Most people check the forecast for rain before a ride, but experienced cyclists check the wind first, and the cycling score reflects that priority. The reason is physics: a cyclist spends most of their effort pushing air aside, and a strong headwind is like an invisible hill that never crests, cutting your speed dramatically for the same effort. Crosswinds bring a safety dimension too, shoving the bike sideways in gusts. The score therefore penalises rising wind sharply, because a strong wind will define a ride even on an otherwise dry, pleasant day.
Rain matters to cyclists differently than people assume. Light rain on a mild day is mostly a comfort issue, but the real problems rain brings are reduced grip and reduced visibility. Wet roads lengthen braking distances and make painted lines, manhole covers and fallen leaves genuinely slippery, so the score treats rain as a significant negative. Visibility cuts both ways: you see less, and drivers see you less, which is why the score factors it in and why lights and bright clothing matter far more in wet, grey conditions. Heavy rain compounds everything and adds the misery of cold, since a moving cyclist loses heat fast.
For cyclists, temperature is really about the feels-like figure rather than the raw number, because moving through the air creates its own wind-chill. A still ten degrees feels much colder at riding speed, and a wet ten colder still. The score uses the apparent temperature and treats a mild band, roughly the mid-teens to low twenties Celsius, as ideal. The practical trap to remember is dressing for the coldest part of the ride, usually a fast descent or the moment rain begins, rather than the warm effort of a climb. At the hot end, the score reflects the added burden of heat and strong sun on sustained efforts.
The smartest use of the score is to plan around it rather than simply obey it. Because wind direction matters as much as speed, a classic tactic is to ride the outbound leg into the wind while you are fresh and let the tailwind carry you home when you are tired, turning a windy day's score into a manageable ride. A day that scores poorly for a long road ride might still be fine for a short spin or a sheltered route. And a genuinely low score, with strong wind and heavy rain, is a sensible cue to choose the indoor trainer or a rest day rather than heading out into conditions that are neither fun nor safe.