What this result means
Manual weather entry works for guessing, but race week you often have a forecast. This tool fetches conditions for your start time and location, then pipes them into the lab’s pace-adjustment model.
Enter a fair-weather goal pace plus where and when you start. Review the adjusted pace alongside the raw forecast.
Marathon at 09:00 in a hot city may show higher expected temp than a dawn start — adjusted pace reflects that forecast window.
If the API lacks data, fall back to the conditions board with manual numbers.
Calculation method
Forecast from the configured weather provider for the requested time and coordinates. Pace math uses the same heat, humidity, wind, and altitude heuristics as the conditions board.
Forecasts change. Re-check closer to race day.
Microclimates, shade, and hydration strategy are not modeled.
Frequently asked questions
Where does the forecast come from?
A public weather API for the location and start time you enter. Exact provider is documented on /methodology.
What if my race location is not found?
Try a nearby city or use the conditions board with manual temperature, humidity, and wind.
Does this replace the conditions board?
No. Use this when you want forecast-driven inputs. Use the board for hypotheticals or manual what-if scenarios.
Do I need an account?
No.
How often should I refresh the forecast?
Check again within a few days of the race and the morning of if conditions look volatile. The tool uses the window you request, not live updates.