NASA has been studying a region of Texas where four of the world's largest wind farms are located. According to the NASA research, this area has had an increase in land surface temperature over the last nine years that researchers are connecting to local effects of the turbines. These for wind farms are located in West-Central Texas.
According to the NASA research, the wind farms have caused an increase in the surface temperature of .72°C per decade during the study period. Only the surface temperature in the area of the wind farms have increased while the temperature in areas adjacent to the wind farms has not changed. The cause of the surface temperature increase is most likely because of the turbulence caused by turbine wakes says NASA.
The turbulence is believed to act like a fan by pulling down warmer air from higher altitude at night. The warming trend observed by the NASA researchers occurred mostly at night. This particular region of Texas has land surface temperatures after sunset that typically cools faster than the air. It's worth noting that during the day the researchers had expected to see a slight cooling effect. However, in the daytime, the data showed slight warming or no effect on climate.