The rain came onto the course during the last two hours of the race.
For the general classification, Juan Ayuso was the fastest of the best placed. The Spaniard, 21, is 4th, 21 seconds behind McNulty. He is now ahead of Ilan Van Wilder by 7 seconds overall. The Russian Aleksandr Vlasov (BORA-hansgrohe) is 3rd at 10 seconds.
Thibau Nys (Lidl-Trek), 71st at 1:38. Friday, had donned the leader's yellow jersey after his victory in Thursday's mountain stage at the summit of Marécottes.
On Saturday, the second mountainous stage with five categorized passes will arrive in Leysin at the top of a 13.8 km pass at 6% after 159.2 km starting from Saillon.
This 77th edition of the Swiss race will end on Sunday in Vernier. Briton Adam Yates won last year. Claude Criquielion in 1986 is the last Belgian to have entered his name on the list.
