The skies opened at Sepang in between Friday's first and second practice sessions.
The initial 90 minute session occurred in hot and humid conditions.
Then, about an hour before the second session scheduled for 2pm, a heavy downpour of rain struck the circuit, which is located about a 20-minute drive from the heart of Kuala Lumpur.
The rain quickly passed and the sun remerged, but the track is still wet with 30 minutes to go until FP2.
As the paddock inhabitants were ducking for cover at lunchtime, team bosses had been summoned to a meeting with Bernie Ecclestone, and the FOTA group is scheduled to meet at 4.30pm.