* Winter wheat contracts slip from 3- to 4-month peaks
* Recent run-up fueled by investor short covering
* Improved weather in Argentina weighs on corn, soy (Rewrites throughout, adds quote, updates prices, changes byline, changes dateline from LONDON)
CHICAGO, Jan 31 (Reuters) - U.S. winter wheat futures turned lower on Wednesday in a profit-taking setback from multi-month highs after five straight sessions of gains fueled by concerns over poor crop conditions in the United States.
Corn and soybeans were also lower as traders banked profits from a recent grain market rally and a slightly improved crop weather forecast for Argentina, where drought has reduced yield potential for crops.
"Today's lower trade is a day down in an overall two-week rally. I wouldn't say this is the end of the rally, certainly not for wheat," said Rich Nelson, chief strategist with consultancy Allendale Inc.
Chicago Board of Trade March soft red winter wheat fell 6 cents to $4.51-1/4 a bushel by 12:42 p.m. CST (1842 GMT) in the contract's steepest drop in 2-1/2 weeks. The contract hit a three-month high the previous day.
March K.C. hard red winter wheat fell 2-1/2 cents to $4.67-1/4 a bushel. The contract posted its strongest rally in seven months on Tuesday on record-large trading volume, hitting a four-month peak.
Condition ratings for winter wheat declined in January in several southern U.S. Plains states that have been hit by drought, including top producer Kansas, the U.S. Department of Agriculture said on Monday.
Dry weather is expected to continue for the central Plains wheat belt, sapping needed soil moisture from the HRW crop, forecasters said.
Corn and soybean traders are monitoring weather in Argentina as drought has reduced plantings and hurt yield potential for both crops. A slightly cooler forecast for the world's No. 3 corn and soybean exporter and top supplier of soymeal and soyoil weighed on corn and soy futures on Wednesday.
"Whenever you throw in some cooler temps, you're going to take some weather premium out," said Ted Seifried, analyst with Zaner Ag Hedge.
CBOT March corn declined 1/2 cent to $3.61 a bushel after reaching a 2-1/2 month high the previous day, on pace to snap a three-session streak of gains.
CBOT March soybeans were 6 cents lower at $9.94-1/4 a bushel, pulling back from Tuesday's near two-month high.
(Additional reporting by Naveen Thukral in Singapore and Nigel Hunt in London; Editing by Subhranshu Sahu, David Evans and Susan Thomas)