The Wet Season: Three Distinct Problems

"Wet" isn't one condition. It's three, and they fail your grip in different ways.

Steady rain on sound tarmac — f ≈ 0.4, braking doubled. This is the wet column of the stopping table: honest, planable, and bad enough. 50 km/h stops in about 46 m instead of 34; 100 km/h needs about 142 m.

The first rain after a dry spell — briefly worse than steady rain. Weeks of dry weather let engine oil, diesel spill, rubber dust and fine dirt build up on the tarmac. The first shower doesn't wash this away — it emulsifies it into a lubricant film. For the first stretch of the first rains, the road behaves closer to f ≈ 0.25–0.3 than the steady-rain 0.4: braking distances toward triple dry, on a road that only looks damp. The film washes off with sustained rain; the danger window is roughly the first hour on each stretch. Treat the season's first shower as the year's most slippery tarmac — it sounds like hadithi za kale but it's plain surface chemistry.

Standing water — a different failure entirely. Above a threshold speed, your tyres stop cutting through the water to the road and ride up on top of it: aquaplaning. Friction drops effectively to zero — no braking or steering transmitted at all. Recognition and recovery belong to the Adverse Conditions module; the point here is that the friction ladder has a floor below ice, and deep-enough water at speed reaches it.