Pricier bread and cereal. Coming soon?

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NEW YORK (CNNMoney) -- Surging wheat and corn prices could hit the items in your grocery basket by mid-summer if planting conditions across the country don't improve.

It's a case of two extremes: dry weather conditions in parts of the southern United States and in Europe have sparked fears of a supply crunch of wheat, while supplies of corn are being threatened by flooding and heavy rain in the Midwest.

Wheat futures rose for a fourth consecutive session on Thursday, and prices are up more than 10% from a week ago. Corn futures were mixed Thursday after rising for five days, and are up nearly 12% over the past week.

While it typically takes time for increases in the futures markets to translate into price hikes at grocery stores, consumers could be in serious trouble if supplies continue to dwindle and prices keep going up.

The momentum for higher commodity prices

By July, farmers will be able to tell what state their harvests will be in, so that's likely when the price hikes at grocery stores would kick in...if unfavorable weather continues, said Jason Britt, president of Missouri-based Central States Commodities Inc.

As of Monday, the entire corn crop for the country was 63% planted, when the five-year average is 73%, according to the USDA. But for certain corn-growing states the conditions were much worse. For example, Ohio was 7% planted as of Monday, compared to a five-year average of 70%, while North Dakota reported that 14% of its crop had been planted -- compared to a 55% five-year average.

Meanwhile, wheat crops in Europe and southern U.S. states, such as Oklahoma, Kansas and Texas, have experienced the driest weather in decades.

"We could have some major fireworks in July -- no pun intended," said Britt. "If prices continue to push up, you're definitely going to have to see a reflection in prices at the grocery store -- the ramification of these higher prices is always going to be suffering for consumers."

Individual price increases at the store level won't likely be drastic. But there will probably be a noticeable difference in your total grocery bill, since wheat and corn are found in so many different food products -- including many staples like bread, cereal and corn oil.

"There's about seven to 11 cents of wheat in a loaf of bread, and a lot of your processed foods have wheat and corn in them," said Britt. "So your whole grocery bill would be reflected -- all the way from bread to corn syrup to meat, because higher corn prices translate into higher cattle prices when cattle are eating $9 corn."

Or retailers may do what many are already doing -- keeping prices the same but trimming the packaging.

"In this environment when consumers are already strapped, they have gotten really sensitive to price increases, so your grocery bill may stay the same but the amount of food you're getting is smaller -- so you may walk out of the store with the same bill, but the amount of food won't be the same," said Britt.

But if supply concerns level off and weather improves, retailers may be able to avoid passing along higher costs, said Britt. That means they probably won't do much before July.

Corn, wheat and other commodities

"This crop isn't dire yet, but they're sure not getting off to the start we were hoping for," said Britt. "This upcoming grains season is going to be one of the most important growing seasons yet."

So keep your fingers crossed for better weather -- not just for the farmers, but for you.

"People probably aren't looking at this flooding and bad weather and saying, 'wow this is going to make my grocery bill go up,' but that's where my thoughts go," said Britt. "They need to be rooting for this weather to stop."