Polish annual inflation eased to 1.4 percent, below analysts' 1.7 percent forecast, from January's 1.9 percent.
The Polish central bank (NBP) lowered its inflation forecasts last week. Its governor, Adam Glapinski, shocked markets by saying any increase in the bank's record-low interest rates should not come before the end of 2020 in his view.
Polish markets are still pricing in the start of a normalisation of interest rates from next week.
But economic figures are closely watched for guidance over inflation trends which influence how loose monetary policy will be.
The zloty weakened after the inflation data to trade at three-month lows 4.215 against the euro at 1013 GMT, down 0.4 percent from Wednesday.
It remains near the range of the past two weeks of around 4.2 as investors weigh the negative impact from a possible delay in monetary tightening against the prospects for healthy economic growth.
Polish 5-year government bond yields dropped 9 basis points to 2.39 percent. The 10-year yield slipped 5 basis ponts to 3.26 percent.
Erste analyst Katarzyna Rzentarzewska said she would review her forecast that the first rate hike could come already in the first quarter of 2019.
"Such a development brings downside risks for our current yield forecasts as well as supporting a weaker zloty," she said in a note.
A strong inflation rebound in the second half of 2018 remains likely, Capital Economics said in a note.
"As a result, we expect the first hike in the policy interest rate before the end of the year," the note added.
The index of Warsaw-listed banks, which could benefit from higher interest rates, fell 0.7 percent, while the Warsaw bourse's bluechip index was up 0.25 percent, rising in tandem with the region's and Western Europe's main bourses.
The shares of Poland's leading insurer PZU rose 1.8 percent, after the company reported a more than 50 percent rise in net profits in 2017.
Stocks in Prague and Bucharest firmed slightly. Budapest markets are closed for the week due to Hungary's March 15 national holiday.
The Czech crown firmed slightly to 25.424 against the euro after figures showed slower, but still strong, annual growth in industrial growth of 5.5 percent and an 8.2 percent surge in retail sales.
Czech inflation also slowed below the central bank's (CNB) target in February, but the bank's Governor Jiri Rusnok said on Monday the trends still created room for interest rates to rise further.
In euro zone members Slovenia and Slovakia, government bonds were little changed despite increased political uncertainty.
Slovenian Prime Minister Miro Cerar resigned late on Wednesday after the Supreme Court annulled the result of a September referendum.
Slovak Prime Minister Robert Fico has also offered to resign following mass protests over the killing of an investigateive journalist.