Coding and AI classes in the West Midlands region

The learner averages each calendar month at Shawbury for two thirty-year spans, then places each monthly mean on the 15th of its month. Between two neighbouring months the temperature is assumed to change in a straight line. Where that line crosses the threshold, simple proportion gives the day: if March sits at 5.4 and April at 7.5, a 5.5 degree line is crossed a small fraction of the way from mid March to mid April. The program finds the spring crossing, the autumn crossing, and the number of days between them.

Every month at Shawbury is warmer in the later period, by between about 0.4 and 1.2 degrees, and that shifts the spring crossing earlier and the autumn one later. At the 5.5 degree line the season has grown by about 25 days, starting roughly two weeks sooner and ending about ten days later. The choice of threshold matters: moving it by half a degree changes the length by over two weeks, which is why any growing-season figure must state its threshold. These are simplified estimates from monthly means; official definitions count runs of warm days in daily data.

Now the lazy method. Count only the months whose mean is above 5.5 and call each one a full month. For 1961 to 1990 March averages 5.36, just under the line, so the season is April to November, eight months. For 1991 to 2020 March averages 6.31, so it becomes nine months. A change of under one degree in March adds a whole month at a stroke, which is an artefact of the method, not the weather. Interpolation turns the jump into the smooth two-week shift it really is.

Asking how a number was calculated, not just what it is, is a lasting reason for a West Midlands teenager to keep coding in 2026. The longer argument is in why teenagers should still learn to code in 2026.