Coding classes in the Western Isles

The learner downloads the Stornoway file, a plain text table of monthly readings, and writes Python to read it. That alone teaches a lot: some months are missing and marked with dashes, some are provisional, and some are flagged with a # because an automatic sensor replaced the old Campbell-Stokes glass-ball recorder in September 2002. To keep the comparison fair, the learner averages each calendar month over 1991 to 2020 and leaves provisional months out. Then comes the key step: for every day of the year, compute the time from sunrise to sunset at latitude 58.2 degrees, and add them up month by month. That is the most sunshine the sky could possibly give.

May wins on both counts. It averages 193.1 hours of measured sunshine, far ahead of June's 149.5, even though June offers more possible hours, 543.4 against 518.9. As a share of what was possible, May reaches 37.2 per cent and June only 27.5. July is even cloudier by share, at 23.4 per cent, despite nearly the longest days of the year. At the dark end, December averages 25.6 hours, about an eighth of what the sky could give. The single sunniest month in the whole record is May 1994, with 294.1 hours; the dullest is December 2024, with just 6.8.

Why the share matters: comparing raw hours between June and December mixes two things, the weather and the length of the day. Dividing by the possible hours separates them, and that trick, dividing a count by its opportunity, runs through all good data work, from goals per match to reviews per sale. One caution the learner must keep: because the recording instrument changed in 2002, comparing decades across that switch mixes weather with equipment, so we compare months within the same period rather than across it.

So young people in the Western Isles should still learn to code in 2026: to know which question the numbers are really answering. The longer argument is in why teenagers should still learn to code in 2026.