Not cold, dude. I ride in the land of asphalt near Aloha Stadium, which keeps temps between the 70's and 80's.
Choose your engine well, grouchyolfart. You have the longest hill on Oahu, the one from Wahiawa to Haleiwa on the North Shore. Must be several miles uphill.
You should consider disc brakes because vee brakes might not last long on that downhill ride.
I would love to ride my bike from Wahiawa to Haleiwa, past Pipeline, Waimea Bay, then have lunch at the Kahuku shrimp wagons.
Then ride back to Wahiawa.
That's a 35-mile round trip with awesome scenery!