Nico Hulkenberg in the Renault logged the first time in FP3 with a 1:36.873 on the wet tyres.
Moments later, stablemate Carlos Sainz spun at turn 10 as the rain and track conditions got worse.
There was a long pause before car cames out and there was a flurry of laps towards the end of the session.
Initially, Sirtokin went 2nd and Ericsson 3rd behind Hulkenberg. Leclerc then took over at the top from the German as he posted a 1:36.447.
Sebastian Vettel, who was briefly on top, spun at turn 6 as the German went a bit deep into the hairpin.
Sauber had a great end to the session as Charles Leclerc and Marcus Ericsson ended up 1-2 at the end of FP3. Sirotkin, Vettel, Gasly, Hartley, Hulkenberg, Raikkonen and Stroll were the only other drivers to post a time in a fairly meaningless session.