By Santa Cruz Profunda, from Puerto San Julián · Updated 2026-10-15
If you're planning a trip to Puerto Deseado, the weather isn't a minor detail: almost everything worth doing happens on a boat. Penguin Island is in open sea, and the Deseado estuary has its own tides and wind. This guide brings together what the National Weather Service (SMN, Puerto Deseado Aero station) and National Parks publish, so you know when to go and what to pack, without made-up averages.
The climate in SMN figures
According to the SMN's Climatological Normals 1991–2020 for the Puerto Deseado Aero station (latitude 47.73° S, 81 m elevation), the mean annual temperature is 10.2 °C. The mean annual maximum is 15.9 °C and the mean annual minimum 5.4 °C. Mean annual relative humidity is 64.1%.
Monthly mean temperatures (°C), same source:
- Summer: December 15.1 · January 16.4 · February 15.6
- Autumn: March 13.8 · April 10.5 · May 7.2
- Winter: June 4.3 · July 3.5 · August 5.2
- Spring: September 7.3 · October 10.3 · November 13.1
Mean highs range from about 23 °C in January to about 8 °C in June–July; mean lows from about 10 °C in midsummer to close to 0 °C in July. Over the same normal period, the SMN records on average about 49 days of frost a year (peaking in July) and about 5 days of snow. For precipitation and wind speed, that publication shows N/A (no data) for this station: there's no official average we can cite here. For the day-to-day forecast, check before you travel at Servicio Meteorológico Nacional – Pronóstico.
Wind: the factor that decides whether trips go ahead
Although the SMN doesn't publish an average wind speed for this station in that report, National Parks is clear: westerly winds prevail and blow almost all year round. Tourist activities in Isla Pingüino Interjurisdictional Marine Park are always subject to the weather because the island is in open sea. In practice, that means a trip can be canceled on the day even under clear skies. If you're coming just for the boat trip, leave a spare day.
What it means for the Deseado estuary
The Ría Deseado Provincial Reserve borders the town and can be explored all year round; SiFAP nonetheless recommends the October to April season and advises that, given the area's unpredictable weather and water conditions, it's best to stay at least three days. Here you can see Commerson's dolphins, cormorants (including the red-legged cormorant), sea lions and Magellanic penguins. Sailing on the estuary is usually more “sheltered” than in open sea, but it still depends on wind and tide. Detailed plans: Things to do in Puerto Deseado.
What it means for Penguin Island
National Parks states that trips to the park run only from mid-October to April, for weather reasons, and that this window coincides with the greatest concentration of wildlife (breeding and feeding). The star is the rockhopper penguin, in the only colony of the species on the mainland open to tourists. There are also Magellanic penguins, sea lions and elephant seals. Access: by boat from Puerto Deseado only. Confirm operators, schedules and bad-weather policy with the Tourism Office or check before you travel at Parques Nacionales – Isla Pingüino, panorámica.
When to go, depending on what you're after
- Mid-October to April: the official window for Penguin Island and the season SiFAP recommends for the estuary. Time your trip for this season if marine wildlife is the main reason for going.
- December to February: the SMN's mildest months (averages of 15–16 °C) and the longest days. It's also the busiest time, and summer wind is still a factor: National Parks points out that nights are often cool even in summer.
- October–November and March–April: a good option if you want the wildlife season with less midday heat. October opens the boat season to the island; April closes it. Confirm exact dates with your operator.
- May to September: it's cold (July averages around 3.5 °C), there are more frosts and boat trips to Penguin Island don't run, according to National Parks. The town and some land-based tours carry on, but it's not the time to plan your trip around marine excursions.
The practical summary: if your priority is the estuary + Penguin Island, aim for November–March and book at least three nights. If you can only go in winter, lower your expectations for boat trips and prioritize museums, the waterfront and the lookouts.
What to pack (the kit National Parks recommends)
On the park's overview page, the agency recommends dressing in layers, “onion-style”, because the winds are cold and nights are cool even in summer. A raincoat and windbreaker are the Patagonia visitor's “best friend”. Add comfortable shoes, a hat, gloves, a water bottle and, if you're into birds, binoculars and a field guide. We'd add sunscreen and lip balm: sun and wind dry you out even when it isn't hot.
- Layers: T-shirt + sweater + windproof/waterproof jacket
- A hat that won't blow away and light gloves
- Closed shoes with good soles (the island is rocky)
- Binoculars and a case for your phone or camera
- Seasickness medication if the sea usually gets to you
How to plan your days around the weather
- On the day you arrive, check the SMN forecast and talk to your Penguin Island trip operator: if the sea is rough, reschedule before filling your agenda.
- Do the estuary in a “safer” window of the day (many trips are half-day) and save Penguin Island for the day with the best sea conditions.
- Keep a flexible day for Cabo Blanco, Darwin's lookouts or the museums in case the boat trip is canceled.
To get there along the coast, see The coast along Route 3. The destination overview is at Puerto Deseado.
Before you travel
SMN averages describe a long period (1991–2020); any given day can be much windier or colder. Confirm the forecast by checking before you travel at Servicio Meteorológico Nacional – Pronóstico, the status of trips with your operator and, if you're going to Penguin Island, the latest information from National Parks. The Puerto Deseado Tourism Office (San Martín 1137) can also advise on licensed operators: check before you travel at Turismo Santa Cruz – Puerto Deseado.
Frequently asked questions
What's the best time to visit Puerto Deseado?
If you want to sail the estuary and visit Penguin Island, between mid-October and April, the season National Parks publishes for trips to the park. December to February are the mildest months according to the SMN.
Is it very cold in summer?
In January the SMN average is 16.4 °C, with average highs around 23 °C, but National Parks warns of cold winds and cool nights: bring layers and a windbreaker.
Can you go to Penguin Island in winter?
According to National Parks, trips run from mid-October to April because of the weather. Outside that window, don't count on that trip.
Why are trips canceled even on sunny days?
Because the island is in open sea and the westerly wind can make sailing impossible even when it isn't raining. National Parks states that activities are subject to weather conditions.
How many days should I stay?
SiFAP recommends at least three days in the Deseado estuary area because of the unpredictable weather. That gives you a margin if a trip is canceled.
