Campsite Odds

Booking odds · May

Mammoth Campground (Yellowstone) in May: How Hard Is It to Book?

Mammoth Campground (Yellowstone) · WY · Yellowstone National Park

The verdict

Plan ahead

Booking difficulty 4 out of 10. Books up in the weeks before popular dates. Reserve early.

Rarely sells outBased on 2 years of reservation data

May rarely sells out — you can often book close to your trip.

Mammoth Campground (Yellowstone) in May scores 4 out of 10 for booking difficulty — plan ahead. Books up in the weeks before popular dates. Reserve early.

Across the last 2 years of reservation history, the typical May booking was locked in about 11 days before arrival, with the campground running roughly 85% full that month. The lightest arrival day is Wednesday, so shifting to a midweek start is the single easiest way to improve your odds.

Lead time

How far ahead people book

Same day: 6% of bookings6%Same day1–3d: 22% of bookings22%1–3d4–7d: 14% of bookings14%4–7d1–2wk: 30% of bookings30%1–2wk2–4wk: 7% of bookings7%2–4wk1–2mo: 4% of bookings1–2mo2–3mo: 2% of bookings2–3mo3–6mo: 12% of bookings12%3–6mo6mo+: 4% of bookings6mo+Median booking lead time: 11 days ahead
Demand split

Weekend vs. weekday demand

Weekend (Fri–Sat)Weekday (Sun–Thu)

Best odds: arrivals are lightest on Wednesday in May. A midweek arrival is your easiest booking.

Booking window · May 2027

When May reservations open

Reservations for Mammoth Campground (Yellowstone) in May 2027 operate on a rolling 6-month window releasing at 7:00 AM ET.

May 1 stays open

November 1, 2026

at 7:00 AM ET

Release style

6-Month Rolling Window

Releases daily 6 months ahead at 7:00 AM ET

Campsites for May 1, 2027 become bookable on November 1, 2026 at 7:00 AM ET. Each subsequent date throughout May releases day-by-day exactly 6 months prior to arrival.

Facility note: Standard Recreation.gov 6-month rolling window: sites become bookable 6 months before arrival at 7:00 AM ET.

Fees

How much does it cost to camp at Mammoth Campground (Yellowstone)?

The camping fee in Mammoth Campground is $25 per night per site.

Fee details as listed on Recreation.gov. Rates and passes change by season, so confirm the current price on Recreation.gov before you book.

Plan B

Easier nearby options in May

If your dates are flexible, these nearby campgrounds are typically easier to book.

Headwaters Campground at Flagg Ranch

WYEasy

Colter Bay Tent Village

WYEasy

CLEARWATER CAMPGROUND

WYEasy

FAQ

Mammoth Campground (Yellowstone) in May: common questions

How hard is it to book Mammoth Campground (Yellowstone) in May?
Mammoth Campground (Yellowstone) rates 4 out of 10 for May — Plan ahead. Books up in the weeks before popular dates. Reserve early.
How far in advance should I book Mammoth Campground (Yellowstone) for May?
The typical May reservation was made about 11 days before arrival, so plan to book as early as your dates allow.
When do May reservations open for Mammoth Campground (Yellowstone)?
Reservations for Mammoth Campground (Yellowstone) in May 2027 open on a rolling 6-month window. Sites for May 1 become bookable on November 1, 2026 at 7:00 AM ET, with each subsequent day releasing day-by-day 6 months ahead.
What is the best day to arrive at Mammoth Campground (Yellowstone) in May?
Arrivals are lightest on Wednesday. A midweek arrival is usually the easiest booking.

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