**Popcorn pops when the kernel reaches about 180°C (356°F)**, typically within a range of roughly 177–187°C. Water trapped inside builds pressure until the hull ruptures; the sudden release lets the softened starch expand into popcorn. In one experiment using an oven, 34% of kernels popped at 170°C, compared with 96% at 180°C. [Popping-temperature study](https://pmc.ncbi.nlm.nih.gov/articles/PMC4345489/)

**Yes, a 250°C oven is hot enough.** The important distinction is between the oven temperature and the temperature inside the kernel: the kernel takes time to heat up, and it should pop well before reaching 250°C.

A covered roasting pan can therefore work, but I would expect it to be less convenient and less consistent than a saucepan on the hob. In an oven, the popped corn remains exposed to heat while you wait for the remaining kernels, and it is harder to shake the pan or stop heating promptly. At 250°C, that gives you less margin before scorching. This is a practical inference from the heating method, rather than a result established by the temperature experiment.

If you want to try it:

- Preheat the oven to **about 190–200°C** as a starting point.
- Use a small batch of plain popcorn kernels in a single layer in an oven-safe metal pan, with plenty of room for expansion.
- Cover with an oven-safe lid that contains the popcorn but allows steam to escape.
- Listen closely and remove the pan when popping becomes infrequent; avoid waiting indefinitely for every kernel.

That is an experimental starting point, not a tested roasting-pan recipe. For reliably good popcorn, I’d use a covered saucepan with a little oil: it transfers heat efficiently and lets you shake the kernels and remove the pan quickly when popping slows. The Popcorn Board gives instructions for that method. [Stovetop popcorn instructions](https://www.popcorn.org/Recipes/Preparing-Perfect-Popcorn)