What should I do about my father who refuses to عقد قراني (solemnize my marriage contract) to my fiancé, on the grounds that the proposed date is in winter, knowing that I desperately need him and cannot wait another year?

Delaying marriage may be acceptable for reasonable causes, in consultation between the guardian and the girl. However, it should not be delayed for flimsy reasons, as the Prophet, peace and blessings be upon him, said: "There are three things that should not be delayed: prayer when its time comes, a funeral when it is ready, and a previously married woman (or a single woman) when she finds a suitable match." The guardian should fear Allah concerning his ward and be gentle with her. He should know that delaying her marriage without a valid, recognized interest might incur the supplication of the Prophet, peace and blessings be upon him: "O Allah, whoever is given charge of any matter of my Ummah and makes it difficult for them, make it difficult for him." The girl, for her part, should be patient and try to convince her father directly or through someone who can influence him.