The volunteer lifeboat crew of Cowes RNLI were tasked to launch at just before 05:00 and within minutes began searching the Solent. However, a second flare was soon spotted being fired from the shore.
Coastguard officers from The Needles and Newport then discovered spent flare cartridges in and around the Northwood Park area.
With no signs of any persons or vessels in distress, the lifeboat and Coastguard teams were stood down just as day dawned.
It is thought irresponsible youths may be behind the alert.