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• Note that the temperature 2-meters AGL (red trace) reaches a low temperature of 34 degrees F at 6am, while the sensor near ground level (blue trace) does indeed fall to 32 degree F from 6 to 7 am. So, while temperatures remained slightly above freezing a few feet above the ground, temperatures near the ground did in fact fall to freezing - allowing areas of frost to form.  Science in action!
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• What about my car or roof - they are above the ground and there was frost on them as well this morning?
• Certain materials like metal and glass radiate heat very efficiently, and therefore readily cool to the frost point. In addition, cars and rooftops are often better exposed (from multiple planes) and thus radiate heat more quickly than other objects. It should be noted that other meteorological factors such as wind speed and moisture also come into play when assessing the potential for frost. Subtle changes in these values can also be factors why one area sees frost and another nearby location does not. For instance, even a light wind speed of 3-5 mph can keep the atmosphere "mixed," thus preventing widespread frost formation.
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