Heat and cold embargoes: the reason a booked flight gets cancelled

Last verified: 2026-08-25

The answer

Airlines will not carry animals outside a temperature range, and the temperature that counts is on the ground — at departure, at every stop, and on arrival — not in the cargo hold in flight.

One carrier’s published band, authoritative for that carrier only:

Delta does not ship pets when the temperature exceeds 80°F (27°C) or falls below 20°F (−7°C) during ground time. A Certificate of Acclimation is required for temperatures between 20°F and 45°F.

Every stop on the itinerary has to be inside the band, on the day. A Melbourne summer arrival and a northern-hemisphere summer departure can both breach it, at opposite ends of the same flight.

Why this is worse than it sounds

An embargo is not a rule you satisfy months in advance. It is assessed close to departure, sometimes on the day — after the microchip, the titre test, the 180 days, the permit, the quarantine booking and the parasite treatments are all done and dated.

And your dates are not freely movable. The import permit is valid only until the RNATT expires, and the animal must arrive before the permit expires. So a weather cancellation does not just delay the flight; it spends part of a window that cannot be extended without repeating the whole RNATT process.

Planning around it

1. Choose the season deliberately. Australia’s summer is the northern hemisphere’s winter — one end of your route is likely to be at a temperature extreme whenever you fly. The shoulder months are the least contested.
2. Count your permit window. Know your last possible arrival date, and do not plan to use the final days of it.
3. Fewer stops means fewer thermometers. Each ground segment is another place an embargo can apply.
4. Ask the carrier for its band in writing, including whether a Certificate of Acclimation is accepted and who signs it.
5. Book early enough to rebook. One carrier will not take a cargo pet booking more than 14 days before departure, which is short notice for a plan six months in the making — ask yours what its window is.

What this page does not tell you

• Any carrier’s embargo other than the Delta example above, read on 26 August 2026.
• Whether a Certificate of Acclimation is accepted for travel to Australia, or who may issue one.
• Historical temperature data for any airport.