Background: An accumulating body of research studies have presented effects of climate change on human health. The current state of climate change supports the notion of elevated incidences of heat waves in future. The understanding of role of increasing temperatures and heat waves on altered mental health conditions stands crucial, in light of wide spectrum of effects warming climate imparts on mental health and well-being status. Methodology: Research studies with findings related to increasing temperatures, mental health and behavioural alterations, and psychopathological outcomes are highlighted in this review. Articles were searched using Google Scholar from the year 2005 to 2018 by entering keywords; increasing temperature and mental health, heat waves and mental health, heat waves and behavioural disorders, climate change and mental health, and, global warming and mental health. Studies were also selected from reference lists of the articles emerging out from these keywords provided. Newspaper articles and reports with details of heat waves in Pakistan are also included. Results: Extreme heat exposure event is found to result in adverse mental, mood and behavioural consequences; including anxiety, aggression, and violence. Heat waves are found to potentiate risk for hospital admission, also due to mental disorders. Heat-associated mental health alterations may be attributed to compromised thermoregulation, pre-existing mental illness, old age, substance abuse and prescription medications effects, and up-regulation in release of stress hormones. Conclusion: Keeping in view the impact of warming climate on mental and behavioural disorders, it appears significantly important to promote research aiming to decipher heat-induced mental health outcomes. In particular, studies are encouraged to be carried out to understand effects of increasing temperatures and heat waves on impaired mental health and psychological well-being state, develop heat-associated mental health mass awareness campaigns, and plan mental health response actions in Pakistan, which currently remain under-represented.