At 2300 meters above sea level, Mexico City experiences a more moderate climate than much of the rest of the country.  In fact, frost is not uncommon in the city as temperatures can get cold in the winter months.  Both December and January see average afternoon highs of approximately 20 degrees and average overnight lows of 6 degrees Celsius.  The warmest months are April and May with afternoon highs near 27 degrees.  Overall the city receives 816 millimeters of precipitation a year.  Much of that rainfall is concentrated in the summer months.  The wettest month is July with 175 millimeters of rain on average.  February is the driest month with 4 millimeters of rain.