Methodology
How the sentence gets made, and where it can be wrong.
The short version
Every sentence on the page is picked by a rule that reads a number. A dry day cannot say "rain", because the words are chosen by the forecast and not written in advance. The jokes are kept apart from the facts and matched to the weather by the same kind of rule, so a rain pun cannot show up on a dry day.
Where the data comes from
| Source | What we use it for |
|---|---|
| National Weather Service | In the United States: the hourly forecast, the latest observation, official alerts and the nearest radar. It is the official word, so it leads. |
| Open-Meteo | The past few hours, UV, pressure, gusts, rainfall amounts, sunrise and sunset, the 15-minute rain outlook (United States and Canada), place search, and the whole forecast outside the United States. Weather data by Open-Meteo.com, under CC BY 4.0. |
| AirNow | The air quality index, United States only. |
| The Lumber Outlet Group shop | The one product suggestion, read from the shop's own catalog each time. |
Your browser talks only to this site. We ask the weather services on your behalf and keep each answer for a few minutes, by one-kilometre grid cell: forecasts 10 minutes, alerts 5, air quality 30. If a source is down, we keep showing its last good answer (up to three hours for forecasts, half an hour for alerts) and the page says "Some data is late".
Feels like
We work out "feels like" ourselves, the way the Weather Service does: wind chill at or below 50°F with wind above 3 mph, heat index at or above 80°F and 40 percent humidity, and the plain air temperature otherwise. Doing it ourselves means the number does not jump when one source takes over from another.
What counts as rain
An hour counts as wet when the forecast says rain, drizzle, snow or storms and the chance is at least 40 percent or the expected amount is at least half a millimetre (0.02 inch). If the sky word says cloudy, it takes a 60 percent chance and at least 0.3 millimetre. A forecaster hedging at 20 percent is not rain, so we do not call it rain.
In the United States and Canada the next two hours use a 15-minute outlook. Elsewhere the page shows the hourly chance and says so.
Confidence
Where both the Weather Service and Open-Meteo cover your place, we compare their temperatures hour by hour for the next 12 hours. If they average within 1°C (about 2°F) of each other, we say High confidence. Within 2.2°C (about 4°F), Medium. Further apart, Low, and the "why" box says to take the forecast loosely. This is a check on agreement between two forecasts. It is not a probability.
The lenses
- Everyday. How it will feel over the next six hours, then the next rain.
- Run and ride. Scores every hour in the next day or so on how it feels (best between about 45 and 58°F), rain, thunder, wind, dew point, daylight, time of night and air quality, and names the best one. If nothing scores well, it says treadmill day and why.
- Commute. Looks at 7:30 AM and 5:15 PM: rain at those hours and just before, and ice when it is near freezing with moisture around.
- Hunt and fish. Pressure, light, and plain storm warnings. Talk about fish and game moving with the barometer is labelled as folklore, because it is. Shooting hours are set by your state, not by us.
- Home and yard. Freezes, mowing windows, and whether it rained enough to skip the sprinklers.
- Build and finish. Stain and finish windows from dry stretches and the moisture a board settles to in the air, worked out from temperature and humidity with the Hailwood-Horrobin equation as printed in the USDA Wood Handbook.
Official alerts
Alerts come from the Weather Service as written. We show the event, when it ends, what to do and what is happening, and we do not reword them. Every warning and emergency, and anything the Weather Service rates severe or extreme, turns the jokes off, along with the shop suggestions and the shirts. When the Weather Service marks a warning as immediate, like a tornado or flash flood warning, it also becomes the headline and the details open by themselves.
Where it can be wrong
- A forecast is a forecast. The page says "around 1 PM" because that is the honest size of the claim.
- Outside the United States there are no official alerts on this page yet. It says so. For warnings, check your own country's weather service.
- Rain in the next two hours is a model's estimate, not a live radar reading. The radar loop is the Weather Service's own picture, United States only.
- Place search finds cities, towns and postal codes, not street addresses.
- The shop suggestion and the shirts are about as scientific as a pun.
If you find something wrong, tell us: help@thelumberoutletgroup.com.