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 days it never trained on, it cut error by 34.3% on the 9 September 2026 reading; the current figure is on /validation.
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.

A page for how you actually use it

Heat means different things to a foreman, a coach, a first responder and someone walking a dog — so each now has its own page. Search a place, get that audience's reading and guidance, and share the result, without going through the app at all:

Outdoor work — work/rest guidance for crews and safety officers.
Athletics — practice and competition, shown alongside your state's own high-school WBGT policy, with an explanation of why the two can differ and which one binds you.
Tactical — flag conditions for military and first-responder training.
Paw safety — the ground temperature, not the air.

Share one and whoever opens it lands on the same reading you were looking at.

The map shows time properly

Day and night shading. The night side is shaded and the terminator moves as you scrub, so you can see where the sun has set — and understand that a hot reading after dark is heat the ground is still giving back.
Animation. Play the next 48 hours forward, and grab the scrubber to stop on the exact hour you care about. It's labelled with that place's own clock, not yours, because the question is whether it's their afternoon peak.

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.

Paw and pavement safety

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.

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 days it never trained on, it cut error by 34.3% on the 9 September 2026 reading; the current figure is on /validation.

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

A page for how you actually use it

Outdoor work — work/rest guidance for crews and safety officers.

Athletics — practice and competition, shown alongside your state's own high-school WBGT policy, with an explanation of why the two can differ and which one binds you.

Tactical — flag conditions for military and first-responder training.

Paw safety — the ground temperature, not the air.

Share one and whoever opens it lands on the same reading you were looking at.

The map shows time properly

Day and night shading. The night side is shaded and the terminator moves as you scrub, so you can see where the sun has set — and understand that a hot reading after dark is heat the ground is still giving back.

Animation. Play the next 48 hours forward, and grab the scrubber to stop on the exact hour you care about. It's labelled with that place's own clock, not yours, because the question is whether it's their afternoon peak.

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.