On August 2, the Japan Meteorological Agency (JMA) began to monitor a tropical depression which developed over the Philippine Sea. The system slowly developed while moving northward. The Joint Typhoon Warning Center (JTWC) also monitored the system and gave the identifier "10W" early on August 4. The JMA upgraded the system to a tropical storm and assigned the name "Lekima" at 6:00 a.m. UTC that day. The JTWC followed suit later that day. Though Lekima was affected by moderate wind shear, warm waters of and good outflow channel allowed Lekima to slowly intensify, and Lekima became almost stationary due to the absence of steering current.