It's a bit hard to call it a microclimate when you're talking about places 60 miles apart, and the ring road peaks at ~2800' if you take the north way via Waimea or ~4000' if you take the south way via Kilauea, or ~6600' if you take the Saddle Road between Mauna Loa and Mauna Kea. There is, after all, a 13000' mountain in between the two sides of the Big Island.