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John Martin Reservoir sits in Colorado and is classified as a reservoir. At around 17,500 acres (about 27 square miles), it is a large waterbody. Research-grade observations nearby include Common Carp, Black Crappie, Channel Catfish, and Walleye. LakeRadar pulls readings from a mapped water gauge, so current water data is shown when the station reports. Coverage here includes an hourly and 7-day forecast, wind and gust outlook, water readings, fishing conditions, and activity scores for boating, paddling, and swimming. Forecasts for John Martin Reservoir come from the National Weather Service and refresh several times a day.
Updated
Latest source update is older than expected. Use caution and check the official source.
The last automated check (Oct 9, 1:55 PM MDT) found no active alerts for this lake, but that check is older than LakeRadar's alert freshness window, so the current alert status could not be confirmed.
Confirm before heading out: official alerts for this area or weather.gov/alerts. LakeRadar scores summarize available conditions and are not a substitute for official warnings, local rules, or on-water judgment.
Overall Good (83/100) across 4 activities. Best right now: Sailing (89/100).
How the score is calculated →Best good fishing window, averaging 78/100 across these hours. Afternoon hours (17:00 local). 0% chance of precipitation. Derived from the hourly forecast; official alerts are not forecast and are checked separately.
| Metric | 9p | 10p | 11p | 12a | 1a | 2a | 3a | 4a | 5a | 6a | 7a | 8a | 9a | 10a | 11a | 12p | 1p | 2p | 3p | 4p | 5p | 6p | 7p | 8p |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Temp (°F) | 86° | 88° | 85° | 82° | 77° | 71° | 68° | 66° | 65° | 64° | 62° | 61° | 59° | 57° | 55° | 54° | 53° | 57° | 61° | 69° | 74° | 80° | 83° | 85° |
| Wind (kts) | 9 | 13 | 13 | 17 | 17 | 17 | 17 | 17 | 17 | 17 | 17 | 17 | 13 | 13 | 9 | 9 | 9 | 9 | 9 | 13 | 13 | 13 | 13 | 13 |
| Direction | S | S | S | S | S | S | S | S | S | S | SW | SW | SW | W | W | W | W | W | W | W | W | SW | SW | SW |
| Gusts (kts) | 18 | 22 | 26 | 29 | 33 | 35 | 33 | 35 | 35 | 33 | 31 | 28 | 24 | 21 | 18 | 16 | 16 | 18 | 19 | 20 | 19 | 19 | 19 | 20 |
| Precip % | 0% | 0% | 0% | 0% | 0% | 0% | 0% | 0% | 0% | 0% | 0% | 0% | 0% | 0% | 0% | 0% | 0% | 0% | 0% | 0% | 0% | 0% | 0% | 0% |
| Time | Temp | Wind | Gusts | Precip | Cloud | Condition |
|---|---|---|---|---|---|---|
| Fri, 3 PM MDT | 86°F | 10 mph S (180°) | 21 mph | 0% | 2% | Sunny |
| Fri, 4 PM MDT | 88°F | 15 mph S (180°) | 25 mph | 0% | 2% | Sunny |
| Fri, 5 PM MDT | 85°F | 15 mph S (180°) | 30 mph | 0% | 5% | Sunny |
| Fri, 6 PM MDT | 82°F | 20 mph S (180°) | 33 mph | 0% | 4% | Clear |
| Fri, 7 PM MDT | 77°F | 20 mph S (180°) | 38 mph | 0% | 5% | Clear |
| Fri, 8 PM MDT | 71°F | 20 mph S (180°) | 40 mph | 0% | 5% | Clear |
| Fri, 9 PM MDT | 68°F | 20 mph S (180°) | 38 mph | 0% | 5% | Clear |
| Fri, 10 PM MDT | 66°F | 20 mph S (180°) | 40 mph | 0% | 3% | Clear |
| Fri, 11 PM MDT | 65°F | 20 mph S (180°) | 40 mph | 0% | 4% | Clear |
| Sat, 12 AM MDT | 64°F | 20 mph S (180°) | 38 mph | 0% | 3% | Clear |
| Sat, 1 AM MDT | 62°F | 20 mph SSW (203°) | 36 mph | 0% | 4% | Clear |
| Sat, 2 AM MDT | 61°F | 20 mph SW (225°) | 32 mph | 0% | 4% | Clear |
| Sat, 3 AM MDT | 59°F | 15 mph SW (225°) | 28 mph | 0% | 6% | Mostly Clear |
| Sat, 4 AM MDT | 57°F | 15 mph WSW (248°) | 24 mph | 0% | 3% | Clear |
| Sat, 5 AM MDT | 55°F | 10 mph WSW (248°) | 21 mph | 0% | 2% | Clear |
| Sat, 6 AM MDT | 54°F | 10 mph WSW (248°) | 18 mph | 0% | 1% | Sunny |
| Sat, 7 AM MDT | 53°F | 10 mph WSW (248°) | 18 mph | 0% | 4% | Sunny |
| Sat, 8 AM MDT | 57°F | 10 mph WSW (248°) | 21 mph | 0% | 2% | Sunny |
