This study focused on the variability of temperature across the Oklahoma City metropolitan area (OKC) during a six-week period in early 2007. Twenty portable temperature and humidity sensors were strategically placed at various fire stations throughout Oklahoma City from 20 February through 1 April 2007. Data from these sensors and two local Oklahoma Mesonet sites were used to evaluate the spatial differences in temperature for the area. An intercomparison was also performed prior to the deployment in Oklahoma City using the portable sensors and the Norman (NRMN) Mesonet site during 30 January through 10 February 2007 at Max Westheimer Airport in Norman, OK. A post deployment calibration was performed in September 2007 at the Oklahoma Climatological Survey calibration laboratory. The primary goal of this project was to evaluate the temperature variability across OKC and to verify the existence and intensity of a nocturnal urban heat island and possible daytime urban cool island in OKC. It was discovered that an urban heat island and cool island exist in OKC. The urban heat island was generally strongest just before sunrise yielding an average temperature difference between the central business district (CBD) and the nearby rural areas of approximately 2°C; a temperature difference as great as 7°C was also recorded during the study period. The urban cool island typically occurred around midday and was much weaker than the urban heat island. The average temperature difference between the CBD and the surrounding suburban areas was less than 1°C. However, the surrounding rural areas were typically still cooler than the CBD during the urban cool island.