There a number of websites who provide fairly accurate weather reports and forecasts for multiple cities in Mexico. You can alphabetically look up the city you are traveling to with these websites:
Wunderground.com Mexico weather section
Before driving to Mexico, make sure to check the Mexican weather forecasts for your destination.
The Mexican roads and highways can be heavily influenced by weather conditions. In areas like Baja, heavy rain often washes out parts of the roads and highways. For this reason, we strongly encourage you to review weather forecasts before your Mexican road trip. You should also review our Mexico driving safety page.