* Front month remains well under recent 21-month high * Above-normal temperatures on tap but not extreme heat * Nuclear power plant outages remain above normal * Coming Up: EIA natgas storage data on Thursday By Eileen Houlihan NEW YORK, May 29 (Reuters) - U.S. natural gas futures were little changed to slightly lower early Wednesday, extending losses for a third straight session ahead of the June contract's expiration later in the day. While above-normal temperatures remained on tap for most of the nation for the next two weeks, traders said temperatures may not be hot enough to spark heavy cooling loads yet. As of 9:11 a.m. EDT (1311 GMT), front-month June natural gas futures on the New York Mercantile Exchange were at $4.16 per million British thermal units, down 1.4 cents. The front month hit a one-month low of $3.883 on May 9 after climbing to a 21-month high of $4.444 on May 1. The latest National Weather Service six to 10-day forecast and the eight to 14-day outlook, both issued on Tuesday, again called for above-normal temperatures for most of the nation. Nuclear plant outages totaled 15,700 megawatts, or 16 percent of U.S. capacity, up from 14,700 MW out on Tuesday and a five-year average outage rate of 14,300 MW, but down from nearly 16,000 MW out a year ago. Early injection estimates for Thursday's gas storage report from the U.S. Energy Information Administration range from 80 billion cubic feet to 103 bcf versus a 72-bcf build during the same week last year and a five-year average rise for that week of 92 bcf. The EIA will release its gas storage data for the week ended May 24 at its usual time, Thursday at 10:30 a.m. EDT (1430 GMT), despite the U.S. Memorial Day holiday on Monday.