German chancellor Angela Merkel laughs as she poses with a model dressed as crash test dummy at the IAA international car show in Frankfurt, September 13, 2007. REUTERS/Kai Pfaffenbach REUTERS/Kai Pfaffenbach The man who accurately predicted four market crashes to the exact date recently told Business Insider about his calendar prediction for when oil prices would start to significantly slump again.

Sandy Jadeja is a technical analyst and chief market strategist at Core Spreads.

Technical analysts look at charts to pinpoint patterns in various markets and asset classes. From that they forecast which direction prices are likely to move.

They can't tell you why there will be a big market movement, only that there will be one.

He says there is a specific time period to watch out for.

"Interestingly if we take a look at the chart [below], we can clearly see the technical indicator on the lower portion of the chart showing a potential move to lower prices," Jadeja told Business Insider. "This is a well-known seasonal effect that many commodities tend to follow and can be utilised for profitable trading.

"By observing data patterns we also note that there is an 80% probability of lower prices from July 2, right through to August 18. These type of patterns can be very useful to short-term traders who are either looking to profit from short-term trading opportunities or the longer-term trends as shown on the chart."

So basically, Jadeja sees there being significant weakness for the next three weeks:

As detailed before in a previous article on Business Insider, Jadeja has significant success with predicting when markets will crash, bottom out, or rise again. He also has told us about key dates when equity markets will see a downturn. You can read about those predictions here.

Sandy Jadeja is a technical analyst. Sandy Jadeja But oil is a tricky one. Oil, which cost over $110 a barrel in June 2014, is now trading at about $45 a barrel. At one point this year, it was touching $20 a barrel. So considering oil's current level, it looks as if prices are in a recovery.

But Jadeja said there would be a period of further downside trading that could provide a good opportunity to short sellers — people who bet against the performance of a company or asset and profit when the company stock or assets fall.

In trying to time the market, however, Jadeja noted the standard disclaimer that "past performance does not guarantee future certainty."