A key inflation measure is spiking back up right before the Fed's rate decision, which is bad news for anyone hoping for lower rates or a calmer stock market.

• The Fed is expected to hold rates steady, but what Fed official Kevin Warsh says afterward matters more than the decision itself — hawkish language could send stocks lower.
• Inflation measures are turning worse: a widely watched private inflation tracker has risen sharply, and longer-term inflation expectations have climbed above recent ranges, echoing patterns seen before high-inflation periods in the past.
• Housing is weakening too, with falling home starts and sales and several straight weeks of declining mortgage applications, though builders expect that to ease once more homes get built.
• A strong earnings report from chipmaker SK Hynix is good for tech stocks but could backfire by signaling memory chip prices will stay high for years, giving the Fed another reason to stay tough on inflation.
• An unresolved conflict involving Iran is adding uncertainty; if a resolution happens before the Fed meeting, officials may feel freer to sound more relaxed about inflation.

Outlook: Expect a hawkish, cautious tone from the Fed that could rattle stocks in the short term, unless there's a surprise breakthrough on the Iran situation beforehand.