The sun path is the arc the sun traces across the sky from sunrise to sunset. The arc sits high in summer and low in winter.

The sun path decides which parts of a garden get direct sun and at what hours. It decides how far a fence, tree or house shadow reaches. It also decides whether a bed that is in full sun in July is still in sun in December. Every awning, shade sail and pergola is sized against it.

How the sun's position is measured

Two angles fix the sun's position at any moment. NOAA's Solar Position Calculator defines them as follows.

  • Azimuth: the compass direction of the sun, in degrees measured clockwise from north. 0° is north, 90° is east, 180° is south and 270° is west.
  • Elevation (altitude): the height of the sun, in degrees measured up from the horizon. 0° is the horizon. 90° is directly overhead.

Through a single day, azimuth sweeps from the sunrise point to the sunset point. Elevation climbs to its highest value at solar noon and then falls.

Through the year, the whole arc moves up and down. The cause is the tilt of Earth's axis, about 23.45° according to NOAA's solar equations paper. The variable that carries this tilt into the calculation is the solar declination. Declination is the sun's angle north or south of Earth's equatorial plane. It changes a little every day, so the sun's path shifts gradually rather than in jumps. A positive declination means the sun is toward the Northern Hemisphere.

Declination has three reference values:

  • June solstice: about +23.5°.
  • March and September equinoxes: 0°. The sun is crossing the celestial equator.
  • December solstice: about −23.5°.

The Yield Grid gives the noon elevation as 90° − |latitude − declination|. For a northern garden where latitude is greater than declination, this reduces to noon elevation = 90 − latitude + declination. Shadow length is the object's height divided by the tangent of the elevation.

A 20 ft (6.1 m) house at 45°N

Latitude is 45°. Noon elevation is 90 − 45 + declination. Shadow length is 20 ft ÷ tan(elevation).

June solstice (declination +23.5°)68.5° elevation, shadow 7.9 ft (2.4 m)
Equinox (declination 0°)45° elevation, shadow 20 ft (6.1 m)
December solstice (declination −23.5°)21.5° elevation, shadow 50.8 ft (15.5 m)

The December noon shadow is about 6.4 times the June noon shadow. The Yield Grid gives the same 7.9 ft and 50.8 ft figures.

This guide does not list figures for specific cities. To get figures for a garden, enter its location and date in NOAA's Solar Calculator. NOAA states that the calculator is "no longer actively supported or maintained" and is "for research and entertainment purposes only". The equations it uses are published in the NOAA paper linked above.

Where the sun path shows up

Winter shadows. Shadow length rises sharply as latitude rises. The Yield Grid gives noon shadows for a 10 ft (3.0 m) object:

  • 45°N: 4.0 ft (1.2 m) in summer and 25.4 ft (7.7 m) in winter, 6.4 times longer.
  • 55°N: 6.1 ft (1.9 m) in summer and 49.1 ft (15.0 m) in winter, 8.0 times longer.
  • 65°N: 8.8 ft (2.7 m) in summer and 382 ft (116.4 m) in winter, 43.4 times longer.

The formula stops working above about 66.5° latitude. Above that line there are days with no sunrise or no sunset. One backyard fence measured by Koren Helbig cast 0.5 m (1.6 ft) of shadow in summer and 4.6 m (15.1 ft) in winter.

The equinox. On the equinox the sun rises due east and sets due west. Lowell Observatory notes that this happens on only two days a year. The 2026 September equinox fell at 5:05pm MST on September 22. That is 00:05 UTC on September 23: 8:05pm EDT on September 22, and 1:05am BST on September 23. After it, the sunrise and sunset points move farther south each day until the December solstice.

The Southern Hemisphere. The formula still applies with latitude entered as a negative number. At 35°S, noon elevation is 78.5° in December and 31.5° in June. In the Southern Hemisphere, December is summer and June is winter. A 40 ft (12.2 m) tree at 35° casts a noon shadow of 8.1 ft (2.5 m) in its summer and 65.3 ft (19.9 m) in its winter. At a southern site whose latitude is greater than the declination, the noon sun stands to the north, not the south.

What it is not

Often taken for The difference
Magnetic compass north Solar azimuth is measured from north. Lowell Observatory points to the equinox sunrise and sunset as a check on true solar directions rather than magnetic ones.
Exactly 12 hours of daylight on the equinox Day length is slightly longer. The Old Farmer's Almanac gives 12 hours 8 minutes for Dublin, New Hampshire, on the 2026 equinox, because of atmospheric refraction.
Noon sun as a measure of daily sun Noon elevation gives the shortest shadow of the day. It does not give the number of hours a spot is in sun.
Meteorological seasons Meteorological autumn is September to November in the Northern Hemisphere. The sun path follows astronomical dates, which are set by the equinoxes and solstices.

Sources: The Old Farmer's Almanac for day length, Royal Museums Greenwich for the definitions of the seasons.

Using it before you build

If a feature is permanent, check it against the December sun first. In the Southern Hemisphere, check it against the June sun first. A pergola, raised bed, greenhouse or fruit tree is permanent. The Yield Grid calls the winter result "your binding constraint".

The checks, in order:

  1. Find which way the garden faces and the hours of sun each season gives it.
  2. Find the latitude of the garden.
  3. Work out the noon elevation for both solstices with 90 − latitude + declination.
  4. Divide the height of each fence, tree and wall by the tangent of each elevation.
  5. Measure that distance out from the object, on the side away from the sun.

If a bed falls inside the winter shadow, it is in shade at noon on that date. It is in shade for longer at other hours, because the sun is lower then.

For reference, Ideal Home defines full sun as at least 6 hours of direct sun, part shade as 4 to 6 hours and shade as less than 4 hours.