Sea temperature and swimming season in Arica

The sea off Arica is comfortable for swimming from December to May. It peaks at 21.5°C in February and drops to 16.8°C in August.

"Warm enough" is a judgement, not a fact

There is no objective temperature at which the sea becomes swimmable. A Norwegian and a Spaniard will disagree, and neither is wrong. The season above uses 19.0°C — the bottom of the range most people describe as comfortable in swimwear — but here is what other thresholds imply:

If you are	Minimum	Months you can swim
Hardy	16.0°C	12 of 12
Most people	19.0°C	6 of 12
Prefer it warm	22.0°C	none
Prefer it hot	25.0°C	none

Month by month

Sea temperature, the air you climb out into, and the wind that decides how that feels.

Sea temperature, air temperature, wind and daylight by month.
Month	Sea	Air	Wind	Feels	What to wear
January	20.5°C	25.5°C	2.2 m/s	Comfortable	shorty, or nothing if you are acclimatised
February	21.5°C	26.5°C	2.1 m/s	Comfortable	none, or a rash vest
March	20.7°C	25.3°C	2.3 m/s	Comfortable	shorty, or nothing if you are acclimatised
April	19.7°C	24.5°C	2.1 m/s	Comfortable	shorty, or nothing if you are acclimatised
May	19.1°C	20.6°C	2.2 m/s	Comfortable	shorty, or nothing if you are acclimatised
June	18.1°C	19.0°C	2.2 m/s	Bracing	shorty, or nothing if you are acclimatised
July	16.9°C	17.6°C	2.1 m/s	Bracing	3/2 mm full suit
August	16.8°C	19.2°C	2.1 m/s	Bracing	3/2 mm full suit
September	16.9°C	21.0°C	2.3 m/s	Bracing	3/2 mm full suit
October	17.2°C	21.4°C	2.5 m/s	Bracing	3/2 mm full suit
November	18.1°C	22.5°C	2.7 m/s	Bracing	shorty, or nothing if you are acclimatised
December	19.2°C	23.8°C	0.9 m/s	Comfortable	shorty, or nothing if you are acclimatised

Air is the average daily maximum — roughly what you would meet swimming in the middle of the day. An arrow marks months where the air is colder than the sea.

When in the day can you swim?

Daylight and burn risk by month, in America/Santiago local time.

Month	Sunrise	Sunset	Daylight	Peak UV
January	07:17	20:24	13h 07m	14.8
February	07:34	20:15	12h 41m	14.9
March	07:43	19:56	12h 12m	13.8
April	06:51	18:31	11h 40m	11.3
May	07:00	18:14	11h 15m	8.8
June	07:11	18:12	11h 01m	7.5
July	07:13	18:20	11h 07m	7.9
August	07:01	18:30	11h 29m	9.8
September	07:36	19:36	11h 59m	12.3
October	07:11	19:42	12h 30m	14.0
November	06:56	19:55	12h 59m	14.5
December	06:59	20:13	13h 14m	14.5

Open water burns faster than a beach: the surface reflects sunlight up at you, and sunscreen washes off in the first few minutes. A long swim under a UV index above 6 needs a rash vest more than it needs more cream.

What the bands mean

From	Description	In practice
above 26°C	Bath-like	Warm enough that it offers no cooling at all
above 22°C	Very comfortable	Swimwear, no time limit for most people
above 19°C	Comfortable	Pleasant once you are in; most people swim happily
above 16°C	Bracing	Swimmable but short; many prefer a shorty wetsuit
above 12°C	Cold	Wetsuit territory. Unprotected swims should be brief
below 12°C	Dangerous	Cold shock risk. Specialist gear and supervision

Do you need a wetsuit in Arica?

Some months, yes. The sea drops to 16.8°C in August. What thickness, month by month, for swimming and for surfing →

Other coastal cities in Chile

Where these numbers come from, and what they miss

Open water, not your beach. The measurement is a satellite cell about 28 km across, centred 13.7 km from Arica. Shallow bays and lagoons run warmer; exposed coasts with upwelling run colder, sometimes by several degrees.
Surface temperature. Below a few metres the sea is often noticeably colder, and in summer a warm surface layer can sit over much colder water.
A six-year average, not a thirty-year normal. Sea temperature varies little between years, so this is close — but it is not a climate normal, and any individual year will differ.
Averages hide storms. A monthly mean says nothing about the week a cold current arrives.

Full methodology, sources and known limitations