***Answer Updated 21 Jan 2022***

> To understand temperature effects, we need to look at the atomic
> structure of the elements that make up the magnet. Temperature affects
> magnetism by either strengthening or weakening a magnet’s attractive
> force. A magnet subjected to heat experiences a reduction in its
> magnetic field as the particles within the magnet are moving at an
> increasingly faster and more sporadic rate. This jumbling confuses and
> misaligns the magnetic domains, causing the magnetism to decrease. 
> Conversely, when the same magnet is exposed to low temperatures, its
> magnetic property is enhanced and the strength increases.


 [source][1]

**Similar regarding this question about relation of magnetic field generated on an electric current carrying conductor wire for example, with temperature:** 

Increase of entropy (i.e. temperature) leads to partial misalignment of the discrete magnetic moments of the uniform directional flowing electron's current and therefore to a reduction of the generated corresponding magnetic field.

In theory, a conductor wire with higher [resistivity][2] $ρ$ will generate the same magnetic field strength $B$ around it with distance $r$, with a lower resistivity wire as long as both have the same current value $I$:

**Magnetic field around wire**

$$\mathrm{B}=\frac{\mu_{0} \mathrm{I}}{2 \pi \mathrm{r}}$$


However in a higher resistivity wire the atoms inside will scatter more electrons of the current and generate more heat (i.e. increase of entropy of current's uniform flow) therefore the number of electrons passing through the cross-section of the wire per unit of time will decrease thus also the current value $I$ will start to decrease as the wire heats up which will result in the reduction of the magnetic field assuming a fixed voltage value applied to the wire. 

So you see the magnetic field is always analogue to the current but a higher resistivity $ρ$ wire conductor for a given cross-section of the wire, will result to a larger drop of current with time for the same voltage applied. The higher the temperature increase on the wire the larger the reduction of its magnetic field. Magnetic field strength reduces with current reduction and temperature increase because there are less number of uniform direction flowing electrons and therefore less number of aligned discrete magnetic moments of electrons exist per unit of time which lessens therefore the magnetic field strength generated around the wire (i.e. magnetism is all about coherence, alignment and uniformity).

Two identical dimensions wires one from gold and the other from silver, for the same applied voltage will initially generate the same current value but with time the gold wire will increase more in temperature and experience a larger current drop and magnetic field strength drop than the silver. 

Also, resistivity $ρ$ of [material of conductor][3] does not remain fixed but increases with temperature which makes things even worse. The best solution is too keep things cool using higher cross-section wires.     


  [1]: https://hsisensing.com/temperature-affect-magnetism/#:~:text=Temperature%20affects%20magnetism%20by%20either,faster%20and%20more%20sporadic%20rate.
  [2]: https://en.wikipedia.org/wiki/Electrical_resistivity_and_conductivity
  [3]: https://en.wikipedia.org/wiki/Electrical_resistivity_and_conductivity#Resistivity_and_conductivity_of_various_materials