The very steep mountains on each of the main Hawaiian islands block the prevailing northeast trade winds. This results in abundant rain on the slopes facing the windward direction and dry “rain shadows” in the leeward areas. Maui's west coast tourist communities, including Lahaina, are in one of those rain shadows.

Lahaina’s dry climate is primarily the result of a "Rain Shadow" effect created by the West Maui Mountains (Mauna Kahalawai). As moist trade winds blow from the northeast, they hit the windward side of the mountains, rise, cool, and dump their rain on the peaks and the lush valleys of Iao. By the time the air crosses over to the leeward side where Lahaina sits, it has lost most of its moisture and descends as warm, dry air. This phenomenon makes Lahaina one of the sunniest and driest spots on Maui, historically earning it the name "Lele," meaning "relentless sun." In 2026, this dryness remains a significant environmental factor; the area receives very little annual rainfall compared to the rest of the island, which is why it was historically a primary location for sugar cane and pineapple cultivation that required heavy irrigation. This persistent dry state, combined with invasive, flammable grasses on the surrounding hillsides, also creates a permanent high-risk environment for wildfires, especially during periods of high "Downslope" winds and drought.