The disorganized system was located within favorable conditions for development, with sea surface temperatures in the area ranging from 30–31 °C (86–88 °F).

[3] At 18:00 UTC, the Japan Meteorological Agency (JMA) began issuing warnings on a tropical depression that had formed to the south of the Paracel Islands.

[7] Convection continued to deepen over the low-level circulation, and at 15:00 UTC, the JTWC upgraded the system to a tropical depression as it was located approximately 178 nautical miles (330 km; 205 mi) east-southeast of Da Nang, giving it the unofficial designation 08W.

[9] The convection became sheared to the southwest of the low-level circulation,[10] and on June 22 at 03:00 UTC, the JTWC upgraded Kujira to a tropical storm.

[11] At 12:00 UTC, Kujira peaked in intensity, with maximum sustained winds of 50 mph (85 km/h) and a minimum central pressure of 985 hPa (mbar; 29.09 inHg) as it made landfall on Hainan.

[5][b] The JTWC briefly downgraded Kujira to a tropical depression as it entered the Gulf of Tonkin on June 23 at 03:00 UTC.

[16] Flash floods killed 14 people, eight of which occurred in Sơn La Province, where rainfall of 280 millimetres (11 in) was recorded.

[28] Kujira enhanced the southwest monsoon in the Philippines, prompting the PAGASA to declare the beginning of the rainy season.