Scottish Daylight Hours Planner

Scottish daylight hours vary dramatically through the year. In Central Scotland, 21 June gives roughly 17 hours and 30 minutes between sunrise and sunset — go further north to Ullapool or Lochinver and it's over 18 hours, with genuine "never fully dark" skies around solar midnight. 21 December is the opposite: 6 hours 30 minutes of daylight in Glasgow, and even less on the far north coast.

That difference isn't just a curiosity. A 7-hour Munro day starting at 10am is fine in June. In December, the same walk finishes 30 minutes after sunset with no head torch — the definition of an unplanned epic. The daylight planner exists so you can sanity-check the start time of any Scottish hill day before you commit.

The calculator uses the NOAA Solar Calculator algorithm implemented in TypeScript directly in the page (no API calls, no external dependencies). It's accurate to ±1 minute at Scottish latitudes, which is well within the margin of error of the thing that actually matters on the hill (don't start the descent in fading light).

Civil twilight is the period when the sun is between 0° and 6° below the horizon — enough light to walk on a path without a head torch, but too dark for fine detail like map reading. Walking daylight is defined as civil dawn to civil dusk because that's the window you can plausibly walk in. Real daylight (sunrise to sunset) is usually 20–40 minutes shorter.

Times are automatically displayed in Europe/London time, so BST and GMT are handled correctly without you needing to think about it.

Walk window overlay: once you have your daylight data, enter a planned start time and estimated walk duration (paste it straight from the Naismith Calculator) to see a visual timeline of your route against the daylight window. The tool tells you how many minutes of margin you have before civil dusk — or how far over you'll run.