Estonia occupies 45,227 square kilometers on the eastern shore of the Baltic Sea. The country shares a 294-kilometer border with Russia to the east and a 333-kilometer border with Latvia to the south. The Baltic Sea forms 768 kilometers of coastline along Estonia's western and northern edges. The Gulf of Finland extends along the northern coast from the Russian border to the West Estonian Archipelago. The Gulf of Riga indents the southwestern coast between the mainland and Saaremaa. No point in Estonia lies more than 50 kilometers from the sea or a major lake.
The terrain consists of lowland plains with average elevation 50 meters above sea level. The Haanja Upland rises in southeastern Estonia near the town of Võru. Suur Munamägi reaches 318 meters in the Haanja Upland, making it the highest point in Estonia and the highest point in the Baltic states. The summit sits 3 kilometers from the Latvian border. A 29-meter observation tower built in 1939 stands on Suur Munamägi, raising visitors to 347 meters above sea level. The upland formed from sedimentary deposits during the Devonian period 370 million years ago, later shaped by glacial movement during the Weichselian glaciation that ended 11,700 years ago.
Water covers 2,839 square kilometers of Estonia's territory. Lake Peipus forms the eastern border with Russia across 3,555 square kilometers, making it the fourth-largest lake in Europe by surface area. Estonia controls approximately 44 percent of Lake Peipus on the western shore. The lake reaches maximum depth of 15 meters with average depth 7 meters. Three distinct sections comprise the lake system: Lake Peipus proper in the north (2,611 square kilometers), Lake Lämmijärv in the center (236 square kilometers), and Lake Pihkva in the south (708 square kilometers, mostly in Russia). The Emajõgi River flows 101 kilometers from Lake Võrtsjärv to Lake Peipus, draining central Estonia. Lake Võrtsjärv covers 270 square kilometers in central Estonia with maximum depth 6 meters and average depth 2.8 meters. The Narva River flows 77 kilometers from Lake Peipus north to the Gulf of Finland, forming most of the Russian border.
The West Estonian Archipelago contains more than 2,200 islands and islets. Saaremaa covers 2,673 square kilometers, making it the largest island in Estonia and the fourth-largest island in the Baltic Sea. The population of Saaremaa was 31,435 in the 2021 census. Kuressaare, the only town on Saaremaa, had 13,276 residents in 2021. Hiiumaa covers 1,032 square kilometers with 9,584 residents in 2021. Muhu covers 198 square kilometers between Saaremaa and the mainland, connected to Saaremaa by a 3-kilometer causeway built in 1896. Vormsi covers 93 square kilometers with 323 residents in 2021. Kihnu covers 16.4 square kilometers in the Gulf of Riga, inhabited by 670 residents in 2021 who maintain distinct cultural traditions recognized by UNESCO. Ruhnu covers 11.9 square kilometers in the Gulf of Riga, 52 kilometers from the mainland with 64 residents in 2021. The Pakri Islands sit 3 kilometers off the northwestern coast near Paldiski. Osmussaar rises 8 kilometers off the Pakri Peninsula.
Limestone bedrock underlies northern and western Estonia. The limestone plateau formed during the Ordovician period 450 million years ago when shallow seas covered the region. Exposed limestone cliffs rise along the northern coast at Ontika, where the cliff face reaches 56 meters above the Gulf of Finland. The Käsmu Boulder Field on the Lahemaa coast contains thousands of erratic boulders deposited by retreating glaciers. Individual boulders exceed 10 meters in diameter. The Kaali meteorite crater on Saaremaa formed approximately 3,500 years ago when a meteor estimated at 20 to 80 metric tons struck the island. The main crater measures 110 meters in diameter and 22 meters deep. Eight smaller craters surround the main impact site within a 1-kilometer radius.
Forests cover 2.2 million hectares, representing 51 percent of Estonia's land area according to 2020 data from the Estonian Environment Agency. Pine forests dominate sandy soils in coastal areas and on islands. Spruce forests grow in fertile central and southern regions. Birch forests develop in transitional zones and previously cleared areas. Alder grows in wetlands along rivers and lake shores. Oak reaches its northern distribution limit in Estonia, growing primarily on Saaremaa and in southern counties. The oldest documented tree in Estonia is a 750-year-old pedunculate oak in Orissaare parish on Saaremaa, measured in 2015 with circumference 8 meters and height 17 meters.
Bogs and wetlands cover 1 million hectares, representing 22 percent of Estonia's territory. Raised bogs formed over 10,000 years as sphagnum moss accumulated in depressions left by retreating glaciers. Peat deposits in Estonian bogs reach depths of 10 meters in some locations. Soomaa National Park contains 37,000 hectares in southwestern Estonia where spring flooding from snowmelt creates temporary lakes called the "fifth season" by residents. Water levels in Soomaa rise 2 to 5 meters during spring floods, typically peaking in late March or early April. The flooding lasts two to six weeks depending on snowpack and temperature. Endla Nature Reserve protects 10,100 hectares of raised bogs, wooded meadows, and transition mires in central Estonia. Nigula Nature Reserve covers 6,421 hectares of raised bog in southwestern Estonia near Pärnu.
The climate follows a transitional pattern between maritime and continental influences. The Baltic Sea moderates temperatures in coastal areas while the interior experiences greater seasonal variation. January mean temperatures range from minus 3.5 degrees Celsius on the coast to minus 7 degrees Celsius in the interior according to 1991-2020 climate normals from the Estonian Weather Service. July mean temperatures range from 16.3 degrees Celsius on the coast to 17.8 degrees Celsius inland. The absolute maximum temperature of 35.6 degrees Celsius was recorded at Võru on August 11, 1992. The absolute minimum temperature of minus 43.5 degrees Celsius was recorded at Jõgeva on January 17, 1940.
Annual precipitation averages 700 millimeters across Estonia with regional variation from 550 millimeters in eastern areas to 800 millimeters on elevated terrain in the southeast. Precipitation distributes relatively evenly through the year with slight peaks in late summer and autumn. Snow cover persists 90 to 140 days per year depending on location. Coastal areas average 90 days of snow cover while southeastern uplands average 140 days. The snow depth averages 20 to 30 centimeters but can exceed 50 centimeters during heavy winters. The Baltic Sea freezes partially during most winters. In severe winters the ice extends from shore 20 to 40 kilometers into the Gulf of Finland and completely covers the Gulf of Riga. Ice roads connecting islands to the mainland operated regularly until the 1990s. The official ice road between Haapsalu and Noarootsi operated until 1996. Unofficial ice roads still form between smaller islands during cold winters.
Wind patterns vary seasonally with prevailing westerly and southwesterly winds bringing maritime air from the Atlantic. Mean wind speed averages 3 to 5 meters per second across most of Estonia. Coastal areas and islands experience higher average wind speeds of 5 to 7 meters per second. Storm winds exceeding 20 meters per second occur 10 to 30 days per year. The strongest measured wind gust of 48 meters per second was recorded at Vilsandi on January 3, 1976. The Baltic Sea influences cloud cover, resulting in 1,600 to 1,900 hours of sunshine annually. Saaremaa receives the most sunshine with annual totals exceeding 1,900 hours. Interior locations receive 1,600 to 1,700 hours annually. November averages 27 hours of sunshine while June averages 310 hours.