PORTLAND, Ore. (KATU) — It’s that time of year when wildfires start to pop up across the Pacific Northwest, spreading like well, wildfire. To help stay on top of fire season, meteorologists, forecasters, and agencies look to the skies for signs that a wildfire may spark. THE HOT-DRY-WINDY INDEX (HDWI) As the name suggests, the Hot-Dry-Windy Index assesses how weather conditions may affect a wildfire’s behavior based on three components: heat, moisture, and wind.