Temperature Heating of the earth's surface by the sun is the engine that makes the weather go. When clouds are present, they reflect away much of the sun's energy, keeping the temperature cooler. When there are no clouds, the sun's heat is able to come through, allowing the earth to heat up, producing warmer temperatures. Thus, in the summer, daytime temperatures near the ocean are cooler than those inland. At nighttime, because the ocean's temperature doesn't change very quickly, coastal temperatures are warmer.
Temperature is measured with a thermometer.
The mercury thermometer, just like the one you may have outside your window at home or at school, is still used by many weather stations to measure temperature. As the temperature rises, the mercury in the thermometer heats up and expands. This causes the mercury to rise and show a higher temperature reading. Cooling causes the mercury to contract, resulting in lower readings. Winds tend to carry weather along with them, so by looking upwind of one's location, the future weather can be predicted .