4. Puerto Vallarta, Mexico.
Puerto Vallarta is a lovely resort town on the Pacific coast of Mexico. With an average high of 80 degrees Fahrenheit (26 degrees Celsius) and an average low of 62 degrees Fahrenheit (16 degrees Celsius), the weather is dry and mild in January. While winter is considered peak season, you may still encounter lighter crowds than at popular Caribbean spots this time of the year. Known for its beaches, Puerto Vallarta’s section of Bahía de Banderas doesn’t disappoint.