Weather in Mar del Plata in December

A good month. December works. It is not the peak, but nothing about it fights you. Highs average 22.8 °C, lows 14.7 °C, and rain falls on 11 days — nothing in the month is working against you.

December ranks 2 of 12 in Mar del Plata. Only November scores clearly higher, and the difference is small enough to be settled by price rather than weather.

Rain on 11 days, 4 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

The averages here are honest — no hidden extremes worth planning around. Across the twenty years measured, the hottest December day reached 33.1 °C and the coldest night fell to 7.9 °C, and the wettest single day dropped 149 mm — roughly 130% of the month's rain in one day.

December is moderately variable: 41 mm in the driest year against 257 mm in the wettest, around an average of 115 mm. Roughly two Decembers in three land near that average, and the third does something else entirely.

Wind sits around 16.5 km/h — a steady breeze rather than a nuisance, and welcome on the warmer days, and humidity is unremarkable at 72%.

How December sits in the year

The month is on the way up: 3.3 °C warmer than November, and January adds another 1.7 °C. Late in the month feels noticeably different from the start of it, which is worth knowing if the trip is short.

Daylight in December

December is at or near the longest days of Mar del Plata's year: 14.8 hours of daylight, holding steady all month. Evenings are the real gain — dinner outdoors still happens in full light.

Sea temperature

The sea sits at about 16.6 °C in December — cold — a quick dip rather than a swim, and a wetsuit if you are in for longer. The sea peaks at 19.9 °C in February and bottoms out at 9.7 °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 — 9 points weaker on weather, and materially quieter.

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

December in Mar del Plata versus nearby

If Mar del Plata is one option among several, the nearby comparison is worth making. Buenos Aires is close enough to be a coin toss — 3.2 °C warmer, 3 days less rain. Rosario is the weaker option in December — 8.7 °C warmer, the same number of rain days.

So: December is effectively as good as it gets here — 0 points behind November, which is inside the margin where the weather stops being the deciding factor and price starts being it.

Every month in Mar del Plata

See all twelve months in Mar del Plata, or where else to go in December.