How Sun Direction Changes by Season

Understand why sunrise, sunset, solar altitude, and facade exposure change during the year, and how to compare dates without relying on compass myths.

Last reviewed August 8, 2026

A direction such as south-facing or west-facing is only the beginning of a sunlight estimate. Latitude, season, time of day, and nearby obstructions determine whether direct sun reaches a real surface.

Start with true north and latitude

SunCarta reports azimuth clockwise from true north: east is 90°, south is 180°, and west is 270°. A phone may instead show magnetic north, so confirm its compass setting before comparing a field measurement with the map.

Latitude changes the height and side of the sky through which the sun travels. Near the tropics, the noon sun can appear north or south of a location during different parts of the year. At higher latitudes, seasonal differences in day length and solar altitude become much larger.

Compare representative dates

One date cannot describe a home or garden for the whole year. Compare a date near each solstice and at least one equinox, then add dates that matter for the real decision, such as a crop season, lease start, or event day.

Use the same receiving point and obstacle dimensions for every date.
Compare the time a shadow edge crosses the point, not only the daily total.
Treat sunrise and sunset as local civil times for the selected time zone.

Orientation does not replace obstruction geometry

Two windows with the same compass bearing can receive different direct sun because one is above a nearby roofline and the other faces a taller building. Add the closest material blockers and use measured or documented dimensions where possible.

For an outdoor horizontal point, direct sun is not limited by a window-facing direction. For a vertical window or facade, the sun must also be in front of that plane. SunCarta keeps those two cases separate.

Questions about this method

Does a south-facing window always receive the most sun?

No. That rule is hemisphere-specific and can be defeated by season, latitude, overhangs, trees, and nearby buildings. Model the exact location and dates instead.

Why can winter shadows be longer?

The sun often stays lower above the horizon in winter. For level ground, lower solar altitude produces a longer geometric shadow for the same obstacle height.