The three satellites were part of Canada's RADARSAT Constellation of Earth-observation satellites.
It was the second flight for the first stage, which was used in a mission last March.
The side boosters are expected to land at Landing Zone 2 and Landing Zone 1, the latter swept clear of the remains of SpaceX's unfortunate Crew Dragon.
Lift-off for the RADARSAT Constellation Mission-organized by the Canadian Space Agency (CSA)-will take place at the Vandenberg Air Force Base in California with the primary launch window opening at 7:17 a.m. PDT and closing shortly after at 7:30 a.m.
Vandenberg Air Force officials have confirmed the launch window for early Wednesday morning, and cautioned that residents in nearby counties - including San Luis Obispo County - might hear a sonic boom as the re-usable SpaceX rocket returns to the landing pad after launch. After starting the first stage of Falcon 9 made a successful landing back to Earth.
The Radarsat Constellation Mission satellites were deployed a few minutes apart from the upper stage about an hour after liftoff.
Working together, the RADARSAT satellites-built by Vancouver-based company MacDonald, Dettwiler and Associates, a subsidiary of Colorado firm Maxar Technologies-will monitor Canada's vast territory and the surrounding oceans daily, taking hundreds of thousands of images every year. This data will be used for marine disaster response, with the trio of satellites able to provide accurate pictures of weather and pollution activity, regardless of climate conditions or time of day.
"The (RADARSAT) spacecraft are meant to operate almost 400 miles up, where they will observe Canada's land and waters, as well as the Arctic". According to the Canadian Space Agency, the satellites will gather data for a variety of uses, primarily for maritime surveillance, disaster management and ecosystem monitoring.