FEW MEASUREMENTS are more crucial to the culinary arts than temperature, time and weight. Yet accurate devices to record them are too often overlooked in the kitchen - sometimes with disastrous results.

While most amateur cooks recognize that oven heat is critical, few pay attention to the equally important measurements for the refrigerator and freezer, for food and sugar, and for deep fat.

An oven thermometer is essential for any serious cook because almost no ovens actually reach the exact temperature set on the dial. The only way to be assured of the correct temperature is to keep a thermometer inside the oven moving it about from time to time to identify uneven spots. If there are substantial temperature differences, it is often possible to correct the problem by turning your pot around at various times, evening out the temperature over the total cooking period.

There are a number of good thermometers available, especially those made by Taylor. They will measure from 100 to 680 degrees Fahrenheit, and can be hung from an oven rack by a hook on the top. The cost: $8.50.

Unfortunately, a freezer thermometer is usually on the bottom of the equipment shopping list. People reason that if they can see solidly frozen ice, the machinery must be working correctly. This is wrong: Anyone who has a freezer should have a freezer thermometer.

Enzyme action in food begins at any point above 4 degrees Fahrenheit.This chemical process will alter color, texture and flavor. A piece of meat held at zero for a full year will be of the same quality as one held for one week at 25 degrees Fahrenheit. Since water freezes at 32 degrees, ice will be solid and food will feel frozen to the touch at 25 degrees. But the food will not be properly protected against deteriorating enzymes at any temperature above 4 degrees.

A good freezer thermometer costs about $4 And at $3.98, a cook should also have a refrigerator thermometer with an easily legible shaded area between 35 degrees and 45 degrees - the proper temperature range.

The hands-down favorite of just about every cooking authority for an all-purpose thermometer is the Taylor Tiny Instant Bi-Therm. It can go into any food, and works in both solids and liquids. The dial is moisture-resistant with an unbreakable crystal. The thin stainless-steel stem is 5" long and extremely strong. The sheath has a pocket clip and a little loop near the end through which the thermometer can be slipped. The sheath can then be used as a handle to extend the thermometer over hot liquids.

This model has a range of 0 to 220 degrees F. and a nut for adjusting accuracy. It is advisable to buy adjustable thermometers whenever possible, and testing them is simple. Water (at sea level) boils at 212 degrees. Once the thermometer is immersed, the nut is turned to 212. The cost: $13.95.

The final device necessary for a basic kitchen is the deep-fat or sugar thermometer. Sugar has a completely different character at different temperatures; and a variance of a mere 2 or 3 degrees can make the difference between a recipe's success or failure. Deep-fat and oil cookery are not quite as sensitive, but a shift of 10 degrees can take food from crisp and oil-frr to soggy and grease-covered. Thermometers for this job should have a range of 100 to 400 degrees. The handle should be made of a material that does not conduct heat, and there should be a clip to hold the thermometer upright in a sauce pan or deep-fat fryer. The cost: $6.95.

Measuring Time

Time's winged chariot can be clocked with Terraillon Timers. Made in France, they have a design format so clean and functional that they have been made part of the permanent collection of The Museum of Modern Art in New York. And in addition to the chic, they are the best of class because of the crisp, loud, long, but pleasant ring. They also make a model with a rope to hang around the neck of the peripatetic chef. The Minitimer is $13; the Rope timer, $16. (Smith's of Great Britain also makes and exports a counter-top five-hour model that's excellent if hard to find.)

Measuring Weight

Americans do not do much measuring of ingredients by weight. But a scale in the kitchen can help keep butcher and fish dealer honest. The Terraillon BA 5000 Spring Scale, at $24, will give a fairly accurate reading up to 10 pounds or 5,000 grams.

The most accurate measure is, of course, a beam balance, but they are a bit cumbersome for limited use. However, when using the magnificient English Cookbooks of Elizabeth David, or once again trying to reproduce a splendid chocolate cake from hand-written recipe given me by a chef in the south of France, I love that little scale. CAPTION: Picture, Oven thermometer