Genesis 7 v 11:
In the six hundredth year of Noah's life, in the second month, the seventeenth day of the month, the same day were all the fountains of the great deep broken up, and the windows of heaven were opened.

Genesis 7 vv 15,16:
And they went in unto Noah into the ark, two and two of all flesh, wherein is the breath of life.
And they that went in, went in male and female of all flesh, as God had commanded him: and the LORD shut him in.

God sent a flood to destroy the earth because of man’s wickedness. Noah and his family were saved because Noah had fellowship with God obeyed His commands.

God sends the warning to all people today, that the time is coming when the earth will be destroyed - not by a flood, but by fire. Malachi 4 v 1 tells us:
For, behold, the day cometh, that shall burn as an oven; and all the proud, yea, and all that do wickedly, shall be stubble: and the day that cometh shall burn them up, saith the LORD of hosts, that it shall leave them neither root nor branch.

But the window of heaven is open to all today. All may come in repentance. All may call on the Lord and invite Him into their hearts and lives.
And all who accept Him shall be saved from that day of judgement and fire. Malachi 4 vv 2,3
But unto you that fear my name shall the Sun of righteousness arise with healing in his wings; and ye shall go forth, and grow up as calves of the stall.
And ye shall tread down the wicked; for they shall be ashes under the soles of your feet in the day that I shall do this, saith the LORD of hosts.