Understanding climate and its associated factors was familiar to Africans before contact was made with Western-made science. Introducing African learners to formal education seems to bring a disconnect between their indigenous knowledge about their environment and what is taught in the formal school curriculum. The indigenous knowledge systems related to environmental conservation and climate change in Africa are sparingly represented in the official curriculum, which is dominated mainly by the Western science experience. This study identified the Yoruba Indigenous Knowledge System (YIKS) relevant to teaching environmental-related concepts. The Yoruba culture that is prominent in southwestern Nigeria is put into perspective under ethnoreligious practices, knowledge of indigenous food crops, and indigenous knowledge of weather and climate themes. The study relied upon the multi-sourced method to obtain data. The primary data was sourced from community elders, local farmers, experienced extension officers who have worked among the Yoruba, Yoruba language experts and a Yoruba experienced ethnobiologist who was selected through snowballing. The data were content analysed. Among the YIKS on weather and climate is that rains are categorised based on their characteristics and timing. This YIKS is useful when learners are taught weather charts or diaries, and they can refer to the rain category based on the specified characteristic of the rain beyond indicating that there was rain. Based on the findings from this study, recommendations are made on how YIKS related to environmental conservation can be used to reinforce meaningful learning of environmental conservation and climate change to protect the environment.