Real Clear Politics sees this shaping up as a "wave" election

"In the last sixty years, five Presidents have gone into a midterm congressional election with their net approval at or below sea level: George W. Bush in 2006, Bill Clinton in 1994, Ronald Reagan in 1982, Lyndon Johnson in 1966, and Harry Truman in 1946. All five midterms were "wave" elections in which the opposition party picked up a large enough number of House seats to affect substantially the policymaking process in Washington, D.C."

RCP analayst: Dems could lose 80 to 90 House seats

I think those who suggest that the House is barely in play, or that we are a long way from a 1994-style scenario are missing the mark. A 1994-style scenario is probably the most likely outcome at this point. Moreover, it is well within the realm of possibility - not merely a far-fetched scenario - that Democratic losses could climb into the 80 or 90-seat range. The Democrats are sailing into a perfect storm of factors influencing a midterm election, and if the situation declines for them in the ensuing months, I wouldn't be shocked to see Democratic losses eclipse 100 seats.