You’re planning a trip to the southwest corner of the island. Everyone tells you Puerto Rico is just "tropical," but that's a massive oversimplification. If you're heading to the salt flats or the red cliffs of Los Morrillos, the cabo rojo puerto rico weather is a different beast entirely compared to the rainforests of El Yunque or the humid bustle of San Juan.
It’s dry. Sorta desert-like in spots.
Cabo Rojo sits in a rain shadow. While the north coast gets hammered by trade winds and frequent showers, the southwest is significantly more arid. You'll see cacti growing next to the beach here. That's not a mistake of nature; it's the result of the Cordillera Central mountain range squeezing the moisture out of the clouds before they ever reach the coast.
The Reality of the Dry Season
If you want the "perfect" window, most people point to December through April. Honestly, they’re right. This is the sweet spot where the humidity drops—at least as much as it can in the Caribbean—and the trade winds keep things from feeling like a literal oven.
During these months, daytime highs usually hover around 84°F or 85°F. At night, it actually gets "chilly" by local standards. You might see the mercury dip to 68°F in February. It sounds warm, but with the ocean breeze, you'll actually see locals wearing light sweaters. Don't laugh until you’ve been there.
Rain is almost non-existent in February and March. If it does rain, it’s a ten-minute "liquid sun" event that’s over before you can find your umbrella.
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When the Heat Hits: May to October
Things change in May. The humidity starts to climb, and the "early rainy season" kicks in. But here’s the thing about cabo rojo puerto rico weather in the summer: even when it’s "wet," it’s still drier than the rest of the island.
September is technically the wettest month. On average, you're looking at about 11 inches of rain, but it’s not a constant drizzle. It’s usually a massive afternoon thunderstorm that clears the air. Then the sun comes back out, and it’s steamier than a sauna.
The Hurricane Factor
You can't talk about Cabo Rojo in the fall without mentioning hurricane season. It runs from June 1 to November 30. Peak activity is usually mid-August through September.
Should you avoid it? Not necessarily.
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Prices for rentals in Boquerón or Joyuda crater during this time. You can get incredible deals. Just realize that if a system moves in, your trip is basically over. Most modern hotels have massive generators and cisterns, but the local vibe gets very serious very quickly when a storm is brewing in the Atlantic.
Water Temperatures and Beach Safety
The water in Cabo Rojo is almost always like bathwater. We're talking 78°F in the winter and up to 84°F or 85°F in August and September.
Because Cabo Rojo is on the west/southwest coast, the beaches like Playa Sucia (La Playuela) and Boquerón are generally much calmer than the Atlantic-facing beaches in the north. However, the heat index here can be brutal. Because it’s so dry and breezy, you might not feel yourself sweating as much as you do in San Juan.
That’s how people get heatstroke.
Drink double the water you think you need. The sun at the Cabo Rojo Lighthouse is intense—there is zero shade on those cliffs.
Monthly Breakdown of What to Expect
Let's get specific about the numbers because "warm" means different things to different people.
In January, it's the peak of "cool" weather. Highs stay near 84°F, and the chance of a wet day is only about 12%. It’s the clearest time of year. If you want to see the pink salt flats at their most vibrant, the bright sun and lack of rain make the colors pop.
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By May, the clouds start moving in more frequently. You’ll have overcast skies about 50% of the time. This is actually a relief if you're hiking the wildlife refuge because it keeps the direct sun off your back.
August is the furnace. It’s the hottest month, with an average high of 90°F. But it’s the "feels like" temperature—the heat index—that will get you. It easily hits 100°F with the humidity.
Actionable Tips for Navigating the Weather
If you’re heading down there soon, here is how you actually handle the climate:
- Book for February if you hate rain. It’s the driest month by far. You have a 90% chance of a perfectly sunny day.
- Hike the Lighthouse before 10:00 AM. Seriously. After that, the limestone cliffs radiate heat like a stovetop. There is no recovery once you’re out there.
- Watch the "Vaguadas." Even outside of hurricane season, Puerto Rico gets these low-pressure troughs called vaguadas. They can dump three days of rain out of nowhere. Check the NWS San Juan office (not just your phone’s default weather app) for the most accurate local alerts.
- Check the tide and wind for Playa Sucia. If the wind is kicking up from the south, that calm turquoise water can get choppy and bring in seaweed.
The southwest coast is a different world. It’s rugged, it’s hot, and it’s remarkably consistent. Just don’t forget the high-SPF sunscreen; the Cabo Rojo sun doesn't play around.
For your next move, check the local National Weather Service (NWS) San Juan "Point Forecast" specifically for Cabo Rojo rather than a general Puerto Rico search, as the microclimate here often defies the island-wide average.