Well, that seems unrealistic for metals, but every
conductor does have -some- temperature dependence.
Maybe somebody is "helping" you worst-case stuff. It
might be worth your while to find where the tempco
info resides, check against a verifiable data source,
and correct it.
I dont really know what your end result is, but if you can dissipate energy as heat then Nickle coils gain good resistance as they get warmer. I might have the resistance temp coefficient somewhere if that's a solution you can use?
Nickle has high temperature coefficient of resistance but it is not a good conductor, Silver or copper is good conductor(Low resistivity)
You can use the word resistance instead of impedance. because impedance is applicable if resistance, inductance and capacitance element are involved.
If your conductor is a small straight wire, inductance and capacitance are negligible. Otherwise capacitance and inductance of an air coil would not vary with temperature. Resistance only will vary with temperature.