Kevin Myatt is The Roanoke Times' weather columnist.

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The first six months of this year were the warmest January-June period on record in the continental United States dating to 1895, according to the National Climatic Data Center in Asheville, N.C.

It was the warmest January-June period on record in five central U.S. states (Texas, Oklahoma, Kansas, Nebraska and Missouri) and ranked in the top quarter in every one of the "lower 48" states. It was the 13th warmest January-June on record in Virginia in the 112-year period of record, according to the center.

The average temperature for the continental U.S. during this time was 51.8 degrees F, which is 3.4 degrees above the average for the 20th century, according to the center.

Interestingly, Alaska was slightly cooler than normal during the first six months of 2006, going against the tendency of recent years.

Alaska had an extremely cold January while most of the U.S was experiencing unseasonably mild weather.

Roanoke's records do not go as far back as the center's national averages, only to mid-1948.

But still, I thought it would be interesting to see how the first half of 2006 ranked for us.

It wasn't the warmest January-June period on record in Roanoke, as it was nationally -- but it was the sixth-warmest.

The average temperature for our first six months was 54.67 degrees. That put January-June 2006 nearly 2.5 degrees warmer than the 1948-2006 average of 52.32 degrees, and almost a full degree cooler than the warmest January-June period on record, 55.62 degrees in 1990.

A year that starts warm usually ends warm, according to historical averages.

In 1990, Roanoke also recorded its warmest complete year in the books, the only year to average more than 59 degrees.

The city marked its second-warmest January-June period in 1953, and that was also the third-warmest complete year on record.

Then there was 1998, which vaulted from ninth on the January-June list to the second-warmest year overall.

Where 2006 will end up is as uncertain as the shifting jet stream.

It would probably already be higher on the list if a strong upper-level low hadn't set up over Hudson Bay in May and swirled unseasonably cool air down for two weeks.

As of Friday, July is almost a degree above normal. If July finishes that way, and we have average temperatures the rest of the year, 2006 will not rank among the 10 warmest years on record, but wouldn't be far behind.

So some above-average-temperature months from here on out could bump this year up the list.

Looking at the list of warmest years in Roanoke, you may notice a trend: Six of the 10 warmest years have occurred since 1998. Eight of the 10 warmest have occurred since 1990.

As national and worldwide temperatures are spiking, our local average annual temperatures are showing a tendency to be warmer as well.

However, there has been no greater tendency for extreme high temperatures. In fact, the number of record high temperatures set at the Roanoke Regional Airport is running behind the curve of what would be expected randomly both since 2000 and since 1990.

As previously noted in this column, we've had only three 100-degree days in 18 years, and none since 1999.

So how has it been getting warmer without extreme heat?

Warmer nights, I would say. We have an exaggerated tendency of late to set records for the warmest low temperatures, both in winter and summer.

Almost 40 percent of our record high minimums, or warmest lows for a given date, have been set between 1990 and 2005, even though that represents only 28 percent of Roanoke's period of record dating to 1948.

That's a subject I've written on before, and worth revisiting again sometime soon.