Oaxaca, where it's located

The climate of Oaxaca de Juárez is sub-tropical, with a very mild winter from mid-November to early March, during which it can get cold at night, and a warm, relatively rainy summer from June to October.
Oaxaca is the capital of the state of the same name and is located in southern Mexico, at 1,550 meters (5,000 ft) above sea level, in the tierras templadas. We are south enough to be sheltered from the cold waves from the United States that can affect northern Mexico in winter. However, in winter, sometimes the temperature can drop below 5 °C (41 °F), but even in these cases, during the day it generally remains around 20 °C (68 °F).
On the hottest days of the year, between March and May, the temperature can reach 33/34 °C (91/93 °F). In summer it is not too hot, actually it can get cool at night.
The average temperature of the coldest month (December) is of 18 °C (64 °F), that of the warmest month (May) is of 23.6 °C (74 °F). Here are the average temperatures.
Oaxaca - Average temperatures
Min (°C)101213151717171616141110
Max (°C)262930313028272726272627
Min (°F)505455596363636161575250
Max (°F)798486888682818179817981

Precipitation amounts to 655 millimeters (25.8 inches) per year: so, it is at an intermediate level. It ranges from 5 mm (0.2 in) in the driest months (January, February, December) to 140 mm (5.5 in) in the wettest (June). The rains are not abundant, because the city is located in a valley, and is protected by the mountains. Here is the average precipitation.
Oaxaca - Average precipitation

On average, there are around 2,140 sunshine hours per year. Here are the average sunshine hours per day.
Oaxaca - Sunshine


Best Time

The best time to visit Oaxaca is from November to February, but basically you can also go from March to May, since it is not very hot as in other areas of Mexico.