Hajj takes place over five days in the Islamic month of Dhul Hijjah (the twelfth month of the Islamic lunar calendar), culminating in the Festival of Eid al-Adha. Because the Islamic calendar is lunar, Hajj rotates through the Gregorian calendar over roughly a 33-year cycle. When Hajj falls in the Northern Hemisphere summer (as it will for much of the 2020s and 2030s), temperatures in Mecca regularly exceed 45°C, making the outdoor rituals physically demanding and potentially dangerous for elderly or infirm pilgrims.
Umrah can be performed at any time of year. Outside of Ramadan and the Hajj season, the city is less crowded and the heat, while still intense, is more manageable. Ramadan draws millions of additional worshippers to both Mecca and Medina for prayers and the breaking of the fast.
Mecca's climate is extremely hot and dry year-round. Even outside summer, daytime temperatures rarely fall below 30°C. Pilgrims should drink water constantly and limit outdoor exposure during peak afternoon heat.