Climatology
This page presents Micronesia, Fed. Sts.'s climate context for the current climatology, 1991-2020, derived from observed, historical data. Information should be used to build a strong understanding of current climate conditions in order to appreciate future climate scenarios and projected change. You can visualize data for the current climatology through spatial variation, the seasonal cycle, or as a time series. Analysis is available for both annual and seasonal data. Data presentation defaults to national-scale aggregation, however sub-national data aggregations can be accessed by clicking within a country, on a sub-national unit. Other historical climatologies can be selected from the Time Period dropdown list.
Observed, historical data is produced by the Climatic Research Unit (CRU) of University of East Anglia. Data is presented at a 0.5º x 0.5º (50km x 50km) resolution.
Due to its location in the western area of the Pacific, and the strong influence of the northeast trade winds (which generally prevail December through April), FSM experiences a tropical climate. FSM experiences little seasonal variation in mean air temperatures across the year (less than 1.5°C between the average hottest and coolest months) which is driven mainly by sea surface temperatures around the islands. In general, across the island group, the mean annual temperature averages 27.1°C over the period 1901-2019.
Rainfall is high on the volcanic islands of Kosrae, Pohnpei and Chuuk primarily during the wet season from May to November when the Intertropical Convergence Zone (ITCZ) is strongest and furthest north, with annual totals exceeding 400 inches (1,016 cm) and up to 22 inches (559 mm) in a given day. Western islands receive additional rain due to the West Pacific Monsoon. The islands, especially within the western states, are generally affected by storms and typhoons, as well as excessive rainfall and drought as associated with the warm and cold phases of the El Niño- Southern Oscillation (ENSO). The most western state of Yap is in an area affected by a monsoon climatic pattern and can tend to experience more frequent periods of drought.
Relative to the other states, Yap receives the least rainfall, with annual averages of around 122 inches (3,100 mm); Chuuk receives about 140 inches (3,556 mm), Pohnpei receives just under 190 inches (4,826 mm), and Kosrae receives around 203 inches (5,156 mm). However, it is noted that the mountainous interior of Kosrae may receive as high as 300 inches (7,500 mm).