How we know

Reports and stages

A report says what one place looked like on one day: its stage, and a share turned or in bloom only when a source gives one. Every report lists at least one source.

A place page shows its latest report as the current status for 45 days. After that the page says there is no current report, and the picture shows the place's typical peak look, labeled as such. Spots inside a place (a pass, a park, a garden) have their own reports.

Each event has its own stages, first to last. Where the peak stage has another name, it's marked “peak”.

• Texas bluebonnetsRosettes→First blooms→Filling in→Peak carpet→Going to seed
• Cherry blossomsGreen buds→Florets visible→Extension of florets→Peduncle elongation→Puffy white→Peak bloom
• Fall foliageStill green→First color→Moderate→High color→Peak→Past peak
• Synchronous firefliesBeginning→Peak→Declining
• LavenderGreen→First color→Full bloom · peak→Harvest
• Desert superbloomNo bloom yet→Early bloom→Good bloom→Superbloom · peak→FadingBefore the season, forecasts may also rate it as a whole: Poor, Fair, Good, Superbloom possible.
• TulipsGreen shoots→First color→Fields blooming→Peak color→Fields topped
• WildflowersNot yet→Early→Good→Peak→Fading

Forecasts

• Every forecast shows the day it was issued and its sources.
• High confidence: an official forecast, or two or more sources that agree. Medium: one source, or our own model. Low: only the average of past years.
• A forecast stays on its page until 30 days after its window ends, then gives way to the next one.
• Before there is a forecast, a page shows the place's typical window from past years, labeled “Typical timing, not a forecast yet”. We never show last year's dates as this year's.
• We never invent a date, a percentage, a quote or a source. If we don't know, the page says so.

Where the information comes from

We use only information that is free to reuse: US federal government works (the National Park Service, the Forest Service, NOAA and the National Weather Service, the US Geological Survey, the Census Bureau), openly licensed data such as the USA National Phenology Network's, and sites whose terms say in so many words that their content may be reused. Everything is written in our own words, with a link.

Each place page lists its sources under “How we know”, newest first, with the day we read them and a link.

• Official report: Official reports, such as the National Park Service's bloom updates.
• Park Service: National and state park updates, such as the National Park Service's bloom stages.
• Satellite: Satellite imagery of how green or colored the land is.
• Phenology model: Models of when plants leaf out, bloom and turn, built from years of observations.
• Sightings: Dated observations from people on the ground.
• Weather: Forecasts of frost, heat, wind and rain that move a peak earlier or later.
• Our forecast: Our own forecast, built from the sources above and always listed with them.
• Reference: Background data a page is built on, such as the Census Bureau's state population centers.

The live map

Each state takes the most advanced report among its places from the 14 days up to that week, so the map only shows fresh reports. Weeks ahead show forecasts only, outlined with a dashed line. States without a report stay plain. See the live map.

Typical windows and the year calendar

A typical window is when a place usually peaks, from past seasons and with its sources. The year calendar and the “When it usually peaks” charts use them. Places whose timing we haven't researched yet aren't placed on either.

Pictures

The landscapes at the top of each page are illustrations, drawn for each place in the colors of its current stage. Some pages also show a few photos from federal collections (the National Park Service and the Fish and Wildlife Service) whose own pages mark them public domain. They're illustrations too, never this week's view: each names where it was really taken and who took it.