Name the crossing, not the county.

When a storm starts in Juja, riders get “more than 80 mm in some areas”. Crossing Watch turns one rain gauge into a call for each named crossing: cross, wait or reroute, and for how long.

Watch the 20 March replayOpen the rider app

Runs on the JKUAT weather station’s real 15-minute rain data, 6–24 March 2026.

Friday 20 March, 17:15. The rain hits JKUAT.

51 mm fell in under three hours, 12 mm of it in fifteen minutes. Each row below is the call one crossing would have given a rider, every fifteen minutes, on the real gauge data.

Kimbo–Matangi goes red at 18:00
“Likely flooded for two and a half hours. Use Kenyatta Road.” At 20:30, right on time, the call eases to wait; by 21:15 it’s cross.
The campus culvert drains first
JKUAT’s Technology Street clears an hour before Kimbo–Matangi, on the same rain.
The river is slow
The Ndarugu bridge rises last and stays up past midnight, long after the rain stops at 20:15.

Three things make the call.

  1. 52 / 52 mm

    One gauge, every 15 minutes.

    The JKUAT station's running daily total, read carefully: its raw rain column under-reports about 17×, and its second gauge follows the sun, so we set it aside.

  2. JKUAT
    Kimbo–Matangi
    Ndarugu

    A bucket for every crossing.

    Rain fills it and it drains at the crossing's own speed: 45 minutes for a campus culvert, ten hours for a river bridge. Same storm, different signatures.

  3. before
    after one report

    Riders set the trigger.

    A "flooded" tap at a known water level cuts the range where the trigger can be. One report at the Ndarugu bridge narrows it 45%.

The full method, with a trigger you can train yourself 

What we know, and what we don’t yet.

Real

  • Rain: the JKUAT station's own readings, 6–24 March 2026.
  • Kimbo–Matangi flooded after the March rain (The Star, 9 Mar 2026). That report sets its trigger.
  • Rivers, roads and detours: OpenStreetMap, routed at boda speed.
  • A storm it never saw: trained on March only, it called Kimbo–Matangi red at 23:00 on 27 April. The Star photographed the road flooded the next day.

Not yet

  • Triggers start from a single storm. Wide, dashed bands on screen say so, and every tap narrows them.
  • The flooded spot on Kimbo–Matangi comes from residents' posts, and the detour is the shortest dry route on OpenStreetMap. Riders still need to confirm both.
  • Drain times are rough. After that April storm it said cross at 04:15, but the road stayed flooded through 28 April.
  • No rider survey yet. The Kiswahili copy needs a native speaker's review.

Ready before the October rains.

Kenya Met expects wetter-than-normal rain in Kiambu from the second and third weeks of October. A pilot needs three boda stages, JKUAT, one gauge and riders willing to tap.

Watch the replay Open the rider app