Running in the rain

The Run Score calculator requests Open-Meteo precipitation probability, precipitation amount, rain and showers as separate hourly fields. They are forecast estimates, rather than a measurement following you around the route. Check the forecast for the finish as well as the start.

An hourly total can conceal a brief, harder burst; it does not report the maximum intensity inside that hour. Keep the provider, timestamp and accumulation period attached to any rain figure; a whole-day total is a different input from an hourly total.

In Ito and colleagues’ 2013 laboratory study, seven men ran for 30 minutes at a fixed workload in 5°C air. Adding rain lowered body and skin temperatures and increased oxygen consumption. It did not measure how much slower an outdoor runner should go.

Ito and Yamashita’s 2025 study combined rain and wind in 10°C air for an hour of running in eleven men. Oxygen consumption increased, and perceived effort was higher late in the run. Because rain and wind were added together, the study cannot isolate the effect of either one.

The hot-condition result went the other way: in a 2015 study of eleven men running at a fixed workload in 33°C air, rain lowered body and skin temperatures and later heart rate. That is evidence of reduced heat strain in those conditions, rather than proof of a faster run. These small laboratory studies give context, not a rain-rate cutoff for cancelling a run.

The ACSM cold-weather consensus also treats wetness and icy terrain as additional hazards. For a cold, windy forecast, consider a shorter route with a way home and dry kit ready at the finish. This is a planning choice, not a claim that a particular jacket makes the conditions acceptable.

NWS guidance says to stop outdoor activity and get to suitable shelter immediately when a thunderstorm is in the area. If you hear thunder, see lightning or the sky looks threatening, seek shelter. A substantial building with wiring and plumbing provides protection; a hard-topped metal vehicle with its windows closed is another option.

A tree, tent or open rain shelter does not provide the protection of that building or vehicle. Once inside a building, stay away from windows, doors, plumbing, wiring and connected equipment. NWS recommends waiting at least 30 minutes after the last thunder before resuming outdoor activity. Every new thunder restarts that wait.

Check storm warnings and shelter access before leaving. A route with no reachable suitable shelter needs a different plan when thunderstorms are forecast, such as moving the run indoors or postponing it. A favorable comfort score cannot overrule thunder you hear.

NWS guidance is clear: never walk into flood water. Turn back from a flooded path, underpass or crossing, and follow closures rather than going around a barrier. A rain amount in an app does not tell you the depth, current or condition of the surface underneath.

For ordinary rain without a storm or flood warning, practical options include a route away from traffic, daylight, and kit that makes you easier to see. These are choices to consider, not guarantees that a driver has seen you. If you cannot see crossings and the surface clearly, stop somewhere suitable and change the plan.

If you wear prescription glasses, a brimmed cap and a lens treatment approved for your lenses are options to test before a longer wet run. Neither comes with an anti-fog guarantee here. Carry a suitable cloth if that helps your setup, and stop to clear your view rather than trying to adjust glasses while running through a crossing.

Keep the shoes and socks you have already tried on your route. Inspect the surface and take particular care at turns and descents; shoe tread alone cannot certify grip on wet or icy ground. Avoid a pace target that requires you to keep running when you cannot judge the footing.

Consider a rain layer for cold or windy conditions, then test how it feels at your usual easy effort. Clothing, seams and anything you use for chafing should be familiar. This page does not rate fabrics or claim that any product prevents rubbing.

Before leaving, decide where dry clothes will be and how you will get back if you shorten the run. A waterproof bag for a phone or spare kit is an option to test. At the finish, have somewhere sheltered to change out of wet clothing rather than leaving that decision until you stop.

Before the start: check the organiser’s weather instructions, bag-drop access and where you can wait. Decide which layer you want while waiting and where it will go before you run. These are practical planning choices for the venue you have.

While running: follow event instructions, check visibility and footing, and know where to stop if conditions change. Thunder and flooded crossings still require the shelter and flood decisions described above.

After the finish: arrange dry clothes at the collection point and a way home. Check the forecast for waiting and the journey as well as the run. Follow the organiser’s plan if weather requires a delay, cancellation or route change.

The shared RunWeather pace model includes a rain term that responds to amount, weather code, temperature and wind. That output is a model estimate. The studies above do not validate a fixed percentage slowdown for every rainy run, and this guide does not prescribe one.

The app suppresses exact pace advice when its safety assessment flags an active thunderstorm or icy ground. Those rules depend on the forecast inputs. A pace number that remains visible cannot confirm that the local path is clear, that the rain will stay light, or that no storm is approaching.

If local conditions allow you to run, leave room to change the route, duration and effort as they develop. If another hour fits the run better, move it. You do not need to turn a wet forecast into an argument for finishing the original plan.