Over the past 140 years or so, the Salt Lake Valley and Utah haven't always been blanketed with snow at Christmastime, but there's usually ample snow and accompanying cold temperatures.

"In reviewing diaries of early pioneers, we find that Santa was able to use his sleigh more often than not. But there were many mild Christmas Days with little or no snow, too," said William J. Alder, meteorologist in charge of the Salt Lake office of the National Weather Service.To check on the weather back through the early days, Alder, who has headed the Weather Service's Utah office for nine years, searched journals of early pioneer leaders and other records.

The journals, he said, give insight about weather conditions in the Salt Lake Valley shortly after the arrival of the pioneers.

In his journal, Apostle Parley P. Pratt reports that the fall of 1847 was mild, with planting of wheat continuing into December.

"Sometime in December 1847 . . . having finished sowing wheat and rye . . . I started in company with Brother Higby and others for Utah Lake with a boat and a fish net. A beautiful sheet of fresh water. Here we launched our boat and sailed up and down the lake shore on its western side for many miles . . . Arrived in Salt Lake City having devoted nearly one week to our fishing . . . hunting and exploring expeditions. During all this time . . . we had fine weather and warm days. But the night we arrived home was a cold one with a severe snowstorm."

Orson Pratt, another early-day Mormon leader, says in his journal that the winter of 1848-49 was severe, with temperatures dropping to 33 degrees below zero Feb. 5, 1849. Similarly, the winter of 1849-50 was also very severe, with deep snow and very cold temperatures.

Alder said the first official weather station in Utah was opened Feb. 1, 1870, at what is now Corinne, Box Elder County. In March 19, 1874, the U.S. Army Signal Service began keeping weather records in downtown Salt Lake City.

The coldest Christmas Day on record was 1879, when the maximum temperature climbed to only 14 degrees, with the minimum reported at 10 below zero.

In March 1928, weather service operations were moved to the Salt Lake International Airport, where climatological data since that time indicate that there was a trace or more of snow on the ground 37 Christmases, or 62 percent of the time. But the percentage drops to 40 percent for years with an inch or more, Alder said.

The greatest snow depth was 14 inches on Christmas 1932. Thirteen inches was recorded on the ground at the airport by the end of Christmas Day 1983. That was also the last Christmas that a measurable amount of snow - 3.9 inches - fell at the airport.

There was a period in the mid-1980s when things were were kind of brown during Christmas, but in 1983, 1987 and again this year, the Christmas season has been marked with plenty of the white stuff.

Alder said the greatest amount of snowfall in a 24-hour period was 5.9 inches on Christmas Day 1943.

At any rate, a white Christmas is ensured for all of Utah this year. Still another in a series of storms is forecast for Christmas Eve or Christmas Day and stretching into Monday.

"So Santa Claus must be kissing Mother Nature under the mistletoe . . . Fa-la-la-la-la," Alder said with a twinkle in his eye.