# Outdoor Job Weather Window

> Find the best hours this week to paint, mow, barbecue or walk, by clear weather rules. Checks the MET Norway forecast hour by hour against the rules of an outdoor job — temperature, humidity, wind, rain and dew point — and lists every window long enough to do it, including rain-free time afterwards for paint to cure or before mowing for the grass to dry.

Part of usefulweb.app (https://usefulweb.app/). Part of [Hearth](https://hearth.usefulweb.app/) (ownerApp: hearth). Results are deterministic calculations from the inputs and the listed assumptions; the API returns exactly what the web page shows.

## Use it
- Human interface: https://hearthweatherwindow.usefulweb.app/ (interactive tool at https://hearthweatherwindow.usefulweb.app/tool)
- JSON API: POST https://hearthweatherwindow.usefulweb.app/api/v1/calculate with a JSON object of inputs (schema: https://hearthweatherwindow.usefulweb.app/api/v1/tool)
- OpenAPI: https://hearthweatherwindow.usefulweb.app/openapi.json
- MCP (Streamable HTTP): https://hearthweatherwindow.usefulweb.app/mcp - tool `hearth_weather_window`

## Inputs
- place (text, required): Place (latitude, longitude) - Decimal degrees such as “52.52, 13.40”, or degrees-minutes-seconds. Rounded to 0.01° (about 1 km) before the request.
- timeZone (text): Time zone of the place - IANA name such as Europe/Berlin, Europe/London or America/New_York. Hours and dates are shown in this zone.
- activity (select): Activity
- days (integer): Days ahead - MET Norway forecasts about nine days ahead: hourly for the first two to three days, then in 6-hour steps.
- minTemp (number): Lowest temperature (°C, optional) - Empty = the activity’s rule (painting 10, mowing 5, barbecue 14, walk −5).
- maxTemp (number): Highest temperature (°C, optional)
- maxHumidity (number): Highest relative humidity (%, optional)
- maxWind (number): Strongest wind (m/s, optional)
- minHours (integer): Hours needed (optional)

## Method
- Fetches the MET Norway Locationforecast 2.0 for the place (rounded to 0.01°, cached until MET’s Expires time) and builds an hourly series; 6-hour steps after the first days are split into hours with interpolated values.
- Each hour inside the activity’s day hours is checked: no rain (≥ 0.1 mm per hour, ≥ 0.2 mm per 6-hour step or a rain chance ≥ 40 % count as rain), temperature, relative humidity and wind within the limits and, for painting, the air at least 3 K above the dew point (ISO 8502-4 asks this of the surface; air temperature stands in for it).
- Presets: painting 10–30 °C, ≤ 85 % humidity, ≤ 7 m/s, 4 hours plus 4 rain-free hours afterwards, 8:00–18:00; mowing 5–30 °C, ≤ 90 %, 2 hours with 3 dry hours before, 9:00–20:00; barbecue 14–32 °C, ≤ 8 m/s, 3 hours, 11:00–22:00; walk −5 to 28 °C, ≤ 10 m/s, 2 hours, 7:00–21:00. Your numbers replace the preset values.
- Runs of suitable hours are trimmed until the rain-free buffers hold and kept when they are at least the hours needed. The best window is the longest (earliest on a tie); the blocker count shows which rule failed most often.

## Limits
- A forecast window is a plan, not a promise: check the latest forecast and the paint maker’s instructions before you start.