaks at 22.4 °C in February and bottoms out at 15.3 °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

Off season. The genuine off season: cheapest by a distance, with the caveat that some tours and restaurants close entirely.

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

September in Antofagasta versus nearby

If Antofagasta is one option among several, the nearby comparison is worth making. Salta is close enough to be a coin toss — 12.9 °C warmer, 1 day more rain. Arica is the weaker option in September — 16.9 °C warmer, the same number of rain days.

So: September works, with January the better month by 12 points if the dates can move. If they cannot, nothing here should stop you booking.

Every month in Antofagasta

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