<p>ERA5 data for 30 years (1994–2023) were used to analyze the spatiotemporal climate characteristics of low-level jets (LLJs) over the Korean Peninsula. To assess the suitability of this data, ERA5 LLJ characteristics were compared with long-term radiosonde observations. Because ERA5 data represent grid-averaged atmospheric conditions, an additional LLJ-0 category [wind speed (<i>V</i>_<i>max</i>) &gt; 8&#xa0;m/s, wind speed decrease above LLJ altitude (△V) &gt; 4&#xa0;m/s] was defined as adjusted criteria. A comparison between LLJ-1 and LLJ-0 from the radiosonde observation and ERA5 data, respectively, confirmed similar monthly variations in frequency and altitude distributions. LLJ frequency varied regionally and seasonally. The highest frequency (40%) was observed in spring (April–May) in the West sea, whereas, in summer, the high-frequency region shifted to the South Sea. The LLJ altitude showed a clear contrast between land and sea. Over the sea, LLJs occurred extensively at low altitudes (0.8–1.2&#xa0;km), while, over land, LLJ altitude gradually increased from the west coast eastward, with the highest altitudes (&gt; 1.4&#xa0;km) found over the Taebaek Mountains. The LLJ wind direction showed two to three dominant modes in each region. Notably, year-round easterly LLJs occurred across inland regions. The ERA5 data did not adequately capture the wintertime northerly LLJ on the leeward side of Hallasan, Jeju Island. Although the 30-year dataset was insufficient to assess the climatic influences on LLJ frequency, it indicated an increase in LLJ frequencies over most regions except the east coast.</p>