・・・。
The ski resort we finally made it to… the snow had turned to rain.
Literal
At-last arrived ski-slope... snow [subject-が] rain [to-に] was-changing.
A disappointing arrival. ようやく ('at last, finally') emphasizes the effort taken to get there. 辿りつく ('to finally reach, to arrive after struggle') is the compound 辿る ('to trace, to follow a path') + つく ('to arrive'), conveying the difficulty of reaching somewhere. 変わっていた is past progressive of 変わる, marking the 'had already changed to' resulting state. The trailing ellipsis creates a pregnant pause for the disappointing reveal. Classic narrative disappointment.