Kevin Myatt is The Roanoke Times' weather columnist.

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What defines a "heat wave" is open to interpretation. But what Southwest Virginia has experienced this month would qualify under almost anyone's definition.

You can make a sound case that August 2007 is already entitled to join the infamously hot summers of 1953, '77 and '83 as locally historic heat waves.

In Roanoke, the month has already produced one all-time record temperature, joined short lists of summers with multiple 100-degree days and temperatures of at least 102, and has exemplified sheer persistence of heat with 17 consecutive days of temperatures at or above 90 through Friday.

If the month ends up as Roanoke's warmest August -- or possibly even all-time warmest month -- on record, the case will be sealed.

During the first 16 days of the month, Roanoke had an average high of 94.8, an average low of 70.5 and an overall average of 82.7.

August records are 90.6 for an average high (1959), 68.7 for the average low (2005) and 79.1 for the overall average temperature (1959).

The all-time monthly records are 93 degrees for the average high (July 1977), 69.6 for the average low (July 2005) and 80.2 for the overall average (July 1993).

If half of the remaining days have near-normal temperatures and the other half are just a few degrees above normal, August 2007 will be in the running for any of these monthly records.

Normal temperatures are mid-80s for highs and mid-60s for lows, tailing off to the lower 80s and lower 60s by month's end.

Whatever happens the rest of the month, here is a list of heat feats that have already been established in Roanoke:

n Roanoke's all-time warmest night was set Aug. 9 with a low of 79 degrees, beating out the previous warmest night, 78, on July 7, 1977.

n Averaging the day's high and low, Aug. 9 was the second-hottest day on record in Roanoke. The high of 101 and low of 79 that day averaged 90 degrees. That trails only July 14, 1954, (high 104, low 77, average 90.5) and is tied with the day that produced Roanoke's all-time record high, Aug. 21, 1983, (high 105, low 75, average 90).

n The 17 consecutive days of temperatures at least 90 or above is tied for the second-longest streak with Aug. 12-28, 1959. The longest streak of 90 or above in Roanoke is 22 days, from June 23 to July 14, 1966.

n Thursday's high of 102 was the hottest day since it was 102 on Aug. 17, 1988, and it has not been hotter since it was 104 on Aug. 22, 1983.

n Only six of the other 58 years on record have produced as many or more 100-degree days as this summer, which has had three.

n Only five other years have had at least one day with a temperature of 102 or higher.

n Record highs for the date have been set on four days this month: Aug. 8 (100), Aug. 9 (101), Aug. 10 (99) and Aug. 16 (102).

n Records for warmest low temperature for the date have been set on five days this month: Aug. 6 (74), Aug. 8 (76) Aug. 9 (79), Aug. 11 (75) and Aug. 12 (72).

Blacksburg has also set some record highs this month, including 94 on Aug. 8 and 9, and 96 on Aug. 16.

It is worth noting that the official weather records at Roanoke Regional Airport began in 1948, so Roanoke's records do not reflect the extreme heat that hit Virginia and much of the nation in the 1930s and a few other years in the first half of the 20th century.

Lynchburg has set far fewer records than Roanoke this month.

Part of that is because it has generally been a few degrees cooler each day in Lynchburg than in Roanoke. But it's also partly because Lynchburg's weather records date to the 1890s and encompass some other extremely hot years.

If I were picking a gold medal summer for heat in Roanoke, it would be 1977.

Not only were there eight days at or above 100, but four days at 99 and five days at 97. There were no 90-plus streaks of more than 11 days, but there was one stretch when 18 of 19 days hit at least 90 and a second stretch where 16 of 19 days were 90 or above.

Whether this month continues to build on its historically hot resume all depends on how much cooler air from Canada and tropical moisture from the south can chew into the big, stagnant high-pressure system responsible for the heat.

So far, two cold fronts have been unable to stop Roanoke's 90-degree streak.

Another front moved through Friday, and many forecasts show highs in the 80s this weekend. But they did last weekend, too.

Once a heat wave gets rolling, sometimes it takes a hurricane to stop it.