Climbing Forecast › Flatirons › Third Flatiron

FLATIRONS · FOUNTAIN SANDSTONE

Third Flatiron climbing conditions

Poor — wet, too windy or closed

Right now

Temp78°F
Wind8 mph
Gusts12 mph
Humidity28.2%
Rain 48hdry
Last rainNone recent

Assessment

1.9mm rain forecast
Hot — fountain-sandstone slabs may feel greasy

7-day forecast

Scroll through each day — hourly detail is shown inline.

Today Monday 24 August
Poor
Temp81°F
Rain0.07 in
Wind7 mph
Gusts12 mph
Humidity25%
1.9mm rain forecast
  • Hot — Fountain slabs can feel greasy
  • Sun-exposed Fountain walls dry within hours; shaded lower walls take longer
Time °F Rain Wind (mph) Gust Hum
15:00 78° dry 8 — 28.2%
16:00 82° dry 6 — 22%
17:00 84° dry 7 — 19.9%
18:00 86° dry 10 — 19.2%
19:00 86° 0.01 in 9 — 20.7%
20:00 85° 0.04 in 9 — 20.8%
21:00 80° 0.02 in 12 — 32.8%
Tue Tuesday 25 August
Poor
Temp64°F
Rain0.2 in
Wind5 mph
Gusts—
Humidity56%
3.9mm rain forecast
  • Good friction range for Fountain sandstone
  • Sun-exposed Fountain walls dry within hours; shaded lower walls take longer
Time °F Rain Wind (mph) Gust Hum
06:00 64° dry 8 — 52.6%
07:00 61° dry 7 — 58.7%
08:00 61° dry 6 — 57.4%
09:00 59° dry 7 — 61.9%
10:00 57° dry 6 — 66.2%
11:00 55° dry 6 — 70.8%
12:00 55° dry 5 — 73.7%
13:00 56° dry 5 — 71%
14:00 67° dry 5 — 53.8%
15:00 77° dry 3 — 31.2%
16:00 80° 0.01 in 4 — 25.8%
17:00 81° 0.01 in 6 — 24.6%
18:00 82° 0.01 in 5 — 22.7%
19:00 84° 0.02 in 9 — 22.2%
20:00 78° 0.08 in 13 — 33.7%
21:00 72° 0.01 in 10 — 59.4%
Wed Wednesday 26 August
Poor
Temp61°F
Rain0.06 in
Wind4 mph
Gusts—
Humidity66%
1.5mm rain forecast
  • Good friction range for Fountain sandstone
  • Sun-exposed Fountain walls dry within hours; shaded lower walls take longer
Time °F Rain Wind (mph) Gust Hum
06:00 59° dry 8 — 79.5%
07:00 59° dry 9 — 75.9%
08:00 57° dry 7 — 76.4%
09:00 55° dry 6 — 78.6%
10:00 55° dry 4 — 78.1%
11:00 55° dry 4 — 74.6%
12:00 55° dry 4 — 72.1%
13:00 56° dry 4 — 67.6%
14:00 64° dry 3 — 54.5%
15:00 67° dry 4 — 56.4%
16:00 69° dry 5 — 57%
17:00 72° dry 5 — 50.2%
18:00 74° 0.01 in 6 — 48.6%
19:00 74° 0.01 in 5 — 46.1%
20:00 75° 0.02 in 7 — 42%
21:00 71° 0.01 in 6 — 52.4%
Thu Thursday 27 August
Poor
Temp52°F
Rain0.05 in
Wind2 mph
Gusts—
Humidity80%
1.2mm rain forecast
  • Good friction range for Fountain sandstone
  • Sun-exposed Fountain walls dry within hours; shaded lower walls take longer
Time °F Rain Wind (mph) Gust Hum
06:00 55° dry 5 — 94.4%
12:00 52° dry 2 — 80.3%
18:00 77° 0.01 in 6 — 37.1%
Fri Friday 28 August
Poor
Temp57°F
Rain0.01 in
Wind6 mph
Gusts—
Humidity63%
0.3mm rain forecast
  • Good friction range for Fountain sandstone
  • Fountain sandstone dries fast in the sun — adularia-cemented arkose behaves like granite, not desert sandstone
Time °F Rain Wind (mph) Gust Hum
06:00 60° dry 8 — 63.4%
12:00 57° dry 6 — 62.5%
18:00 85° 0.01 in 6 — 25.2%
Sat Saturday 29 August
Poor
Temp55°F
Rain0.02 in
Wind6 mph
Gusts—
Humidity66%
0.5mm rain forecast
  • Good friction range for Fountain sandstone
  • Sun-exposed Fountain walls dry within hours; shaded lower walls take longer
Time °F Rain Wind (mph) Gust Hum
06:00 63° dry 7 — 49.8%
12:00 55° dry 6 — 66.1%
18:00 89° 0.02 in 10 — 14.6%
Sun Sunday 30 August
Good
Temp61°F
Rain0.00 in
Wind8 mph
Gusts—
Humidity56%
Should be dry
  • Good friction range for Fountain sandstone
  • Fountain sandstone dries fast in the sun — adularia-cemented arkose behaves like granite, not desert sandstone
Time °F Rain Wind (mph) Gust Hum
06:00 64° dry 8 — 50.5%
12:00 61° dry 8 — 55.9%
18:00 85° 0.00 in 5 — 18.9%
Mon Monday 31 August
Good
Temp59°F
Rain0.01 in
Wind2 mph
Gusts—
Humidity59%
Should be dry
  • Good friction range for Fountain sandstone
  • Fountain sandstone dries fast in the sun — adularia-cemented arkose behaves like granite, not desert sandstone
Time °F Rain Wind (mph) Gust Hum
06:00 64° dry 8 — 43.9%
12:00 59° dry 2 — 58.6%
18:00 72° 0.01 in 5 — 38.8%
Access
East Face Standard (5.4, eight pitches)

About Third Flatiron

The Third Flatiron is the most iconic climbing formation in Colorado — a 1,300-foot east-facing tilted slab of Fountain Formation arkose rising above Chautauqua Park on the flank of Green Mountain, visible from every neighbourhood in Boulder. The is one of the busiest multi-pitch routes in the world — a rite of passage for every Front Range climber and a training ground for generations of Colorado alpinists. The tick list from easiest to hardest: East Face Standard (5.4), East Face Left (5.5, nine pitches), College Drop Out (5.6, six pitches), Friday's Folly (5.7), and Saturday's Folly (5.8+). The Fountain Formation adularia-cemented arkose here is exceptionally hard — Denver Gazette's geology piece specifically credits the K-feldspar cement for the Flatirons' resistance — and the east aspect means sun from roughly 9am to 3pm before the wall goes into shade. **Boulder OSMP raptor closures typically run February 1 – July 31** on the Third — extended into August in some recent years; check bouldercolorado.gov/services/osmp-closures before travelling. Approach ~40 minutes from Chautauqua Park; the standard descent is a fixed rappel down the west face. Free public access, OSMP land.

Region
Flatirons
Rock type
Fountain sandstone
Aspect
east-facing
Altitude
6736 ft
Exposure
medium
Seepage
low

Other crags in this region

First Flatiron