Don't listen to anyone, even me. ;-)
People's internal thermostats vary greatly. I've seen claims of "perfect weather" for places where daytime highs rarely reach the 80s. My area is one in which most foreigners bail out for summer because they think it's intolerable because everybody else bails out for summer. The majority of them have never actually spent a summer here. I don't know Merida, but my advice would be to try it before committing to anything. Have an emergency escape fund in case you find you really can't stand the weather, especially for the first couple of years. But if you like the place, give it a chance.