Mecca (Makkah), Islam's holiest city, lies inland in western Saudi Arabia in the Hejaz region, set in a narrow valley among barren hills about 70 km east of the Red Sea coast and Jeddah, at approximately 21.42°N, 39.83°E. It has a hot desert climate (Köppen BWh) that is among the hottest of any city on Earth, with extremely hot summers and warm winters, its inland valley setting making it even hotter than coastal Jeddah while keeping some coastal humidity.

Summer, from May to September, is exceptionally hot, with June and July the hottest months — average highs around 43–44°C and peaks that regularly exceed 47–49°C, among the highest reliably recorded of any major city. The valley setting traps heat, and while humidity is lower than on the coast, it is high enough at times to make the extreme heat genuinely dangerous. Rain is essentially absent, and the sun is relentless.

Winter, from December to February, is warm and pleasant, with January the coolest month — average highs around 30°C and mild nights near 18–19°C. This is comfortably the most comfortable season, with warm, sunny days and only rarely any genuine chill. The mild winter and the ferocious summer heat are a significant consideration for the millions of pilgrims who visit, since the timing of the Hajj shifts through the seasons each year.

Mecca is very dry, receiving only around 100–130 mm of rain a year, almost all of it falling between November and January; the summer is essentially rainless. The rain that does come can arrive as sudden, torrential downpours, and because the city sits in a valley among hills, these have caused dangerous flash floods that surge through the low-lying centre. Live rainfall, humidity, and pressure readings for the city are shown in the panels above.

Mecca's valley-among-hills setting makes it a heat trap, giving it some of the most extreme summer temperatures of any city and posing a real challenge during the Hajj and Umrah pilgrimages, when vast crowds gather outdoors and authorities take extensive measures against heatstroke. Its most dangerous weather event is the rare but violent flash flood, when a sudden downpour funnels through the surrounding hills into the confined valley.

To follow any single measurement in Mecca more closely, use our live instruments: the online barometer for atmospheric pressure, the thermometer for temperature, the hygrometer for humidity, the anemometer for wind speed, the wind vane for wind direction, and the rain gauge for rainfall.