168 
FLORIDA STATE HORTICULTURAL SOCIETY 
the Gulf of Mexico is colder. This has a 
tendency to draw the areas of high pres¬ 
sure farther south, so we may say that 
during areas of high maximum sun spots 
there are three forces working for cold 
snaps in Florida. (i) The average tem¬ 
perature in winter is actually lower than 
normal. (2) The variability of range in 
temperature between the highs and lows 
is greater than in normal years. (3) 
There is a tendency to draw these cold 
areas farther south than during normal 
periods. We are well aware that the cor¬ 
relation here is not close enough to war¬ 
rant any hard and fast prediction. It 
would seem, however, it is close enough 
to indicate what might be called strong 
possibilities. Leastwise, it was thought 
that the matter was of such importance to 
the citrus industry of Florida that the 
facts as they appear should be brought to 
the attention of this body of growers. 
The earliest freeze recorded (1766) oc¬ 
curred during a period of low.sun spot 
activity. A temperature of 20 degrees 
was reported near Jacksonville, but this 
was, of course, not an official record. We 
are told that citrus trees at St. Augustine 
were in fruit two years later, so it could 
not have been a very severe freeze. 
Of the six most severe freezes recorded 
for Florida (a temperature of 18 or low¬ 
er) all occurred during periods of high 
sun spot activity. If we call 20 degrees 
or lower a severe freeze there have been 
eight, seven in periods of maximum sun 
spots. If we adopt 25 degrees or lower 
as the standard freeze, there have been 
fourteen, ten during periods of sun spot 
maxima and four during periods of low 
sun spot activity. 
On the accompanying chart the sun spot ac¬ 
tivity is indicated by the solid line. On this line 
are indicated in dots the freezes, p,nd opposite 
them the lowest temperature. In most cases the 
temperatures are those of Jacksonville but a few 
^marked “G” are of Gainesville and one of Tampa. 
The dotted line on the chart indicates what 
we may expect in sun spot activity during the 
next few years. 
