Why fog is hard to predict
Humidity alone isn't enough. Wind alone isn't enough. Cloud cover alone isn't enough. Photogenic valley fog requires several conditions to line up at once, and most weather apps don't read them together.
Dew Point Depression
When air temperature and dew point converge below 2°C, the air is near saturation. This is the single strongest fog predictor and the first thing FogCast checks.
Wind Speed
Fog needs calm air. Below 5 km/h is ideal. Above 15 km/h, fog disperses before it can pool in the valley. A standard weather app won't flag this combination.
Overnight Sky Clarity
Clear overnight skies let the ground cool rapidly, pushing surface temperatures toward the dew point. Counterintuitively, clouds overnight suppress radiation fog.
Temperature Trend
FogCast reads the overnight temperature arc. If temps are converging toward the dew point hour by hour, fog probability increases significantly by pre-dawn.
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Fog photography at Banff
Banff National Park in the Canadian Rockies combines glacially fed lakes, dramatic mountain peaks, and cold valley floors that produce some of the most photogenic fog in North America. The Bow Valley floor at Banff townsite sits at 1,383 meters, and cold air drains off the surrounding peaks overnight, pooling in the valley and often producing dense radiation fog that fills the corridor while the mountain tops remain clear.
Lake Minnewanka and the Vermilion Lakes are the most atmospheric fog locations near the townsite. The Vermilion Lakes at dawn with fog over the water and Mount Rundle reflecting in the calm surface is one of the classic Canadian Rockies compositions. The Bow River corridor and the Banff Springs Hotel overlooks also offer strong fog compositions when the valley fills with mist.
Fall is the best season, from late September through November, when overnight temperatures drop sharply and the larch trees at higher elevations are golden. Valley fog is most reliable after clear, calm nights following days with high humidity. The window before sunrise is critical: valley fog in Banff can burn off quickly once the sun reaches the valley floor.
Frequently asked
Can I check FogCast on the website?
This page shows a preview of current conditions, including humidity, wind, temperature, and dew point. The full FogCast score, 7-day outlook, push notifications, and best shooting windows are available exclusively in the LightCast app for iOS.
Is FogCast free?
The current conditions preview on this page is free, no account needed. The full FogCast tool is in the LightCast Suite iOS app, which includes a 7-day free trial. After the trial it's $2.99/month, cancel anytime in the App Store.
Why use FogCast instead of checking humidity?
Humidity alone doesn't tell you whether photogenic fog is likely. High humidity with strong wind produces no fog at all. FogCast combines dew point depression, wind speed, overnight sky clarity, temperature trend, and visibility into a single score built specifically for fog photography planning.
What is FogCast's scoring scale?
FogCast scores fog conditions from 0 to 100. A score of 75 or above indicates dense fog is expected. 55 to 74 means fog is likely and worth chasing. 35 to 54 suggests patchy mist is possible. Below 35, conditions are unlikely to produce photogenic fog. The full score is available in the LightCast app.