June to August is the rainy season, which means it quite often rains at night, but is usually sunny and pleasant during the day. The rain helps to moderate the warmth, but you should have an umbrella with you during this season. There are several customs in Mexico that may be new to you. For example, it is customary to shake hands when being introduced, and women often kiss each other's cheeks when meeting and leaving. Mexicans do not always remove their shoes while inside their homes.
Smoking is largely acceptable, but becoming more unpopular.
Unlike some places in the world, the legal system in Mexico has some flaws. Policemen are not always looking after your best interests, and it is always advisable to stay strictly within the law. When in a car, the driver and passengers must always wear seat belts. It is illegal to drive after drinking alcoholic beverages. Record the numbers of your credit cards, passport, etc.