雪xuě上shàng加jiā霜shuāng

Literal: to add frost on top of snow
Figurative: One misfortune piled on top of another; a bad situation made worse at exactly the worst moment.

Where does 雪上加霜 come from?

It doesn't come from a particular anecdote, and its exact source isn't certain: the idiom's force lies entirely in the image. Frost settles on ground already buried in snow, and it doesn't even bring anything new: just more cold on top of the same cold. It fits misfortunes that come one after another, and it often follows 更是 or 无异于. It works as the mirror image of 锦上添花, "adding flowers to brocade": there something good is added to what was already going well; here, something bad to what was already going badly.

How is 雪上加霜 used? Two examples

他tā刚gāng丢diū了le工gōng作zuò，房fáng租zū又yòu涨zhǎng了le，真zhēn是shì雪xuě上shàng加jiā霜shuāng。
He just lost his job and now the rent has gone up too, one blow after another.
公gōng司sī本běn来lái就jiù困kùn难nán，这zhè次cì罚fá款kuǎn更gèng是shì雪xuě上shàng加jiā霜shuāng。
The company was already struggling, and this fine only made things worse.

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