How it works

What a verdict means

GoNoGo applies its own activity-specific scoring rules to an hourly weather forecast. It does not issue official weather warnings or determine whether an outing is safe, legal or suitable for a particular person or item of equipment.

A score of 70–100 is GO, 45–69 MAYBE, and 0–44 NO-GO. A MAYBE cap limits the effective score to 64, and a NO-GO cap to 40. These are the app’s suitability bands, not certified safe operating limits.

How the number is calculated

Each scorer starts at 100, subtracts condition penalties and clamps the result to 0–100. Critical-condition caps are then applied. The same effective score is used for the verdict colour and displayed number. A high raw score cannot override a cap.

Missing inputs can make an existing widget’s score incomplete: the underlying model does not estimate missing factors. Never interpret an unavailable metric as favourable. The country comparison withholds its verdict unless all eight required inputs are present.

Inspect all nine activity models

• Motorcycle
• Cycling
• Drone & RC
• Hiking
• Running
• Fishing
• Kitesurfing
• Sailing
• Golf

How to read the examples

Each example changes only the listed inputs from a dry, clear reference hour: air and feels-like temperature 18°C, steady wind and gusts 10 km/h, visibility 10 km, no precipitation, 0% precipitation probability and UV 0. These illustrative results are calculated from the same scoring functions as the live tool. Several penalties can combine into a lower verdict.

The best-window and daily summaries

The main activity widget searches the available week for a run of at least two daytime hours (06:00–21:00 start times), using effective scores. It maximises the average score plus a small duration bonus of 1.2 points per hour, capped at six hours. This is the best available period, not necessarily a GO period. A day’s summary is the average of its four best daytime hourly scores, so it can look favourable while other hours are poor.

The country comparison answers a different question: the earliest pair of consecutive, complete GO hours whose start times fall in the next 24 hours. It includes night hours, which are labelled in local time; it does not establish daylight suitability. If none is found, it says so. Neither summary covers your whole outing automatically.

Forecast sources, coordinates and time

Open-Meteo’s forecast API supplies numerical weather-model forecasts, not observations made by this site. Model selection and resolution vary by location. A requested city coordinate represents a forecast point, not the whole country, route or flying area. The API may use a nearby model grid cell. The widgets display time for the forecast location; country cards label their own timezone.

Forecasts are retrieved on page use. A retrieval time is not the weather model’s issue time. Near-term forecasts can still miss local showers, shelter and terrain effects. The model does not ingest official alerts, marine conditions or road/trail status. Check the appropriate local sources separately.

Editorial ownership and corrections

GoNoGo Weather is an independent weather project. The verdicts are automatically calculated; the thresholds are product settings, not a published safety standard or an expert certification. This explanation and the worked examples were checked against the production scoring functions on 14 September 2026. No field-testing claim is made. To report a mismatch, include the activity, location, time and displayed inputs via Contact.