Curfew

19 of 19 centres with published closing hours shut their doors while the surrounding block was still above 30°C (86°F). Harmon Library closed at 18:00 into a block that never cooled: 12 straight hours of measured heat with the doors shut.

When a night never falls below 27°C (80°F), a body without air conditioning cannot shed the day's heat strain and starts the next day depleted; that is who a cooling centre's last open hour is for. Yet closing hours are set by schedule, not by temperature. New York's comptroller found only 11% of that city's centres kept any evening hours at all, and until now no tool could say, block by block, what one more closed hour costs. This page is that measurement.

Measured, not modeled. 31 live API calls against the FortyGuard Temperature API for this night: 2m air temperature on 100 m tiles, sampled hourly through the night. Site locations and closing hours come from the live MAG Heat Relief Network registry.

33hot or never cooledWhere the doors are

Every centre in the network, drawn as a column: its height is the hours the surrounding block stayed at or above the danger threshold after the doors closed. The dashed box is the area sampled hourly; flat discs outside it were checked only for their night minimum. Drag to orbit, scroll to zoom, click a column for the centre's night.

12hlongest waitDoors close, heat stays

Each row is one centre's night, 18:00 to 06:00⁺¹ the next morning. The number on the right is the hours its block stayed at or above 30°C (86°F) after the doors shut. On this night the red runs to the edge of the chart on every row: no block cooled before the measurement window ended at 06:00⁺¹.

31.9°coldest, all nightHow the night actually cooled

One line per centre's block, late afternoon to the following dawn. On this night no curve ever reaches the dashed threshold line, so there is not one crossing dot to draw. Harmon Library is drawn in red; click any column on the map above to follow a different centre.

22hourly sitesEvery centre in the hourly box

The 22 swept centres are listed further down; they have a night low but no hour, so they cannot be ranked here. Any column heading sorts. ⁺¹ marks an hour after midnight: 01:15⁺¹ is 1:15 the following morning. “Stay open until” is the hour this night's measurement supports: the moment the block fell below 30°C (86°F), or dawn when it never did. “Hours exposed” is how long the block stayed above the threshold after the doors closed; night low is the coldest it got.

1.84°peak spreadThe threshold has to land after midnight

Cross-site temperature spread by hour, averaged over the validation nights. The metro is nearly uniform during the evening cooling ramp and separates after midnight, peaking at 02:00 with 1.84°C between blocks. A threshold crossed at 23:00 reads a city that looks the same everywhere; one crossed after midnight, like 30°C (86°F), reads real block-level separation.

7measured nightsDoes the ranking hold from night to night?

If which centre cools last were a fixed property of the place, one report could set hours for the whole season. Across 7 measured nights it does not settle: 4 of them produced no ranking at all, because no block cooled before dawn, and the 3 night pairs that remain range from -0.04 to +0.95.

mean rank correlation between nights

+0.35Kendall tau; +1 would be a stable ranking, 0 is shuffle

median swing in a centre's rank

8places between its highest and lowest ranked night

mixed: some night pairs reproduce and others are near shuffle, so a ranking is advisory for its own night only

So Curfew is a nightly call, not a seasonal schedule: the magnitudes reproduce, the ordering only sometimes does, and the honest product is this page regenerated every night.

22/22never cooledThe rest of the network

22 centres sit outside the hourly box and were swept instead: two ranged calls per box give every block its coldest hour of the night. That answers whether a block recovered at all, but not when, so these sites carry no hour and no rank.

22 of 22 swept blocks never fell below 30°C (86°F) at any point overnight; 0 did.

• Ironwood Library34.7°
• Streets of Destiny Global Outreach Center34.2°
• South Mountain Community Library34.0°
• Cesar Chavez Library33.9°
• Century Library33.9°
• Phoenix Maryvale Corps33.8°
• Valle del Sol - Indian School33.8°
• Saguaro Library33.7°
• Desert Sage Library33.7°
• Iglesia Apostólica de la Comunidad33.6°
• Palo Verde Library33.6°
• MIND24-733.6°
• Cholla Library33.6°
• Yucca Library33.6°
• Family Heat Center at Trinity United Methodist Church33.6°
• Valle del Sol - Maryvale33.5°
• Juniper Library33.3°
• Acacia Library33.3°
• Agave Library33.2°
• Mesquite Library32.8°
• Desert Broom Library32.0°
• North Valley Regional Library31.9°

What this is not

It is not a heat map. Every comparable tool ranks places; an operator has already chosen the place. What they set is an hour. It is decision support for an agency, not medical advice, and it does not predict health outcomes.

On the night of August 18, 2026, every centre with a closing time in this network shut its doors onto a block that stayed above 30°C (86°F) until dawn. The hour on the door is the one variable an operator controls; this page prices it, per site, per night.