Lima's peak tourist season is from June to August, which is the dry season in the highlands, and this is the best time to go if you're interested in hiking. The wettest months are December through April, though travellers visit year-round because it rarely rains for more than a few hours and there's still plenty of sunshine to enjoy.
But Lima has its own climate, it's generally hot during the summer and grey during the winter when the fog (garua) comes in. It's chilly to cold during these months. Lima is situated just 12 degrees below the equator, but its temperatures, modified by the cold Peru (Humboldt) Current, average 21° C in Jan and 15° C in July. It has an arid climate with low precipitation; the average annual precipitation is 26 mm; sea mists and occasional light drizzles and fog during the winter supply moisture.