Towards____ evening a cold rain began to fall.

morning, afternoon, evening 前面都要加定冠词the
其前面用介词的话要用in,towards等

前面不加冠词呀，towards evening 记成固定搭配也可以。傍晚时分

morning, afternoon, evening 前面都要加顶冠词the.
I take a shower in the morning, a beth in the evening.