Santa Fe's weather is difficult to predict. When it is important, I find it helpful to check multiple websites. These tend to be fairly accurate.
National Oceanic and Atmospheric Administration's weather forcast for Santa Fe, NM. Data collected at the Santa Fe Municipal Airport. NOAA weather for Santa Fe, NM
With Weather Underground you can specify which part of town. I have heard that this site is the most accurate for the mountains, where patterns change frequently. Weather Underground for Santa Fe, NM