* Q4 EPS 20 cents vs Street view 13 cents
* Q1 EPS forecast below Street view, full-year in line
* Shares down 4.9 pct (Adds analyst quote, details, changes dateline from NEW YORK)
DETROIT, Jan 27 (Reuters) - Royal Caribbean Cruises Ltd (RCL.N) (RCL.OL) forecast current-quarter earnings that fell short of market expectations after a key measure of revenue performance missed analysts' targets in the fourth quarter.
The world's second-largest cruise operator said its net yield, a measure that takes into account operating costs and the number of days at sea, was 3.2 percent in the latest quarter, shy of analyst expectations of about 5 percent.
The company, whose shares fell 6.5 percent, blamed "extreme" weather for the miss, saying the yield would have been 4.7 percent on a constant currency basis if had the weather had been more normal.
Royal Caribbean did report a higher-than-expected fourth-quarter profit, however, and Chief Executive Richard Fain said bookings were off to a solid start this year.
Cruise prices are also rising and expenses are dropping as a result of cost controls, he added. Still, the company's first-quarter outlook disappointed the market.
Royal Caribbean said it expected per-share earnings of between 10 cents and 15 cents, compared with Wall Street's forecast for 26 cents, according to Thomson Reuters I/B/E/S.
For the year, it said it expects to earn in the range of $3.25 to $3.45 per share. The mid-point of $3.35 per share is above the $3.31 analysts are expecting.
Larger rival Carnival Corp (CCL.N) provided a better-than-expected 2011 forecast last month, citing improving booking trends. [ID:nLDE6BK1HD]
"Today's earnings were a mixed bag," Hudson Securities analyst Robert LaFleur, who has a "buy" rating on the stock, said in a research note. "Without disruptions, yields were in line."
Fain said bookings in the key "wave" selling season, which runs from January to March, were off to a good start, supporting the company's earlier confidence in "meaningful pricing recovery and record financial performance in 2011."
Royal Caribbean earned $42.7 million, or 20 cents per share in the fourth quarter, compared with $3.3 million, or 2 cents per share, a year earlier. Analysts had expected 13 cents.
Total revenue rose 10.5 percent to $1.6 billion, less than the $1.64 billion analysts had expected. Revenue from passenger tickets, which make up nearly three-quarters of the total, rose 11.4 percent.
Fain also said the time may be right to build a new ship, which would likely be the start of a new series of ships once a deal was finalized.
Royal Caribbean's shares down 4.9 percent at $47.5 in afternoon trading on the New York Stock Exchange. The stock price hit an almost five-year high of $49.96 last week.