Combining 2 IF statements, getting nowhere and pulling hair out! ;)
If you want to do something when two or more conditions meets , use an and operator (&amp;&amp;), like this:

if (h &lt; humLowTrigger &amp;&amp; now.hour() == 15 &amp;&amp; now.minute() == 5) {
... do something ...
}


If you have a lot of conditional statements, you can simplify:

if (h &lt; humLowTrigger) {
   if (... other conditions 1 ...) {
     do something 1
     }
   ...
  if (... other condition n ...) {
     do something n.
     }
}


In your specific case:

if(h &lt; humLowTrigger) {
  if (now.hour() == 15 &amp;&amp; now.minute() == 5) {
    digitalWrite(A2, HIGH);
  }
  if (now.hour() == 15 &amp;&amp; now.minute() == 8) {
    digitalWrite(A2, LOW);
  }
  if (now.hour() == 15 &amp;&amp; now.minute() == 10) {
    digitalWrite(A2, HIGH);
  }
  if (now.hour() == 15 &amp;&amp; now.minute() == 12) {
    digitalWrite(A2, LOW);
  }
}


Better version

But there is a problem with the previous code, beacuse the mister must turn off no matter what the humidity level is. 

// Turn on only if humidity below threshold.
if (h &lt; humLowTrigger &amp;&amp; now.hour() == 15 &amp;&amp; (now.minute() == 5 || now.minute() == 10)) {
    digitalWrite(A2, HIGH);
  }
}
// Turn off always.
if (now.hour() == 15 &amp;&amp; (now.minute() == 8 || now.minute() == 12) {
    digitalWrite(A2, LOW);
   }