This appears to be an exaggeration that’s making its way around less scrupulous news sources. From https://www.euronews.com/my-europe/2023/12/30/was-oslo-paral... :

a spokesperson called the allegations “an extreme exaggeration… We cancelled, on average, between 50 and 100 departures, out of more than 4,000 daily departures, for a few days.”

The company did however admit they had a few “challenges with the range of the buses being shorter in cold weather."

"We solved this by changing the charging shifts. And also by fixing the charging infrastructure."

Ruter [the bus operating company] claims the issues have since been fixed and the fleet of electric buses continues to run as usual.

That not right at all. Norwegian news say something very different and is probably more reliable.

https://www.nrk.no/stor-oslo/kaller-inn-byrad-i-oslo-pa-grun....

Reached 1000 cancelations at the worst in a single day it seems.

They managed to resume traffic by using emergency diesel replacement buses.

Oslo can't have been surprised by the existence of cold weather. Did they not contemplate any countermeasures, like heaters at the charging location or better insulating the batteries so the heat from discharging them and then recharging through regenerative braking keeps them warmer?

Bus developers probably weren't based in Oslo

Toyota isn't based in Oslo either but they know how to make a vehicle that runs there, and the companies that don't generally don't do a lot of business there.

Electric buses in Oslo Norway (of all places) is a dictate of politics, not practicality. The people implementing the politics were likely warning about such oversights, but were rebuffed. They will gladly see it all fail, so that they may say: We told you so.

The temperature does not affect to charge stored in the batteries, right? However, you have to use the battery to heat itself as well as heat the bus (unless you got diesel heater or something for the cabin).

Batteries produce electricity through a chemical reaction. When it is colder, that reaction creates less electricity.

If you fully charge a battery, freeze it, then warm it back up, it will still be close to fully charged.

It’ll impact the usable charge because the colder temps will decrease the ability of the battery to produce high currents. Effectively setting the floor for a “useful” charge level higher. Below that useful level, current supply is too low to power whatever it is you’re powering.

It’s pretty well known (in industries that use batteries) that temperature affects the capacity of batteries.

A universal problem for all EVs in cold climates

That's one reason to not switch to EVs. But muuuh local emissions free...