The evidence is mounting that the US GDP report for the third quarter that’s due next month will reflect substantially slower growth vs. Q2’s strong 3.7% rise (seasonally adjusted annual rate). The mystery at this point is the degree of deceleration.

Current projections cast a wide net for Q3. On the low end is the Atlanta Fed’s GDPNow model, which projects a tepid 1.5% increase as of Sep. 17. On the high end is BMO Capital Markets’ outlook for a 2.8% increase. As for the crowd overall, The Wall Street Journal’s September survey of economists reflects an average Q3 rise of 2.4%.

Meanwhile, the Capital Spectator’s average Q3 GDP estimate via several econometric forecasts ticked up to 2.2% from last month’s 2.1% estimate.

The guessing game for the current quarter ends on Oct. 29, when the Bureau of Economic Analysis publishes its “advance” GDP estimate for Q3.

Worries about the potential for blowback from China’s slowdown have raised uncertainty about the strength of the US macro trend—uncertainty that appears to have convinced the Federal Reserve to delay raising interest rates last week. But Atlanta Fed President Dennis Lockhart yesterday said that a rate hike at next month’s policy meeting was a possibility:

Market volatility, if protracted, can be a channel for damping forces on economic activity. It’s too early to detect any significant impact on the real economy, to know whether any or all the factors I cited will evolve into a significant headwind.

For now, the available data shows that the “the economy is performing solidly,” Lockhart advised. “As things settle down, I will be ready for the first policy move on the path to a more normal interest-rate environment. I am confident the much-used phrase ‘later this year’ is still operative” for raising rates.

Nonetheless, there’s widespread agreement that the pace of growth is on track for a substantial slowdown in Q3 vs. the previous quarter’s impressive gain. But with the final month of Q3 numbers still missing, there’s still plenty of uncertainty about how the final round of figures will compare.