Mazatlan has a permanently sunny forecast.  The average year-round temperature hovers right around 78 degrees, or about 26 degrees Celsius. The hottest months tend to be June through October with average temperatures climbing into the 80s or 90s (the high 20s-low 30s Celsius). There are occasional afternoon showers during its "rainy season" from May to mid-October. The weather tends to be a little humid because of the ocean, especially during the summer months. To see what the weather currently is in Mazatlan, go here:The weather in Mazatlan

Puerto Vallarta, on the other hand, has a more tropical climate than Mazatlan, and more of a rainy season. The town’s weather is often compared to that of Hawaii, because they share the same latitude. Temperatures generally stay between a balmy 77 degrees Fahrenheit and a slightly balmier 90 degrees (25-32 degrees Celsius), all year round. The rainy season begins in May/ June, and lasts until about mid-October. During this time, Puerto Vallarta receives sometimes torrential downpours that help it regain the green of its lush, tropical vegetation. Because of the protection afforded it by the second-largest bay in all of the Americas, Banderas Bay, Puerto Vallarta is rarely affected by hurricanes or tropical storms. For current Puerto Vallarta weather, check out this site: The weather in Puerto Vallarta