I have grown up with drought. My father, a farmer, used to look up at an overcast sky and shake his head sadly saying “There’s enough blue sky to patch a Dutchman’s trousers, so it won’t rain.” I was always intrigued by this expression, which I never heard being used outside my family – although I have passed it on to mine. He explained that ‘Dutchman’s trousers’, was a nautical term referring to the patch of blue sky that appeared when the weather broke, indicating fine weather to follow. The phrase refers to the very wide-legged blue pants that Dutch sailors used to wear – and which obviously needed to be patched from time to time.

While searching the Internet to verify this, I came across this interesting and informative song composed by Tom Lewis:
Dutchman’s Trousers
In the times when I was nothing but a lad,
I never did see much of m’Dad,
Oft’times that was reason to be sad,
For him and m’Granddad too were deep-sea sailors,
But m’Grandmother took me for walks by the sea,
To teach me the ways that the weather can be.
She’d study the sky and say to me:
“There’s just enough blue to patch a Dutchman’s trousers.”
“In the wintertime when the North winds blow,
And the sky takes on a silvery glow,
That’s a certain sign that it’s going to snow.
You must be ready to chip the ice from the rigging,
But if the wind is from the Southwest,
And the spray’s being blow back from the wave’s crest,
Batten down the hatches and hope for the best,
If you’re lucky you’ll see the blue of the Dutchman’s trousers.”
Chorus:
The Pilot gives us a “farewell” hail,
Haul on the halyards of the mainsail,
The wind is steady, there’s a following gale,
With just enough blue to patch a Dutchman’s trousers.
So when I became an Able Hand,
I remembered the lessons that I learned from m’Gran
The mates would call me: “the weather-man,”
On each ship I was the one with the reputation,
Who knew if a breeze or a gale would blow,
When I came on deck from down below
The Skipper would always want to know:
“Will there be enough blue to patch a Dutchman’s trousers?”
Where the saying came from I really don’t know,
The Hollanders used to be our foe,
That was a very long time ago.
For centuries now we’ve sailed the seas together.
From the great Southern Ocean to the Mediterranean,
On a sailing ship or a submarine,
The days are few and far between
When there’s not enough blue to patch a Dutchman’s trousers.