According to the United States Census Bureau, the city has a total area of 27.3 km² (10.6 mi²). 27.3 km² (10.5 mi²) of it is land and 0.09% is water.
It is bordered by unincorporated Orange County and Los Angeles County to the north and east, La Habra to the west, Fullerton to the southwest, Placentia to the south, and Yorba Linda to the southeast.
Brea, like most of Southern California, enjoys year-round pleasant weather. :
- On average, the warmest month is August.
- The highest recorded temperature was 108°F in 2004.
- On average, the coolest month is January.
- The lowest recorded temperature was 30°F in 2002.
- The maximum average precipitation occurs in February.
The period of April through November is warm to hot and dry with average high temperatures of 73 – 86°F and lows of 51 – 63°F. Due to the moderating effect of the ocean, temperatures are cooler than more inland areas of Los Angeles, where temperatures frequently exceed 90°F (32°C) and occasionally reach 100°F (38°C) in inland areas (due to the moderating effect of the ocean).
The period of November through March is somewhat rainy, as shown in the table to right.
The Los Angeles area is also subject to the phenomenon typical of a microclimate. As such, the temperatures can vary as much as 18°F (10°C) between inland areas and the coast, with a temperature gradient of over one degree per mile (1.6 km) from the coast inland. California has also a weather phenomenon called “June Gloom or May Gray”, which sometimes gives overcast or foggy skies in the morning at the coast, but usually gives sunny skies by noon, during late spring and early summer.
The greater Los Angeles area averages 15 inches (385 mm) of precipitation annually, which mainly occurs during the winter and spring (November thru April) with generally light rain showers, but sometimes as heavy rainfall and thunderstorms. Coastal areas get slightly lower rainfall, while the mountains gets slightly higher rainfall. Snowfall is extremely rare in the city basin, but the mountains within city limits slopes typically receive snowfall every winter.
