Looking particularly in the direction of Kanna and Chick, Tarsin says, "I really don't want to get caught out in the open during a sandstorm. But we've also been told we need to hurry. I trust the judgment of you all with more experience than I in the open desert."
Chick makes gestures that indicate that if they hurry, the group should make the oasis before the storm, assuming there is one. The bigger issue may be if the Druid doesn't like us... or likes us too much.
So I have done the math you guys have currently been awake around 12 hours so pushing on to the oasis in 8 making it 20 hours awake if all is well buuuut if the sand storm bogs you down could be struggle anas you may need to make con saves to avoid fatigue. Just something to think about. You are riding a cart so you could push the Crodlu double time to arrive sooner but they would be making a con save every hour of double time.