The phrase "spring evening" refers to an evening during the season of spring. It typically indicates a time when the weather is getting warmer, flowers are blooming, and the days are getting longer. Full definition
I think the key to dressing for spring even though it's still technically winter is layering spring prints under your sweaters or jackets. (jeansandateacup.com)
Thanks for giving us a shot of spring even though you're nearly frozen in. (elementsofstyleblog.com)