Hay Slough Fire

201586,165 acresAlaska

The Hay Slough Fire burned 86,165 acres, about 135 square miles, across Yukon-Koyukuk Census Area. It began on June 21, 2015.

Watch how it happened

Hay Slough Fire · 2015

How it happened

Watch it burn in the order satellites saw it, coloured by how severely each place burned.

About this replay

Date (UTC)—Historical replay

Burned so far—acres

High severity—of the area so far

Detections3,157satellite fire pixels

Fire milestones

Burn severityHigh, Moderate, Low, Unburned to low, Increased greenness

Burning nowAreas reached in the last half day of satellite passes

Washington, D.C., to scale61 square miles of land, drawn at the fire’s scale

Timing: NASA FIRMS satellite fire detections (2,659 VIIRS and 498 MODIS) inside the final perimeter; each place takes the time of its nearest detection, so the order is satellite-observed but interpolated between passes, roughly every 12 hours. Severity: Monitoring Trends in Burn Severity (USGS, U.S. Forest Service), mapped from Landsat after the fire.

How severely it burned

Burn severity inside the final perimeter, classified from Landsat images taken before and after the fire.

Map of burn severity across the Hay Slough Fire

Burn severity by class
Severity	Share	Acres
Highmost vegetation consumed, soils altered	20%	17,275
Moderatemixed: many trees killed, some survive	29%	25,076
Lowsurface fire, most trees survive	19%	16,658
Unburned to lowislands inside the perimeter, little change	11%	9,107
Increased greennessvegetation greener after the fire than before	0.5%	403
Not mappedcloud, shadow or water in the satellite images	20%	17,647

20% of the area inside the perimeter burned at high severity, about 17,275 acres; 49% burned at moderate or high severity.

Monitoring Trends in Burn Severity (U.S. Geological Survey and USDA Forest Service). Classes come from the change in a Landsat burn index (dNBR) between images before and after the fire; acres are each class’s share of the fire’s mapped area.

Where it burned

Acres inside each county, measured from the satellite-mapped perimeter.

Acres burned by county

Yukon-Koyukuk Census Area	AK	86,219

Other large fires in Alaska in 2015

Middle Yukon Fires407,220 acres
Tobatokh Fire220,037 acres
Isahultila Fire192,663 acres
Holtnakatna Fire180,199 acres
Tanana Area Fires176,773 acres
Rock Fire142,933 acres
Big Mud River 1 Fire140,914 acres
Munsatli 2 Fire124,572 acres

Monitoring Trends in Burn Severity (USGS and U.S. Forest Service). Type recorded: Wildfire.