May in Glacier National Park is a shoulder month: highs around 63°F, lows around 38°F. Crowds: quiet — #5 busiest of the park's 12 months. Waterfalls roar; the alpine is still buried. The editorial best window here is July–September. You get about 15h 16m of daylight. To finish Grinnell Glacier (4h 25m) before dark, leave the trailhead by about 4:42 PM.
Month data reviewed · how we check this
| Verdict | Shoulder Quiet and rewarding if you accept reduced services or weather. |
|---|---|
| Temps °F | 63° high / 38° low |
| Crowds | quiet · #5 busiest of the park's 12 months |
| What May is like | Waterfalls roar; the alpine is still buried |
| Best window (whole year) | July–September |
| Peak crowds (whole year) | Jul–Aug |
CROWDS: RELATIVE SEASONALITY FROM NPS VISITATION STATISTICS · TEMPS: APPROXIMATE NOAA NORMALS AT MAIN VISITOR ELEVATION — HIGH COUNTRY RUNS 10–20°F COLDER
DAYLIGHT ON MAY 15 · LOCAL PARK TIME (MDT)COMPUTED FROM THE PARK'S OWN COORDINATES FOR THE 15TH — THE MIDDLE OF THE MONTH STANDS FOR IT, AS IT DOES FOR CLIMATE NORMALS. WITHIN A MONTH THESE TIMES SHIFT BY UP TO AN HOUR
LEAVE THE TRAILHEAD BY — TO FINISH BEFORE DARK ON MAY 15WALKING TIMES ESTIMATED FROM EACH TRAIL'S MEASURED DISTANCE AND ELEVATION GAIN — A PLANNING FIGURE, NOT A PACE. ADD YOUR OWN MARGIN FOR PHOTOS, REST AND CROWDS. WATER AT THE COOL-WEATHER RATE, BECAUSE THIS MONTH AVERAGES 63°F. TRAILS WE HAVE NOT MEASURED ARE LEFT OUT RATHER THAN GUESSED
WHAT MAY ASKS OF YOU HEREGlacier National Park in June — Good, highs around 71°F, crowds: busy (long days; sun road usually opens late june – early july).
Our verdict for May is "Shoulder". Quiet and rewarding if you accept reduced services or weather. Expect highs around 63°F and lows around 38°F, with crowds at the "quiet" level. Temperatures are approximate NOAA normals at the main visitor elevation; crowd levels follow published NPS visitation statistics.
Across the full 12-month review, the best window is July–September, and the peak-crowd months are Jul–Aug. May itself we rate "Shoulder".
June we rate "Good" against "Shoulder" for May, with highs around 71°F and crowds at the "busy" level.
About 15h 16m on May 15: the sun rises around 5:54 AM and sets around 9:09 PM local park time (MDT). Computed from the park's own coordinates, so it is the light you actually get at the trailhead, not the nearest city's.
Grinnell Glacier takes about 4h 25m of walking, so on May 15 you would need to leave the trailhead by about 4:42 PM to finish before dark — the sun sets around 9:09 PM local park time (MDT). Walking times are estimated from each trail's measured distance and elevation gain, so treat them as a planning figure and add your own margin for photos, rest and crowds.
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