When will the heat break?

The chart below shows the 2007 season data, increasing heat and dew point, through March. It conforms to our recent experience of increasing discomfort as the hot season approaches. It follows the pattern you can see in the background of the major El Nino year of 1983. (However the 2007 data are from a new weather station downtown Bangkok, at Asoke, while the 1983 data (white points) are for Don Muang which for various reasons is consistently warmer than downtown.) The intensity of solar radiation for cleart weather is shown as a yellow line, you can see that the heat pattern so far follows solar intensity.

It is evident that we are on the same track as in the past, and that we can expect a "break" in the heat during the next month or two. The Thai say that Songran is the hottest day of the year and there appears to be good reason for this. If Bangkok were located at latitude 8 instead of latitude 15, April 15, Songran, would also be the longest day, the day of no noon shadow as well. Latitude 8 conforms to the location of southern Thailand, perhaps the early calendars were devised there.

Other years, not major El Nino years, show a break in heat earlier than 1983, which is extreme. Since 2007 is not a major El Nino year, we may expect an earlier break as in the the years 1984 and 1985, shown below.