The Red Flag Warning has been sounded by Alberta Wildfire. But what does it mean? It means conditions are ripe for the ignition and fast-moving spread of wildfires. The forest-fire experts use a sliding scale, first adopted by the U.S. National Weather Service, to determine how dry the conditions are in the forest areas, and how the wind could help fan the flames if that dry tinder is ignited. Basically, a score is calculated based on wind speed, heat and the lack of humidity. A sample document provided by Alberta Wildfire shows a hypothetical watch being created when the maximum daily temperatures is expected to hit 33 Celsius, the humidity is at 25 per cent or lower, and wind speeds are 10 km/h. Basically, when it is punishingly hot and dry, it doesn’t take a lot of wind to trigger an alert. “And, just like weather alerts, “watch” is one level below “warning.”