He said this is the time to raise cash. Cramer sold positions from his charitable trust in preparation and encouraged investors to do the same. He would rather miss a potential upside than get crushed in the market.
"Being prepared means selling or trimming not just stocks you're indifferent to, but even the stocks you like, betting that you can buy them back at a lower level," Cramer said.
Cramer warned that the Fed does not seem concerned about the economic data. It is worried that rates are at rare lows, which is untenable considering the unemployment rate and lack of overseas worries. It stayed on hold already because of China, oil and Brexit. Nothing overseas will stop it this time.
"Accept it and act accordingly, even if you think it won't happen or it shouldn't happen," Cramer warned.
With this in mind, Cramer outlined the stocks and events he will be watching next week.
Monday: Fed president speeches, United Natural Foods
Cramer expects Atlanta Fed President Dennis Lockhart to call for a rate hike on Monday. Things could get even worse when Minneapolis Fed President Neel Kashkari speaks in the afternoon, as he could also say the U.S. needs a rate hike.
Wednesday: German inflation data, Cracker Barrel, Citigroup analyst meeting
The U.S. sell-off began when the European Central Bank chose not to act aggressively to stimulate its economy, which indicated things have improved overseas. But with German inflation data coming on Wednesday morning that could be stronger, Cramer wants investors to prepare for wind in their faces before the market opens.
"I am sorry to be painting all of this data so negatively, and I don't mean to be an alarmist. I just think when you are walking through a minefield — as we are when we get closer and closer to the Fed meeting the week after next — it pays to know where the mines are," Cramer said.
For investors who think the Fed will raise rates, the banks could be the biggest winners. Cramer considers Citigroup the safest big bank to own. He has his eye on the analyst meeting. If the stock goes higher, it will tell the temperature of how the market feels about two rate hikes before the end of the year.
Thursday: Oracle, U.S. PPI data
The PPI data will confirm if inflation is rising in the U.S. Though, it may not matter what this report says, as Cramer suspects the Fed has already made up its mind about September.
Friday: U.S. CPI data
"I think that by then, everyone will know what I am telling you now, which is that we are on the verge of a rate hike. By this point, there will be almost universal concern that the Fed will lower the boom on Sept. 21. I say don't be tempted," Cramer said.
The key, he added, is to remember that when the last rate hike happened in December, investors had prepared. Yet it hammered the market. History can repeat itself, and investors should prepare their portfolios.