What shipped this summer

A lot has landed since launch. This is the short version of what changed, why, and what it means if you use WetBulbTracker regularly.

Paw and pavement safety

The biggest addition is a model of the ground, not just the air. Asphalt in full sun runs 40–60 °F hotter than the air around it, which is why a walk that feels fine to you can burn a dog's paws.

A paw check on the reading card and on every city page, estimating the actual surface temperature and grading it against burn thresholds.
A pavement layer on the map, so you can see surface heat across a whole area rather than at one point.
A shareable paw card at /paws for sending to another dog owner.

The part we're most pleased with is what happens after dark. A simple steady-state model concludes that once the sun is down the ground is at about air temperature — which is comfortable, wrong, and wrong in the dangerous direction, because it under-warns exactly during the evening dog-walking window. Our surface model is transient: it integrates roughly a day of recent weather, so the ground at 9 p.m. still carries the sun that fell on it at 3 p.m. Full write-up: why pavement stays hot after sunset.

Accuracy work

A conditions-based bias correction learned from live comparisons against the U.S. National Weather Service. It's not a single global offset — the correction varies with solar radiation and wind, because that's where the error actually lives. Cross-validated on cities it never trained on, it cuts error by about 31%.
The live accuracy dashboard at /validation shows the comparison in public, including where we run warm or cool.
Details: how accurate is this WBGT.

Reading the number

At a glance now gives you the two best windows and the peak to avoid, per day, rather than a wall of hourly values.
Activity guidance covers general activity, outdoor work, athletics and tactical training, and now states whose standard each one comes from instead of burying every source in one line of fine print.
Where our athletic guidance and a state high-school policy differ, the page now explains why rather than showing two contradictory instructions: ours is a general screening recommendation, the state policy is the rule your school is actually held to.
Guidance is night-aware — it no longer suggests finding shade at 2 a.m.

Personalization

All the personal factors — exertion, heat adaptation, age, health sensitivities — now live in one "Adjust for your situation" card, with a reset. Your risk and the activity guidance both react to it live, and your risk explains why it differs from the general reading. Personalization only ever escalates guidance; it never relaxes it below the objective number.

Everything else

Custom reports open over the map instead of navigating away, and the map keeps your view — location, zoom, forecast hour, layers — when you leave and come back.
Search is location-aware: typing a few letters surfaces places near you rather than a village on another continent.
City pages now say how fresh their reading is rather than claiming "right now", and carry the full guidance and paw check so you don't have to leave.
New explainers in Learn, including is it too hot to walk my dog and why 87 °F can beat 105 °F.

As always the methodology documents every formula, constant and assumption — now with a searchable table of contents, because it's grown to eighteen sections.