Santiaguinos tend to abandon their city every summer during the school holidays that run from the end of December to early March. February is a particularly popular vacation time, when nearly everybody who's anybody is out of town. If you're not averse to the heat, this can be a good time for walking around the city; otherwise spring and fall are better choices, as the weather is more comfortable. Santiago is at its prettiest in spring when gentle breezes sweep in to clean the city's air of winter smog and the lavender-blooming jacaranda, and the yellow-blooming aromo (a type of acacia) come into flower.
Spring and fall are also good times to drive up through the Cajón del Maipo, when the scenery is at its peak. In spring, the plum and cherry trees are in bloom, and in fall, you get some foliage change, and maybe an early snow. Also in fall, the vineyards around the city celebrate the vendimia—the grape harvest—with colorful festivals that are an opportunity to try traditional Chilean cuisine as well as some of the country's renowned wines. Winters in the city aren't especially cold—temperatures rarely dip below freezing—but days are sometimes gray and gloomy, and air pollution is at its worst, making it a good time to head to the beach or mountains.