PUERTO PENASCO · SEA OF CORTEZ · AUGUST
Puerto Penasco in August means bathwater in the Sea of Cortez. The sea averages 89.5°F, the first swim of the morning feels like stepping into a warm bath, and the air matches it at 92.7°F on an average afternoon. Rain barely interrupts any of it.
Most U.S. visitors still arrive by car through the Lukeville-Sonoyta border crossing. Mar de Cortes International Airport went more than five years without scheduled commercial flights, and a new scheduled route resumed service in mid-2026, so flying in is possible again.
THE MONTH AT A GLANCE · PUERTO PENASCO
August in Puerto Penasco brings 89.5°F water, 92.7°F afternoons and almost no rain, so swim early and late and give the middle of the day to shade.
AUGUST NORMALS 1991-2020 · SEA 89.5°F · RAIN 0.5 DAYS · 13 HOURS 19 MINUTES OF DAYLIGHT
Go for: warm-water swimming at Sandy Beach and Cholla Bay, long light at both ends of the day, and a month with very few rain days.
Think twice before: counting on cool nights, since the low averages 84.2°F, or booking without reading the State Department’s Level 3 advisory for Sonora.
Air and rain: Open-Meteo / ECMWF ERA5 reanalysis (a model grid cell, not a station) · Sea: Open-Meteo Marine API · Daylight: sunrise-sunset.org · full sources at the end
On this page
- Puerto Penasco weather in AugustHighs of 92.7°F, lows of 84.2°F and half a rain day
- Can you swim in Puerto Penasco in August?Sea at 89.5°F, and why it reads a shade warm
- How busy and how expensive is August?The 3% Sonora lodging tax and the price data we could not find
- Things to do in Puerto Penasco in AugustSandy Beach, Cholla Bay and the biosphere reserve edge
- Puerto Penasco itinerary for AugustTwo days built around the 5:59 a.m. sunrise
- Puerto Penasco in July, August or SeptemberHighs, lows, rain and sea temperature for all three months
- Is August a good time to visit Puerto Penasco?Who it suits, who should pick September, and the Level 3 advisory
The U.S. State Department’s Mexico Travel Advisory, reissued in May 2026, lists the State of Sonora at Level 3, reconsider travel, due to terrorism and crime. Read the Sonora entry before booking anything for August or any other month.
Puerto Penasco weather in August
| Measure | August normal, 1991-2020 |
|---|---|
| Average high | 92.7°F |
| Average low | 84.2°F |
| Precipitation | 0.29 inches |
| Days with 0.10 inch or more | 0.5 |
| Days with an inch or more | 0.0 |
| Daylight on August 15 | 13 hours 19 minutes |
Every figure here for air and rain is a 1991-2020 normal from the ECMWF ERA5 reanalysis, served by Open-Meteo for a model grid cell over Puerto Penasco. It is a computed model, not a thermometer reading, because none of the town’s three CONAGUA stations publishes a normals product. August comes out at an average high of 92.7°F, an average low of 84.2°F and 0.29 inches of precipitation. A grid cell on this stretch of the Sea of Cortez may soften the desert coast’s sharp day-night swing, so the real gap between afternoon and night may be wider.
Rain barely registers. An average August records 0.5 days with at least 0.10 inch of precipitation and 0.0 days with an inch or more. That is half a day of measurable rain across the whole month, so the umbrella can stay home and the plans can follow the sun.
The afternoon high and the night low sit 8.5 degrees apart, a narrow gap, and the night gives back almost nothing. Pack for heat around the clock: light cotton, a hat, sandals that can get wet. Since a model cell may understate the swing, one thin shirt for the ride home after dark costs nothing.
On August 15 the day lasts 13 hours 19 minutes. The sun rises at 5:59 a.m. and sets at 7:17 p.m., converted to America/Hermosillo time from 12:59 and 02:17 UTC. The morning swim window opens with that sunrise, when the air is closest to the night low, and the last direct light is gone at 7:17 p.m.
Can you swim in Puerto Penasco in August? Sea temperature
The sea off Puerto Penasco averages 89.5°F in August, per the Open-Meteo Marine API for 2015-2024. That figure is a mean of daily maxima, so it runs a shade warmer than a 24-hour average would. Tables built on 24-hour means will read a little lower for the same water.
In practice this is bathwater. It sits only 3.2 degrees below the 92.7°F afternoon high, so a midday dip brings little relief. Early morning and evening are the better times to swim at Sandy Beach (Playa Mirador) or Cholla Bay, both on the Sea of Cortez.
We found no wind or swell figures for August, so we cannot say how calm the water runs. Ask locally on the day before a long swim.
How busy is Puerto Penasco in August? Crowds and prices
We found no occupancy series and no monthly room-rate data for Puerto Penasco, so we place August on no price scale and crown no month expensive or cheap. The weather data show a plateau: July and September both post 91.1°F highs, and August tops each by 1.6 degrees.
We also have no booking lead-time data, so we give no number of weeks. Reserve the room before any flight. The airport’s scheduled service only resumed in mid-2026 after more than five years, and the drive through Lukeville-Sonoyta remains the default for most U.S. visitors.
Lodging carries a state tax. Sonora’s lodging tax is 3% of revenue under Article 122 of the state’s Ley de Hacienda, in the text published in December 2025. We could not verify how individual hotels display it, so check whether a quoted nightly rate already includes it.
