A lot? e.g. Chicago gets it every year
>> > What percentage of the (US) population gets temperatures like that? That's generally mostly IECC Zone 7 (though cold snaps in Zone 6) can happen:
> A lot? e.g. Chicago gets it every year
[citation needed]
Per historical weather data:
https://ashrae-meteo.info/v2.0/index.php?lat=41.960&lng=-87....
It is warmer than -16C/3F at Chicago (O'Hare) for 99% of the time (i.e., except for 4 days a year), and warmer than -18.7C/-2F for 99.6% of the time (2 days).
ASHRAE are the folks that publish the heating/cooling standards that are used in building codes for estimate heating/cooling equipment capacities (Manual J) and selecting the right equipment (Manual S).
Here's a PDF with a lot of locations in the US and CA (and other countries further down), and if you look under the "Heating DB" column, you'll find very few US locations that have -30F under the 99% (or even 99.6%) sub-columns:
* https://www.captiveaire.com/catalogcontent/fans/sup_mpu/doc/...
So unless you're in AK, MN, or ND, long runs of temperatures colder than -20F/-30C don't happen too often. Of course if you have a leaky house with little insulation, you're throwing money out the window/door, so the first consideration for a good ROI is better air sealing and insulation.
Also..
> It is warmer than -16C/3F at Chicago (O'Hare) for 99% of the time (i.e., except for 4 days a year), and warmer than -18.7C/-2F for 99.6% of the time (2 days).
If my heat doesn't work for those days, I'm kind of boned. Four days per year without a working heat pump? That's a mess.
Which is, of course, very expensive to use -- but it's only expensive for those 4 days. Resistive heat can be avoided for the other 361.2425 days in a year.
In the US (as of August of 2025), the average price of residential electricity per delivered kWh is $0.1762 [1].
If using resistive heat averages 4kW during each of those 4 days (it's probably either more than that, or less than that, but ballparks are ballparks), then that's about $16.92 for each of those days. Or: $67.66, per year.
Not so bad, right? Or at least, not "boned."
[1]: https://www.eia.gov/electricity/monthly/epm_table_grapher.ph...
