Wave: Main factors determining the hydrological routine of the Caspian Sea are the followings: climate, water stream, sea depth, depth relief and coastal ruggedness. Strong wave in the Caspian Sea emerges during northern and southern winds blown especially in autumn and winter months.

Northern Caspian differs significantly from other parts of the sea for wave regime. Waves here reach the highest rates in 15-20 m/s of wind velocity as a result of lesser depth. The greatest waves (up to 8 m) are observed in southern winds in the Middle Caspian and in border areas. The most intensive wave is observed in Absheron peninsula during north-western winds, while it is observed in comparatively northern areas during northern winds. Strong wave in north east Makhachkala occurs during south-eastern winds.

The choppiest regions of the Caspian Sea from the standpoint of tide are the followings: the territory from Derbent to Absheron on coastal zones, and sea area adjacent to Absheron threshold in open sea regions.

Streams: Stream making factors in the Caspian Sea are the followings: wind, fluctuation of sea water consistency, depth and underwater relief of the sea, coastal forms and water currents. The main process amongst the abovementioned factors is wind. Stream system emerging due to the joint effect of these processes is observed in the sea in practice.

Water circulation in the Caspian Sea has emerged due to average perennial hydrometeorological condition. In general current system is described as follows:

Northern winds which are prevalent the whole year on the sea create ground water streams which are divided into 2 tributaries moving through Absheron peninsula. Relatively heavier of them enters the south by moving through the peninsula, hence moves back again towards the Middle and Northern Caspian going through the coasts of Southern Caspian. The second tributary enters eastern coasts moving towards east of Absheron peninsula and joins here with primary branch. The combined stream entering Mangyshlag peninsula turns to west of peninsula side and thus cyclonic (anticlockwise) water circulation is created in Northern Caspian. Local anti-cyclonic (clockwise) currents exist also in the south of the sea between Absheron peninsula and outfall of the Kura river.

The highest velocity in Northern Caspian belongs to north-eastern and south-western streams (25 cm/s), while the north-western and south-eastern (13 cm/s) currents hold the lowest speed. Speed of streams for other directions changes in interval of 15-18 cm/s. Velocity of currents can reach 100 cm/s during its navigation.

South-eastern streams are prevalent through western coasts of Middle Caspian. Strong north-western winds create currents directed to the east from the coast, and to the north-west in open sea in the territory of Absheron peninsula due to the coastal influence.

The velocity of streams holds 10-20 cm/s during weak winds through the north of Absheron peninsula, while 30-40 cm/s during mild winds, and 60-100 cm/s during strong winds.

Southern streams with the velocity of 10 cm/s are prevalent in Southern Caspian in Baku archipelago district. Maximum current speed here (40-50 cm/s) was observed during strong north-western winds. Southern streams prevail in April-September through eastern coasts of the Southern Caspian. Velocity of streams here holds 15-30 cm/s during mild winds, and 50-60 cm/s during strong winds.

Water temperature: The temperature regime of the Caspian Sea is formed due to impact of annual changes heat balance elements. The basic heat source is short wave radiation entering from the sun.

The sea collects heat (accumulation) in Northern Caspian in May-August, and consumes in September-February. Heat balance in the Middle and Southern Caspian changes its sign in relation to the Northern Caspian

From the beginning of April water in Northern Caspian is getting warmer and reach 12°C in coastal zone on surface, 6-10°C in open sea. The temperature holds 9-10°C in the Middle Caspian, and 11-14°C in the Southern Caspian at this time. The excessive warmth of sea water occurs in April-May. The temperature reach 17-18°C in the end of season in the Northern Caspian, 13-14°C in the Middle Caspian, and 16-18°C in the Southern Caspian. The increase of temperature continues in June and reaches maximum level in the end of the month. The thermal regime of sea water is maintained till the end of August and the sea surface is characterized with temperature homogeny. Water surface temperature equals 23-24°C in the Northern and Middle Caspian, 25-28°C in the Southern Caspian. Furthermore minus temperature anomalies are also observed in the center of the sea during summer season. Especially, increase of temperature appears in eastern coasts when getting far from the shore. This process is observed in western coasts also which contains relatively lesser area.

