Best time to fly Helena to Denver
Every month pooled across the years on record, so "July" means July generally rather than one particular July. Full HLN to DEN record →
Best month
March
87.7% on time · 124 flights
Worst month
June
61.5% on time · 150 flights
| Month | Flights | On time | Cancelled | When late, by |
|---|---|---|---|---|
| January | 124 | 78.7% | 1.61% | 98 min |
| February | 112 | 74.8% | 0.89% | 83 min |
| March | 124 | 87.7% | 0.81% | 96 min |
| April | 120 | 81.7% | 0% | 104 min |
| May | 134 | 81.8% | 0.75% | 127 min |
| June | 150 | 61.5% | 1.33% | 109 min |
| July | 153 | 61.9% | 1.31% | 110 min |
| August | 155 | 68.9% | 1.29% | 143 min |
| September | 150 | 75.8% | 0% | 87 min |
| October | 149 | 87.2% | 0% | 172 min |
| November | 118 | 82.6% | 1.69% | 141 min |
| December | 124 | 82.3% | 0% | 106 min |
What a seasonal pattern can and cannot tell you
Months differ for reasons that repeat — summer thunderstorms in the American interior, winter fog and de-icing in northern Europe, school holidays filling every seat and leaving no slack in the schedule. Those are real and they come back each year.
What the pattern cannot do is forecast a particular flight. A quiet month has late days and a bad month has punctual ones. Treat this as a way to choose between two dates you are indifferent about, not as a promise.