Those temps are fine. Your snake can easily tolerate the four degree swing in temps on the hot side. If the cool side gets too low, the snake just won't go there or stay there. Remember that snakes have evolved over hundreds of millions of years to survive in conditions significantly less stable then the tank you are providing. Getting a better enclosure and a UTH will help, but right know your snake is not in any danger.

My hot side is usually 88, and my UTH never goes above 90. My snake eats like a pig, is getting bigger, sheds regularly and is thriving.

Trust me, 89.3 is just fine, so is 93.2. In fact, don't even bother measuring tenths of a degree. Hot sides should be 88-93. Cool sides can drop down to the seventies. Sometimes in winter my cool side hits 69. My snake doesn't care, because she is curled up in the middle of the cage in a hide that runs 83-85 degrees.

If you want to make sure your snake has access to a 90 degree spot, install a UTH set to 90 with a thermostat, and put a hide on the warm end, the hide will remain at the high temp even if the tank cools down a little.

David