Expect more volatility during the next few months because things may get worse before they get better, Marc Haefele, head of investment at UBS Wealth Management, warned CNBC.

Investors with a short time-horizon who are concerned about market volatility due to the Greek elections this month should cut back on stocks and wait for safer times. The longer the eurozone crisis continues, the more strain it will put on the U.S. economy, the UBS brokerage arm stated in a note to clients, according to CNBC.

European shares, including central and Eastern European, and emerging-market stocks are most at risk, according to UBS researchers.

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Although Haefele told CNCB there's not more than a 20 percent chance that Greece will leave the euro, he says he thinks the crisis won't be resolved this summer.

Still, most investors shouldn't run for the exits. If they have the stomach for upcoming volatility, they may see long-term gains. UBS believes the U.S. has one of the stronger economies and that American stocks are the best bet.

U.S. corporate profits, Haefele told CNBC, are still healthy and balance sheets are strong.

UBS especially likes high-yield credit.

“It’s positive on the year," Haefele told CNBC. "And with this recent market volatility, the spreads have come out again, so there is an opportunity for investors to get back in.”

A BMO Financial Group survey of Canadian investors showed that almost three-fourths of Canadian investors think volatility is here to stay.

"Several factors lead us to conclude that volatility will continue to characterize the financial markets for the foreseeable future," says Rajiv Silgardo, co-CEO of BMO Global Asset Management, in a news release.

"These include ongoing pressures in the euro zone, higher inflation rates in China, tensions in the Middle East and a tentative U.S. economic recovery."

In response, investors should turn to defensive sectors like consumer staples, telecom, utilities and healthcare, says Paul Taylor, CIO of BMO Harris Private Banking and BMO Global Asset Management.

Almost half of investors surveyed say volatility poses a good opportunity to invest, and only 28 percent see the current climate as a negative.

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