Just about every miracle of Jesus has been questioned and replaced with some naturalistic explanation by those who do not believe. But take a look at the beginning of this account from the Gospel of St. John:
“When evening came, his disciples went down to the lake, 17 where they got into a boat and set off across the lake for Capernaum. By now it was dark, and Jesus had not yet joined them. 18 A strong wind was blowing and the waters grew rough.”
This short passage contains several details: 1) it was evening 2) it was dark 3) a strong wind was blowing and 4) the waters were rough.
You would think if it were actually cold enough that night to produce ice on the lake - an extremely rare if not probably nonexistent situation (the average temperature in Jerusalem in JANUARY is 43 deg F) - the Gospel passage would include that detail as well. Since it doesn’t, it is safe to say that it was not cold enough to produce ice on the lake.