If I may... "Spring" as relates to garden planting is more readily determined by soil temperature (at least here in the U.S.) Soil temperature should be measured at 3 to 4 inches... any good thermometer can be used and should be taken over about a 4 day period and then the tempeatures averaged.
Cool season vegetables that can grow when the soil temperature is down to 40 degrees Fahrenheit include lettuce, kale, parsnips, peas, radishes and spinach. Cool season vegetables that can grow when the soil temperature is down to 50 degrees Fahrenheit include Chinese cabbage, onions, potatoes, Swiss chard and turnips. Cool season vegetables that can grow when the soil temperature is down to 50 degrees Fahrenheit include asparagus, beets, broccoli, Brussels sprouts, cabbage, carrots and cauliflower.
Warm season tcrops require near 65 to 70 degrees (F)... including tomatoes and cucumbers... beans can be grown at 60 degrees but won't survive a sudden late frost... (Source: University of Nebraska Agronomy).