Can Moisture and Temperature Affect Neodymium Magnets?
Yes. Heat: standard N-grade neodymium magnets start losing strength permanently above 80°C (176°F) and lose all magnetism at their Curie temperature, about 310°C (590°F). High-temperature grades (M, H, SH, UH, EH, AH) are rated up to 230°C (446°F). Moisture: the iron-rich alloy rusts if water gets through the plating, so use coated magnets in damp places.
Temperature Limits by Grade
What Heat Does to a Magnet
| Temperature range (N grade) | Effect |
|---|---|
| Below 80°C (176°F) | Safe Small, temporary strength changes that recover as it cools |
| 80 to 310°C (176 to 590°F) | Permanent Partial Loss that grows with temperature and time |
| Above 310°C (590°F) | All Magnetism Lost until re-magnetized |
Shape Matters Too
Thin, flat magnets are more sensitive to heat than thick ones. A thin N42 disc in a warm enclosure can lose strength below 80°C, so leave extra margin or step up to an SH grade.
Cold Temperatures
Cold doesn’t hurt neodymium magnets. They actually get slightly stronger as they cool. (In extreme cryogenic conditions, below about −135°C (−211°F), standard NdFeB can behave differently, which matters only for specialized equipment.)
Moisture
Moisture doesn’t change the magnetic field, but it causes corrosion. Our magnets come with nickel-copper-nickel plating, which is enough for most indoor uses. See will neodymium magnets rust? and are neodymium magnets waterproof?