A difficult fire season in western Canada brought its impacts to coastal city streets in early July 2015. A thick pall of smoke settled over Vancouver and adjacent areas of British Columbia, leading some residents to wear face masks and health officials to warn residents and World Cup tourists against outdoor activities.

The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite acquired these images in the late morning on July 5 and 6. Note how the tan and gray smoke almost completely obscures the Strait of Georgia and southern Vancouver Island. Winds shifted abruptly between July 5 and 6, driving the smoke plume toward the east, dispersing it in some places while fouling the air in areas to the east, such as the Fraser Valley.

In the images, the principal source of the smoke appears to be fires burning 100 to 150 kilometers north of the city of Vancouver and roughly 50 to 70 kilometers north and west of Pemberton and the ski resort area of Whistler. The Elaho Valley fire was sparked by lightning in mid-June 2015, and stayed relatively small and contained until it started growing vigorously on July 4. By the morning of July 7, the fire and its scar covered about 20,000 hectares (50,000 acres), and the blaze was uncontrolled on all fronts. Fire managers reported crown fires—blazes high in the forest canopy that can leap across areas quickly when fanned by winds. Thick smoke and gusty winds prevented airborne firefighting flights on July 6, according to news reports.

To the northeast of the Elaho fire, the Boulder Creek Wildfire Complex also exploded, growing tenfold in a day. Firefighters estimate that the blaze spans at least 5,500 hectares (13,500 acres); it is not contained on any front. To the east (not in the image), the Cougar Creek fire has claimed 5,000 hectares (12,000 acres).

Western Canada and Alaska have been plagued by an intense fire season that started earlier than normal (usually late July). Below-average winter snowfall and extreme spring and early summer temperatures have left a vast region dry, hot, and primed for fire. As of July 7, 2015, at least 182 reported wildfires were burning in British Columbia; 23 of them were sparked on July 6 alone.

According to Canadian fire officials and news reports, there have been 841 fires in the province since April 1, and nearly half of them have been started by lightning. Observers in Canada and Alaska have noted higher than usual numbers of lightning strikes.

NASA images by Jeff Schmaltz, LANCE/EOSDIS Rapid Response. Caption by Mike Carlowicz.