<p>The study, massive destruction of tropical rainforest and its soaring effect of environmental temperature in southwest Nigeria is currently a big problem facing man, and that if not quickly nip on the bud will get out of hand. The research work based its study area in Southwest rain forest, the sites are: Oluwa, Shasha and Omo-forest reserves. Series of data were collected, data on forest was collected using GIS multi-temporal Landsat imageries to generate current vegetation status and land-use and cover change. Data on temperature was collected from NIMET Abuja, five based years of the following weather stations: Ile Ife; Ondo town; Ijebu ode; Ibadan; and Abeokuta. Results revealed the inverse direction of deforestation and the environmental temperature in the settlements where these forest reserves are found in the south west of Nigeria. Recommendations therefore are: the governments of south west region as well as the federal government should not renege on international policy of tree planting and the adequate security on forest reserves. Aside adequate monitoring of the trees and forests there should be provision for prosecuting contraveners of protection on forest.</p>