dry spell

a dry spell (a period of time without success) — черная полоса, полоса неудач, полоса невезения

to have a dry spell (to go through a period of time when one is not getting what one wants) — попасть в полосу невезения; не везти

Example: She's is a great singer, though lately she's been having a bit of a dry spell. — ...последенее время ей как-то не везет; удача отвернулась от нее.

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A dry spell originally refers to a period of time when there is no rain, as in: "We've been having quite a dry spell lately; it hasn't rained in over two weeks."

see also
[bad patch]
[tough time of it]
[down on one's luck]
[черная полоса]
полоса невезения
полоса неудач
[не везет так не везет]
[бутерброд всегда падает маслом вниз]
[Hard lines!]

opp.
[полоса везения]