Probability of a hard frost or freeze in the spring for some southwest Michigan fruit sites

A late spring can be a blessing in disguise. Late growth may mean fruit growers will avoid spring freeze injury.

Frosts and freezes in the spring are a hazard to fruit growers because freezing temperatures can kill actively growing shoots and flowers, destroying all or part of the fruit potential for the year. As overwintering buds develop, they become less and less resistant to cold (see the Michigan State University Extension article “Freeze damage depends on tree fruit stage of development”).

At bloom, fruit tree blossoms suffer damage just below freezing at about 28 degrees Fahrenheit. Because it has to get below freezing to cause injury, 28 F is often called a hard frost or a hard freeze to denote that the temperature was below freezing.

In 2012, fruit trees bloomed a month early and the normal freezes of April devastated the Michigan’s tree fruit industries. In 2013, we are one or two weeks behind normal development and tree fruit are only now entering the stage when hard freezes can cause damage. In many parts of southwest Michigan, there is only a 25 percent chance or less of a damaging freeze this spring. The possibility of a freeze continues to drop into early May. This means there is an excellent chance that there will be no freeze damage to fruit crops because the cool April delayed growth.

The National Weather Service has calculated the probability of a freeze for many of their long-term weather stations using data from 1951 to 1980. The table below is arranged from north to south. Sites located away from Lake Michigan show the approximate distance to the lake. Sites near Lake Michigan show no distance. In the table, 10 percent means there is a 10 percent chance of a freeze occurring on or after that date in the spring. Many gardeners worry about the last date when a temperature of 32 F will not occur. For more information on frost-free dates, see “Frost free dates: When is the last day my garden will get a frost?

Probability of indicated temperature or lower occurring on or before date in spring for southwest Michigan sites (1951-1980 data)

Holland - lakeshore

Temperature

90%

75%

50%

25%

10%

32

April 24

May 1

May 9

May 17

May 24

30

April 17

April 24

May 2

May 10

May 17

28

April 12

April 19

April 27

May 5

May 12

Allegan - 20 miles inland

32

April 23

April 30

May 8

May 16

May 23

30

April 17

April 24

May 2

May 10

May 17

28

April 7

April 14

April 22

April 30

May 7

South Haven - lakeshore

32

April 20

April 27

May 5

May 13

May 20

30

April 12

April 19

April 27

May 5

May 13

28

April 6

April 13

April 21

April 29

May 5

Bloomingdale - 15 miles inland

32

April 26

May 3

May 11

May 19

May 26

30

April 19

April 26

May 4

May 12

May 19

28

April 11

April 18

April 26

May 4

May 11

Paw Paw - 23 miles inland

32

April 25

May 2

May 10

May 18

May 25

30

April 22

April 29

May 7

May 15

May 22

28

April 16

April 23

May 1

May 9

May 16

Kalamazoo - 49 miles inland

32

April 24

May 1

May 9

May 17

May 24

30

April 18

April 25

May 3

May 11

May 18

28

April 9

April 16

April 24

May 2

May 9

St. Joseph - lakeshore

32

April 10

April 17

April 25

May 3

May 10

30

April 4

April 11

April 19

April 27

May 4

28

March 25

April 1

April 9

April 17

April 24

Eau Claire - 12 miles inland

32

April 19

April 26

May 4

May 12

May 19

30

April 12

April 19

April 27

May 5

May 12

28

April 5

April 12

April 20

April 28

May 5

 

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