Mountain light: when the Rockies take the sun.

The time printed for sunset is when the sun meets a flat, level horizon. Standing on an acreage in the foothills, you face the Front Ranges, which stand a degree or three above that level line. The sun disappears behind them before the official sunset, and how much earlier depends on where you are.

Winter solstice

7–17 min earlier

Longest daily gap

19 min · Bragg Creek

Regions · days each

11 · 365

Across the 11 regions, direct sun ends between about 7 and 17 minutes before the official sunset on the winter solstice, December 21. The pattern is not simply a winter one. In Bearspaw the summer solstice costs about 15 minutes, more than the winter solstice's 9, because the June sun sets farther north, where the skyline it faces (1.5° above level) is higher than in the south-west (0.9°).

Each region's page shows the skyline it faces and its own year of sun, and the numbers below come from the same computed terrain.

Every region compared

Reading it for land

• Low sun is weak sun. In the last minutes before sunset the light crosses far more air and arrives at a shallow angle, so it carries much less light and heat than at midday. These are minutes of low sun, but they are when a west-facing deck, window or driveway slope still catches the day's last direct light.
• Your lot is not the regional average. Each figure uses the highest bare ground near the region's centre. A site in a creek valley, at the foot of a west-side slope or behind a stand of spruce loses direct sun earlier; a site on a west-facing rise loses it later.
• See it at the hour that matters. A showing at noon in July says nothing about a December afternoon. If winter evenings on the deck are part of the picture, visit in the season and at the hour you care about.
• Solar panels or a large garden need a site-specific answer. This page does not estimate energy output or growing conditions. Ask a qualified installer or designer for a shade analysis of the exact spot.
• It is not a judgement of value or suitability. It is one measured fact about the land, set beside the others on the regional pages.

How it is computed

1. The skyline. From each region's high-ground viewpoint, rays are cast every tenth of a degree from due south through west to due north, out to 150 km across the elevation model, allowing for the curve of the earth and standard refraction. The result is the highest apparent angle in every direction. The same data draws the skyline panorama on each region page.
2. The sun. The sun's position uses the NOAA calculation from Jean Meeus's Astronomical Algorithms, accurate to about a hundredth of a degree. Its upper edge, with atmospheric refraction, is followed in ten-second steps through every afternoon of 2026.
3. Two moments. Official sunset is when the sun's upper edge reaches a flat, level horizon. Direct sun ends is the last moment that edge is above the computed skyline in its direction. The difference is the minutes lost. On some days the sun slips behind a peak and reappears; the figure is the final loss.
4. A check. The flat-horizon sunsets from this calculation match the U.S. Naval Observatory's Calgary instants to the minute when expressed in this model's Alberta clock rule: winter solstice (5:32 pm), spring equinox (7:50 pm), summer solstice (9:55 pm) and autumn equinox (7:34 pm).