风中之烛

lit. like a candle in the wind, or frost on the roof (idiom); fig. (of sb's life) feeble

one's late days; to have one foot in the grave

to have only a breath of life (idiom)

precarious as the morning dew (idiom); fig. ephemeral and precarious nature of human existence

too weak to stand up to the wind (idiom); extremely delicate; fragile state of health

tossed about by the wind and rain (idiom); (of a situation) unstable