Due to the special geographical location and climatic conditions of the Yellow Sea and Bohai Sea, the hydro-meteorology is very important to the safety of shipping routes. This statistical analysis was conducted on the hydro-logical and meteorological characteristics of the Yellow Sea and Bohai Sea from 1993 to 2023 based on ERA-5 (the fifth-generation European Centre for Medium-Range Weather Forecasts Re-Analysis). The main conclusions are as follows: (1) In winter, northerly strong winds prevail over the Yellow Sea and Bohai Sea, with the average of 5.23 m/s. Ice formation on the sea surface is the main factor affecting navigation in winter. (2) Affected by the monsoon, the waves are larger in autumn and winter, with seasonal average wave heights of 0.80 m and 0.94 m. The waves are weaker in spring and summer, with seasonal average wave heights of 0.69 m and 0.56 m. The duration of waves in the south or southeast direction is longer in summer. (3) The temperature distribution in the past 30 years has fully demonstrated the comprehensive effect of monsoon and terrain. The highest monthly temperature occurs in August with an average of 24.88 °C. The lowest monthly average occurs in January, and the average is −2.23 °C. The temperature change at sea is one month later than on shore.