The sea gets cold from early September. The water temperature holds 10°C -17°C in the Northern Caspian, 15 - 18°C in the Middle Caspian, and 19 - 21°C in the Southern Caspian in October. Water temperature on sea surface oscillates between 3-10°C in the north, and 16 -18°C in the south in November.

Surface temperature oscillation in the Caspian Sea for months:
1– Northern, 2–Middle, 3–Southern, 4–The whole sea

Water salinity: Caspian Sea water is oceanic which joined with the ocean in ancient time and is considered the remnant of ancient Paratethys Sea like the Mediterranean Sea, Black Sea and Sea of Azov. Age of the Caspian Sea as a separate water basin is believed to be 3-5 million years old.

Average salinity of the Caspian Sea water contains 12.85‰ (per mille). ( average ocean water contains 35 ‰). Low saltiness of the Sea is related with its being enclosed and large river inflows. The amount of carbonates and sulphates in the Caspian Sea water is more than ocean waters, however the amount of chlorides is lesser in comparison.

Water salinity of the Caspian sea fluctuates between 0.1 ‰ in river outfalls, 12 ‰ in the boundary of the Middle Caspian, and 13.4 ‰ towards eastern coasts of the Southern Caspian. The northern, eastern and western coasts of the area contain more limpid water.

Average salinity in the deep parts of the Caspian Sea in open sea holds 12.8 – 12.9 ‰. Water saltiness oscillates relatively towards the sea depth, rises approximately 0, 1 – 0.2 ‰. Water salinity in water area of the western coasts of the sea is comparatively less than that of eastern coast. The main reason of this is explained with the existence of Volga river inflow through the western coasts. Analogical condition appears due to inflow of Kura river in the Southern Caspian Sea as well.

Water salinity increases up to 11, 0 ‰ in the Middle Caspian in the north-west, and 13.4 ‰ in the south-east in winter. Water saltiness contains the same that is 12.8 -12.9 ‰ (on surface) in both Middle and Southern Caspian. However water salinity rises up to 13 ‰ in the eastern coasts of the Middle Caspian and in central areas.

Freeze rate: The shallow northern part of the Northern Caspian Sea freezes each year, however the rest deep portion of the sea freezes seldom. Ice formation territories, term and its further development are determined with atmospheric processes on the sea surface in winter. The whole surface of the Northern Caspian freeze in severe winter, while the areas nearly 3 m isobath freeze in mild winter. The hugest ice layer here is observed in January-February (thickness of slab ice holds 70-90 cm in sharp winter, 35-40 cm in mild winter).

Distribution areas of ices in the Caspian Sea during various winter seasons. (1 – mild, 2 – temperate and 3 – severe winter)

Ice creation in the Middle Caspian usually appears in the late November, in closed bays of eastern coasts. The primary local ices in the western coasts in Makhachkala-Niyazobay are observed during severe winter in the late November, and during mild winter in January. Ice thickness here contains 20-25 cm, and 40-45 cm in eastern coasts in the same latitude. Ice is not seen in the western coasts in hot winter at all.

The long term northern winds in the sharpest winter period carry floating ices to the Absheron peninsula through western coasts. Last time this event was observed in 1953/1954 winter, and hard slab ice emerged in the northern part of Absheron peninsula on February 5, 1954.

Ice in the Southern Caspian emerges occasionally. Ice creation in the western coasts appears in December-February, in the eastern coasts in the middle December

Ice existence period in the Caspian Sea oscillates in large interval. In normal winter seasons shallow coastal zones of the Northern Caspian are covered with ice for 60-140 days, while open sea districts are covered with ice for 10-40 days.