How many chill hours your location has had this winter, against the average winter. Pick a fruit tree, berry or nut to see its chill needs and how cold it takes. For heat and harvest timing, use the Degree Day Calculator.
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Diagnose a plantFruit trees, many berries and nut trees need a winter's worth of cold before they bloom well, and nurseries rate each variety in chill hours: hours spent between 32 and 45 °F. Too few and buds open late and unevenly; that's why growers in mild winters pick low-chill varieties. This tool tallies this winter's hours from October 1 against the average winter. Each day's hours are estimated from its high and low, with the temperature taken as a smooth curve through the day, so a day from 30 to 50 °F counts about 11 hours. It works for US locations for now, using weather records and the average winter.
Too much chill doesn't hurt; a rating is a minimum. What stops a fruit crop in a cold place is the cold itself, so this tool also shows the coldest nights: this winter's so far, and the typical and coldest of the past ten winters, against how cold the crop takes. A variety rated for your zone, snow cover and a sheltered spot all help, and plants that meet their chill early can leaf out in a warm spell and lose the year's flowers to a late frost.
Chill ratings are regional guides. Check the nursery tag for the variety you buy, and ask your local Extension office which varieties do well near you.