ABSTRACTMany scientists have reported that global warming have significant impact on phytoplankton community, however, the impact of global warming on phytoplankton communities in suburban made lake is less understood. Therefor the objective of this study are to observe the effect of variable weather conditions on the diversity and succession of phytoplankton in mesotrophic lake (Seri Serdang) and oligotrophic lake (Engineering Faculty Lake). Samples were collected from surface water and species diversity (Shannon Weaver Diversity Index) was calculated. Daily weather and rain fall were recorded. A total of 65 species from five divisions (Chlorophyta, Euglenophyta, Cyanophyta, Bacillariophyta and Dinophyta) and 52 species belonging to six divisions (Chlorophyta, Cyanophyta, Bacillariophyta, Euglenophyta, Cryptophyta & Charophyta) were recorded from Engineering Faculty Lake and Seri Serdang Lake respectively. Division of Chlorophyta was found most dominant in both lakes during all the weeks (67%). The most dominant species in Faculty Engineering Lake was Microcystis aeruginosa during all weather conditions. Whereas, the most dominant species in Seri Serdang Lake during all weather conditions were Chlamydomonas reinhardtii, Planktothrix agardhii. The phytoplankton density was low during dry weather conditions for both lakes. The present finding suggested noticeable correlation between weather changes to the alteration of population density of phytoplankton.