Oyo State covers approximately an area of 28,454 square kilometers and is ranked 14th by size, it is bounded in the south by Ogun State, in the north by Kwara State, in the west it is partly bounded by Ogun State and partly by the Republic of Benin, while in the East by Osun State. The landscape consists of old hard rocks and dome shaped hills, which rise gently from about 500 metres in the southern part and reaching a height of about 1,219 metres above sea level in the northern part. Some principal rivers such as Ogun river, Oba, Oyan, Otin, Ofiki, Sasa, Oni, Erinle and Osun river take their sources from this highland.
Oyo State contains a number of natural features including the Old Oyo National Park. In this location there was earlier habitat for the endangered African Wild Dog, Lycaon pictus; however, this canid is thought to have been locally extirpated at the present.
The Climate is equatorial, notably with dry and wet seasons with relatively high humidity. The dry season lasts from November to March while the wet season starts from April and ends in October. Average daily temperature ranges between 25 °C (77.0 °F) and 35 °C (95.0 °F), almost throughout the year.