Croatia is located in Central and Southeast Europe, bordering Hungary to the northeast, Serbia to the east, Bosnia and Herzegovina to the southeast, Montenegro to the southeast, the Adriatic Sea to the southwest and Slovenia to the northwest. Part of the territory in the extreme south surrounding Dubrovnik is a practical exclave connected to the rest of the mainland by territorial waters, but separated on land by a short coastline strip belonging to Bosnia and Herzegovina around Neum.

The territory covers 56,594 square kilometres (21,851 square miles), consisting of 56,414 square kilometres (21,782 square miles) of land and 128 square kilometres (49 square miles) of water. It is the 127th largest country in the world. Elevation ranges from the mountains of the Dinaric Alps with the highest point of the Dinara peak at 1,831 metres (6,007 feet) near the border with Bosnia and Herzegovina in the south to the shore of the Adriatic Sea which makes up its entire southwest border. Insular Croatia consists of over a thousand islands and islets varying in size, 48 of which are permanently inhabited. The largest islands are Cres and Krk, each of them having an area of around 405 square kilometres (156 square miles).

The hilly northern parts of Hrvatsko Zagorje and the flat plains of Slavonia in the east (which is part of the Pannonian Basin) are traversed by major rivers such as Sava, Drava, Kupa and Danube. The Danube, Europe's second longest river, runs through the city of Vukovar in the extreme east and forms part of the border with Serbia. The central and southern regions near the Adriatic coastline and islands consist of low mountains and forested highlands. Natural resources found in the country in quantities significant enough for production include oil, coal, bauxite, low-grade iron ore, calcium, gypsum, natural asphalt, silica, mica, clays, salt and hydropower.

Karst topography makes up about half of Croatia and is especially prominent in the Dinaric Alps. There are a number of deep caves in Croatia, 49 of which are deeper than 250 m (820.21 ft), 14 of them deeper than 500 m (1,640.42 ft) and three deeper than 1,000 m (3,280.84 ft). Croatia's most famous lakes are the Plitvice lakes, a system of 16 lakes with waterfalls connecting them over dolomite and limestone cascades. The lakes are renowned for their distinctive colours, ranging from turquoise to mint green, grey or blue.

Most of Croatia has a moderately warm and rainy continental climate as defined by the Köppen climate classification. Mean monthly temperature ranges between -3 °C (27 °F) (in January) and 18 °C (64 °F) (in July). The coldest parts of the country are Lika and Gorski Kotar where snowy forested climate is found at elevations above 1,200 metres (3,900 feet). The warmest areas of Croatia are at the Adriatic coast and especially in its immediate hinterland characterised by the Mediterranean climate, as the temperature highs are moderated by the sea. Consequently, temperature peaks are more pronounced in the continental areas—the lowest temperature of -35.5 °C (-31.9 °F) was recorded on 3 February 1919 in Cakovec, and the highest temperature of 42.4 °C (108.3 °F) was recorded on 5 July 1950 in Karlovac.

Mean annual precipitation ranges between 600 millimetres (24 inches) and 3,500 millimetres (140 inches) depending on geographic region and prevailing climate type. The least precipitation is recorded in the outer islands (Vis, Lastovo, Biševo, Svetac) and in the eastern parts of Slavonia, however in the latter case, it is mostly occurring during the growing season. The maximum precipitation levels are observed on the Dinara mountain range and in Gorski kotar.

Prevailing winds in the interior are light to moderate northeast or southwest, and in the coastal area prevailing winds are determined by local area features. Higher wind velocities are more often recorded in cooler months along the coast, generally as bura or less frequently as sirocco. The sunniest parts of the country are the outer islands, Hvar and Korcula, where more than 2700 hours of sunshine are recorded per year, followed by the southern Adriatic Sea area in general, northern Adriatic coast, and Slavonia, all with more than 2000 hours of sunshine per year.