Wildfire smoke, closures and heat can turn a trip around at the trailhead. Pick a park for a quick go / watch / wait read from live air quality, active NPS alerts and today's weather — straight from government sources.
No active alerts and healthy air on record. Conditions still change fast — glance again the morning you head out.
Conditions change by the hour. Always confirm on the official sources before you go — air quality at AirNow and alerts/closures on the official Haleakalā National Park page.