Climate Change Overview

Country Summary

This page presents high-level information for Micronesia, Fed. Sts.'s climate zones and its seasonal cycle for mean temperature and precipitation for the latest climatology, 1991-2020. Climate zone classifications are derived from the Köppen-Geiger climate classification system, which divides climates into five main climate groups divided based on seasonal precipitation and temperature patterns. The five main groups are A (tropical), B (dry), C (temperate), D (continental), and E (polar). All climates except for those in the E group are assigned a seasonal precipitation sub-group (second letter).  Climate classifications are identified by hovering your mouse over the legend. A narrative overview of Micronesia, Fed. Sts.'s country context and climate is provided following the visualizations.

Köppen-Geiger Climate Classification, 1991-2020
  • Af
  • Am
  • As/Aw
  • BWh
  • BWk
  • BSh
  • BSk
  • Csa
  • Csb
  • Csc
  • Cwa
  • Cwb
  • Cwc
  • Cfa
  • Cfb
  • Cfc
  • Dsa
  • Dsb
  • Dsc
  • Dsd
  • Dwa
  • Dwb
  • Dwc
  • Dwd
  • Dfa
  • Dfb
  • Dfc
  • Dfd
  • ET
  • EF

The Federated States of Micronesia (FSM) is a widely dispersed archipelago located in the western part of the North Pacific Ocean. Comprised of what was generally known as Eastern and Western Caroline Islands, FSM is formed of four states (Yap, Chuuk, Pohnpei, and Kosrae, from west to east) over 607 islands, of which 74 are inhabited, covering the largest and most diverse part of the greater Micronesian region. There is a wide spread across the islands of FSM – there are 1,700 miles (2,700 kilometers [km]) between islands in the western-most state of Yap and islands in the eastern-most state of Kosrae. The capital of FSM, Palikir, is located in the eastern state of Pohnpei. The total land area of FSM is only 271 square miles (702 km2) but its exclusive economic zone (EEZ) covers an area of over one million square miles (2.5 million km2). There is also a range of island types within FSM – many of the islands are extinct volcanic shields with elevations up to about 2,500 feet (760 meters [m]) and dense vegetation interiors, but some islands are “flat, small and swampy, with low-lying, forested atoll islets, typically one to five meters above mean sea level flat”.

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), the Federated States of Micronesia experiences a tropical climate. Rainfall is high on the volcanic islands of Kosrae, Pohnpei and Chuuk primarily from May to November, with annual totals exceeding 400 inches (1,016 centimeters [cm]) and up to 22 inches (559 millimeters [mm]) in a given day. 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.

FSM’s estimated population reached a 100,000 as of 2020. The majority of the country’s population live in the coastal regions of the high islands, with more than half the population living in rural areas. 

Climate change poses significant threats for FSM development especially from accelerated sea-level rise, with its immediate coastal areas the most heavily-developed and little scope to move in-land. Like other Pacific Islands, climate change has contributed towards a significant increase in extreme weather events experienced by FSM, with number, intensity and impact of these events forecasted to rise.