Does windy weather cool down the temperature during a sunny day?

What are causes of significant day-to-day temperature changes in the weather within a region?

• For instance, in San Francisco, we often have back-to-back days where two otherwise similarly sunny days will have a daytime temperature difference of ~10º Fahrenheit or more.

• Answer:

  This would generally be due to different air masses sources. For example on day 1, there might be a westerly wind which brings in air that was over the Ocean. Water temperatures off San Francisco are generally in the 50's so the marine air mass is generally pretty cool. This might keep the temperatures in the 60's. On day 2, the wind could shift to the southeast and bring in warmer temperatures from inland area boosting temperatures in to the 70's. Does this answer make sense to you? In fact the different wind directions and distance to the ocean in the SFO area frequently result in a wide range of current temperatures, as much as 10 or even 20 degrees over a short distance. If you're interested you can take a look at local weather stations such as http://www.wunderground.com/US/CA/San_Francisco.html to see the difference.