Mosquitoes in particular are highly sensitive to temperature. The mosquitoes that can carry malaria (Anopheline spp.) generally do not develop or breed below about 16° C, and the variety that transmits dengue fever (Aedes aegypti) is limited by winter temperatures below 10° C.
Warmer global temperatures will allow an expansion of the geographic range within which both the mosquito and parasite could survive with sufficient abundance for sustained transmission. Model predictions indicate that a 3° C global temperature rise by 2100 could increase the number of annual malaria cases by 50-80 million (not considering factors such as local control measures or health services)
Wikipedia's page dedicated to Global Warming... It briefly delves into the history, causes, effects, and some of the potential solutions to this global conundrum.