The Irish driver kept it cool in the light shower and completed the race in a time of 21 minutes 35.700 seconds, comfortably ahead of Sami Meguetounif who was timed at 21:38.798s.
Finland’s Elias Seppanen, winner of the first race on Friday, had to settle for third spot in 21:38.818s.
Commenting on the race, Allen said he didn’t have any issues battling in the rain, adding that in fact the win would inspire him for the remaining two races today.
“You have to remain calm when competing in wet conditions. I’m used to this and so it was no problem for me today.
“This is definitely a great start for me and I’m excited looking forward to the other races,” said Allen.
Races 3 and 4 will be held later today.