Learn Russian: Она ненавидит холодную погоду.

While reflexive emotion verbs like радоваться (to be glad) or удивляться (to be surprised) take the Dative case, ненавидеть (to hate) is not reflexive. It is a standard transitive verb. Just like любить (to love), it takes a direct object in the Accusative case.

The dictionary form is ненавидеть, which ends in -еть. Why is the 'she' form ненавидит spelled with an и?

Ненавидеть is one of the exceptions to the normal Russian conjugation rules. Despite ending in -еть, it belongs to the second conjugation. This means it uses -и- endings (ненавидишь, ненавидит) instead of -е- endings.

Is the verb ненавидеть related to видеть (to see)?

Yes! It is built around the root verb видеть (to see), historically expressing the idea of 'I cannot stand to look at it.' Because it is based on видеть, it follows the exact same irregular conjugation pattern.

As a quick refresher, why does the adjective холодную have a different ending than the noun погоду?