Everybody has his own vision of hell. Lately mine has been a second- floor bedroom with a western exposure and no air conditioner.

Let's face it. It's just too hot these days. Not just daytime hot, which is certainly bad enough, but nighttime hot. The kind of hot you can't escape by going to the mall, because the malls are closed.In the past couple of weeks, Salt Lake City has been setting new records for what the Weather Service calls "high lows" - or, in other words, nighttime temperatures that are so hot you wish you could donate your skin to science.

Nights so hot you never really fall sleep, you just lie suspended in time and space like sliced bananas in a bowl of Jell-O. Nights so hot you long wistfully for the cool, stale air of a January temperature inversion.

It wasn't always this way. Salt Lake City, after all, is located in the desert. That means it's supposed to have a desert climate: hot days, cool nights. Indeed, summer nights in Salt Lake City used to be crisp and pleasant, sometimes even chilly. On a crisp, pleasant, sometimes chilly late June evening you used to take a sweater along if you went out.

But a check with records kept by the National Weather Service's Salt Lake office shows that the past four Junes have presented a different sort of pattern. We've set several records for "high lows" this month, including a high low of 70 degrees in the early morning hours of June 23.

Seventy degrees is just not an acceptable temperature at night. When the thermometer only gets down to 70 - usually at dawn, just before you've got to get up anyway - it means that when you climbed into bed the night before at 10 or 11 or even midnight it was still maybe 80 or 85 degrees.

A look at Weather Service's rec-ords for the past 40 years reveals that the average minimum temperature for June nights is 53.9. But for the past four years the average June night has been as much 6.1 degrees hotter than that. In fact for the past 40 Junes the average low temperature has been 57 degrees or above only eight times and four of those times have been in the past four years.

In addition, notes William J. Alder, meteorologist in charge of the Salt Lake office, all the records for monthly high minimum temperatures for April, May, June, July, August and September have been set during the last five years.

It appears to be a trend, and the trend is apparently a legacy of the Floods of '83.

Mostly, the floods are just a soggy memory now. The damage they caused has long since been repaired, and out in the county, along Big Cottonwood Creek, the cloth sandbags that were never removed have pretty much rotted away. This year, the city's creeks are on the low side.

But out at the Great Salt Lake, the flood's memories are more lasting. The lake may be shrinking daily, but it is still big enough to cause a different kind of wind pattern. At night, when summer winds are usually calm, the bigger lake causes the winds to blow more strongly. All that increased circulation makes temperatures stay higher at night.

The bigger lake also increases the city's humidity, which also keeps the nighttime air from cooling off as much as it would if the air were dry. Adding to the problem is a tropical weather pattern that has been over the state for the last couple of weeks, bringing with it a cloud cover at night that traps in the heat.

Dean Hudson, a dispatcher in the repair department at ESCO Heating and Air Conditioning, says his company has seen "about an 800 percent" increase in calls since last weekend. At many air conditioning stores around the valley there are backlogs on service calls.

"When we say we can't come for a week," notes Guy Hemmert of Aire-Flo Heating and Electric, "they say,`A week! I'm dying!' "

Meanwhile, forecasters predict that the July-type weather pattern we've been experiencing in June will continue into the month that it rightly belongs in. The dog days of August won't be far behind.

But cheer up. There are only 183 more shopping days until Christmas.