If one line deserves a bigger budget, make it the room’s cooling. Nights only fall to 84.2°F, so a room that cannot cool leaves no recovery hours. We have no rate data on what cooling adds to a nightly price, so compare quotes yourself.
Things to do in Puerto Penasco in August
Swimming carries the month. The sea reads 89.5°F, and daylight on August 15 lasts 13 hours 19 minutes, long enough for an early swim, a shaded gap and a late swim.
Two beaches anchor the water: Sandy Beach (Playa Mirador) and Cholla Bay, both on the Sea of Cortez. We could not verify hours, fees or parking at either, so we give none. The town also sits at the edge of the Alto Golfo de California y Delta del Rio Colorado Biosphere Reserve, a federal protected area decreed on June 10, 1993. It is the critical refuge of the vaquita marina, the world’s most endangered marine mammal, and of the totoaba fish.
The water shifts with the calendar: 87.4°F in July, 89.5°F in August and 88.3°F in September (Open-Meteo Marine API, 2015-2024 daily maxima). The beaches stay the same, so the season shows up mainly in how warm the water feels on the way in.
We found no verified admission data for either beach or for the reserve edge, so we cannot say what is free. Ask locally before you pay for entry anywhere.
Puerto Penasco itinerary for August
Day one. Be at Sandy Beach (Playa Mirador) around the 5:59 a.m. sunrise and swim in 89.5°F water while the air is near the 84.2°F night low. Spend the afternoon in shade, when the high reaches 92.7°F, then return to the water for the last light before the 7:17 p.m. sunset.
Day two. Repeat the rhythm at Cholla Bay: early water, a shaded middle, a late swim. If the weather turns, it should be brief, with 0.5 days of measurable rain in an average August. Move the beach block to the other end of the day and keep going.
Puerto Penasco in August vs July and September
| Measure | July | August | September |
|---|---|---|---|
| Average high | 91.1°F | 92.7°F | 91.1°F |
| Average low | 82.7°F | 84.2°F | 80.6°F |
| Precipitation | 0.09 inches | 0.29 inches | 0.30 inches |
| Days with 0.10 inch or more | 0.2 | 0.5 | 0.8 |
| Sea surface (marine API, 2015-2024) | 87.4°F | 89.5°F | 88.3°F |
August tops July by 1.6 degrees on the afternoon high and 1.5 degrees on the night low, and its sea runs 2.1 degrees warmer. September drops back to a 91.1°F high, but its night low falls to 80.6°F, 3.6 degrees under August, and the water cools 1.2 degrees to 88.3°F. Rain stays scant in all three, from 0.09 inches in July to 0.30 in September.
Shifting four weeks later trades 1.2 degrees of sea warmth for 3.6 degrees of relief at night, at the cost of 0.8 rain days against 0.5. Shifting four weeks earlier cools the afternoon by 1.6 degrees and the sea by 2.1 degrees, with just 0.2 rain days. We cannot say whether either move saves money, because we found no monthly rate data. Our where-to-go-by-month guides cover other months and other places.
Is August a good time to visit Puerto Penasco?
Yes for anyone who wants warm water and long light more than cool nights: 89.5°F sea, 92.7°F highs, half a day of rain. No for anyone who sleeps badly in heat, since the low averages 84.2°F. Either way, the Level 3 advisory for Sonora comes before the flights, and our Travel 101 section is the place to start general trip preparation.
If the answer is no, take September. Its night low is 3.6 degrees cooler at 80.6°F and its sea still reads 88.3°F, and the trade is 0.8 rain days against 0.5. July also cools the afternoon to 91.1°F, the same high as September, but its water is 87.4°F.
Among July, August and September, August has the warmest sea at 89.5°F and the hottest afternoons at 92.7°F.
The last word
Set the alarm for the 5:59 a.m. sunrise and walk into the sea at Sandy Beach: the water reads 89.5°F, the air is still near the night’s 84.2°F low, and 13 hours 19 minutes of daylight lie ahead. Give the afternoon to shade and a cold drink, then swim again before the 7:17 p.m. sunset. If the warm nights bother you, September’s run 3.6 degrees cooler, and our destinations index has other places for other months.
Sources & data for this guide
- Air and rain normals, 1991-2020 · Open-Meteo / ECMWF ERA5 reanalysis, computed for a grid cell over Puerto Penasco · a model reanalysis, not a station record · checked September 2026
- Town weather stations · none of the three CONAGUA stations (Smn, Dge, Obs) publishes a normals product · checked September 2026
- Sea surface temperature · Open-Meteo Marine API, mean of daily maxima, 2015-2024 · checked September 2026
- Sunrise, sunset and daylight, August 15 · sunrise-sunset.org, converted to America/Hermosillo · checked September 2026
- Biosphere reserve · CONANP decree text · conanp.gob.mx · checked September 2026
- Airport service · local press (Codigo Rojo Cajeme, Ahora Noticias Penasco) · checked September 2026
- Lodging tax · Congreso del Estado de Sonora, Ley 9, De Hacienda del Estado de Sonora, text published December 2025 · checked September 2026
- Travel advisory · U.S. Department of State, Mexico Travel Advisory reissued May 2026, State of Sonora · checked September 2026
- We found no occupancy series, room rates, booking lead times, wind or swell data, or beach hours and fees, so none appear. Beach names are common knowledge · check operators when you book.