* New front month still below recent 21-month high * Above-normal temperatures on tap but not extreme heat * Nuclear power plant outages back below normal * Coming Up: EIA natgas storage data on Thursday By Eileen Houlihan NEW YORK, May 30 (Reuters) - U.S. natural gas futures edged lower early Thursday, extending losses for a fourth straight session ahead of weekly government storage data expected to show a healthy build to inventories. In addition, traders said despite above-normal temperatures on tap for much of the nation in the coming days and weeks, it was not likely to be hot enough to spark heavy cooling loads yet. Most traders and analysts expect weekly data from the U.S. Energy Information Administration to show a build of about 88 billion cubic feet when it is released at 10:30 a.m. EDT (1430 GMT), a Reuters poll showed. Stocks rose an adjusted 72 bcf in the same year-ago week, and on average over the past five years have gained 92 bcf that week. The EIA will release its gas storage data for the week that ended May 24 at its usual time despite Monday's U.S. Memorial Day holiday. As of 9:13 a.m. EDT (1313 GMT), new front-month July natural gas futures on the New York Mercantile Exchange were at $4.142 per million British thermal units, down 4.2 cents, or about 1 percent. The spot contract 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 issued on Wednesday called for above-normal temperatures in the western third of the nation, in the Northeast and much of the Midwest, and mainly normal readings elsewhere throughout the country. Nuclear plant outages totaled 13,600 megawatts, or 16 percent of U.S. capacity, down from 15,700 MW out on Wednesday, 17,400 MW out a year ago and a five-year average outage rate of 14,400 MW.