Adamantium is indestructible; meaning it is completely resistant to any form of heat, light, radiation, force or electromagnetic manipulation. While beings such as Magneto have been able to push, pull or potentially manipulate the substance, it is considered by Marvel canon to be the most indestructible material on Marvel Earth-616.
A canon representation of the heat resistance of Wolverine's skeleton can be shown here from New X-Men #148 where his skeleton survives the heat of the sun!:
Adamantium's resistance to electromagnetic forces including forces such as magic and telekinesis, has always existed in the normal canon of the Marvel Universe.
This level of indestructibility is highlighted and illustrated by the best known example of Captain America's shield which is composed of Primary Adamantium, consider to be the strongest material in the Marvel Universe (that can be found on Earth...)**
Captain America's adamantium shield resists the powerful kinetic blasts of the mutant Cyclops.
See StackExchange Article: How does Captain America's shield work?
Captain America deflecting the cosmic radiation of the powerful mutant, Havoc.
The Wikipedia entry on Adamantium adds:
In the Marvel Universe, adamantium is a group of man-made metal alloys of varying durability, but all are nearly indestructible. Adamantium was inadvertently invented by the American metallurgist Dr. Myron MacLain in an attempt to recreate his prior discovery, a unique alloy of steel and vibranium (which required an unknown catalyst for its manufacture) that was used to create Captain America's shield.
This was established in Avengers (vol. 1) #66-68 (July – September 1969).
Before molding, the components of the alloy are kept in separate batches, typically in blocks of resin. Adamantium is prepared by melting the blocks together, mixing the components while the resin evaporates. The alloy must then be cast within eight minutes. Adamantium's extremely stable molecular structure prevents it from being further molded even if the temperature is high enough to keep it in its liquified form. In its solid form, it is colorless, shiny, and resembles high-grade steel or titanium.
Established in Avengers (vol. 1) #201-202 (November – December 1980)
It is almost impossible to destroy or fracture in this state and when crafted to a razor edge, it can penetrate most lesser materials with minimal application of strength.
Established in X-Men (vol. 1) #139 (November 1980)
Wolverine's skeleton is linked to a substance called beta adamantium. Wolverine's skeleton has not been completely replaced with adamantium. His bones have been laced and suffused with adamantium allowing them to become nearly unbreakable without adding significant weight to his body.
Adamantium's structure (defying the laws of physics as we understand them) once its form is set, it simply resists any form of physical transformation without an expenditure of cosmic forces, matter reorganization, or powerful magic. This means beings such as Magneto, Odin/Thor, the Silver Surfer, or the Phoenix are beings capable of manipulating or destroying adamantium beta.
See: Why did hot Adamantium not destroy Wolverine's body while replacing his skeleton?