The market rally won't last and this summer will be rough as the S&P 500 could go as low as 3,200, says Fairlead's Katie Stockton

• This summer will be rough for markets and more downside is possible, Fairlead's Katie Stockton told CNBC Tuesday.
• The S&P 500 is down roughly 14.4% year-to-date, though Stockton said the current relief rally will lose momentum.

US stocks have seen some relief in recent weeks, but the rally won't last and the S&P 500 still has downside potential, according to Fairlead's Katie Stockton.

"I think we're in store for a pretty rough summer," Stockton told CNBC Tuesday. "We do still have those negative momentum gauges intermediate and long-term."

Stockton maintains that the US is currently in a cyclical bear market within a secular bull market. The S&P 500 is down roughly 14.4% year-to-date, though the sell-off alleviated some as the index staged a 9% rally from its May 20 low.

She expects the rebound to lose steam soon, and said a 3,815 level for the S&P 500 "probably won't hold." On Tuesday, the index was down 0.5% at about 4,100.

"Importantly, the S&P 500, even though it might feel it, is not yet long-term oversold," Stockton said. "We still have some room for downside."

The market may establish a long-term low somewhere below 3,500, she noted, and relief may not arrive until around September this year.

"Short term up, intermediate and long-term down," Stockton said. "Worst case scenario is probably around 3,200 which is the second support, and that support would actually be targeted by a breakdown below that 3,815."