Spring swings between warm and cold - be careful to stay warm.
Tips
history
From Li Qingzhao's 《声声慢》 (Song dynasty): "乍暖还寒时候,最难将息" - "at that warm-then-cold time, it's hardest to recover." One of the most quoted lines in classical ci poetry.
mistakes
还 here is read huán (4th tone, "return; again"), NOT hái ("still"). The phrase means "just warm, then cold returns."