How rain becomes river level
Two different clocks run at once. A downpour can put a short pulse through a gauge in days; the slow store that holds a river up through a dry summer moves over weeks. They are not the same process, and no single number joins them.
The sequence
- Where and how hard it rains. Rain over the headwaters behaves differently from the same rain over the lower river.
- What the ground does with it. Dry soil absorbs a first storm almost entirely. Saturated soil passes nearly all of it on.
- How the tributaries route it. Each arrives on its own schedule, so one storm can reach a gauge as several small rises rather than one.
- What appears at the gauge. A pulse: a rise, a peak, and a recession over days.
- What is left afterwards. The slow store that holds the baseflow up, which moves over weeks, not hours.
What we will not tell you
- No millimetres-to-centimetres conversion. We do not publish a coefficient that turns forecast rain into a gauge reading, because the honest version of that number depends on soil wetness, snow, tributary timing, reservoirs and lock operations — all of which vary between two storms of identical size.
- Rain never moves a clear-line. The gap you see for a corridor is today's measurement against today's arithmetic. A wet forecast does not change it.
- No rain-derived probability. Forecast precipitation is not converted into any statement about your sailing.
- No climate-model projections. A 14-day weather forecast is a short-range operational product and is kept visually and computationally separate from everything else on this site. Nothing here is a multi-decadal projection.
Rain in the next 14 days
Rhine above Kaub — representative catchment precipitation.
3 days: 0.0 mm · 7 days: 0.1 mm · 14 days: 0.1 mm — forecast precipitation.
Rain forecast by Open-Meteo (commercial licence), model icon_seamless · fetched 21 September 2026 at 02:39 UTC · covering 14 days, 21 September to 4 October.
Weather data by Open-Meteo (commercial licence) · Representative catchment precipitation total from 8 weighted sampling points; a point sample, not an areal mean.
Rain may slow a fall or create a rise after losses and routing. Waterlogged does not convert this forecast into gauge centimetres or a cruise-disruption probability.
Read a rain forecast at the source
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Deutscher Wetterdienst — official German weather forecasts
Germany's national weather service forecast for the Rhine, Main, Moselle and Danube catchments.
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yr.no — free European rain forecasts (MET Norway / NRK)
A free public forecast covering the same catchments, if you want rain amounts today.
For an authoritative river-level forecast, read the authority's own product — linked from every gauge page and from the corridor board.