| Sat, 9 AM MDT | 61°F | 10 mph WSW (248°) | 22 mph | 0% | 2% | Sunny |
| Sat, 10 AM MDT | 69°F | 15 mph WSW (248°) | 23 mph | 0% | 1% | Sunny |
| Sat, 11 AM MDT | 74°F | 15 mph WSW (248°) | 22 mph | 0% | 1% | Sunny |
| Sat, 12 PM MDT | 80°F | 15 mph SW (225°) | 22 mph | 0% | 1% | Sunny |
| Sat, 1 PM MDT | 83°F | 15 mph SW (225°) | 22 mph | 0% | 2% | Sunny |
| Sat, 2 PM MDT | 85°F | 15 mph SSW (203°) | 23 mph | 0% | 2% | Sunny |
| Sat, 3 PM MDT | 88°F | 15 mph S (180°) | 23 mph | 0% | 1% | Sunny |
Official National Weather Service hourly forecast. Showing 10 of 25 hours. Wind arrows point the way the wind is blowing; the compass point and degrees show where it comes from.
| Period | This Afternoon October 9, 2026 | Tonight October 9, 2026 | Saturday October 10, 2026 | Saturday Night October 10, 2026 | Sunday October 11, 2026 | Sunday Night October 11, 2026 | Columbus Day October 12, 2026 | Monday Night October 12, 2026 | Tuesday October 13, 2026 | Tuesday Night October 13, 2026 | Wednesday October 14, 2026 | Wednesday Night October 14, 2026 | Thursday October 15, 2026 | Thursday Night October 15, 2026 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Temp (°F) | 88° | 53° | 89° | 62° | 88° | 63° | 88° | 56° | 77° | 53° | 72° | 49° | 70° | 45° |
| Wind | S 10 to 15 mph | SSW 10 to 20 mph | SW 10 to 15 mph | SSW 10 to 25 mph | SW 15 mph | SSW 15 to 25 mph | SW 15 to 20 mph | SW 10 mph | NE 10 to 15 mph | ESE 15 to 20 mph | SSW 15 mph | SW 10 to 15 mph | NW 10 to 15 mph | NE 10 mph |
| Gusts | 30 mph | 40 mph | 23 mph | 40 mph | 28 mph | 45 mph | 29 mph | 21 mph | 25 mph | 35 mph | 30 mph | 22 mph | 27 mph | 21 mph |
| Precip % | 0% | 0% | 0% | 0% | 0% | 0% | 0% | 1% | 9% | 21% | 17% | 14% | 12% | 15% |
| Forecast |
Nearby river temperature: 66.2°F at ARKANSAS RIVER BELOW JOHN MARTIN RESERVOIR, CO. (0.3 mi away) · Oct 9, 9:00 PM UTC
Good for fishing (81/100), from 5 available inputs. Supporting this: Wind 10 mph from the south. 0% chance of precipitation. Not available from a verified source for this lake: pressure trend, water temperature. Confidence is moderate (74%) because some inputs are unavailable or older than ideal.
Good for boating (82/100), from 4 available inputs. Supporting this: No active official alerts for this lake. Wind 10 mph from the south. Not available from a verified source for this lake: visibility and conditions, verified water access. Confidence is moderate (84%) because some inputs are unavailable or older than ideal.
Good for sailing (89/100), from 4 available inputs. Supporting this: Wind 10 mph from the S is in the preferred sailing range. No active official alerts for this lake. Not available from a verified source for this lake: visibility. Confidence is high (88%).
Good for kayaking (81/100), from 5 available inputs. Supporting this: Wind 10 mph from the south. No active official alerts for this lake. Confidence is high (90%).
Water temperature is not available from a verified source for this lake. No swimming score is shown without it.
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Individual boat ramp GPS coordinates are maintained under the jurisdiction of CO Parks & Wildlife Authority. Public boaters should verify seasonal launch water levels, gate hours, and daily vehicle/vessel fees before traveling.
John Martin Reservoir is a picturesque freshwater reservoir in CO known for its freshwater fishing, boating access, and attractive shoreline parks. With multiple recreation sites overseen by state and local natural resource agencies, visitors enjoy comfortable access to open-water cruising and shore angling. Always observe posted speed limits and maritime right-of-way rules.
Valid freshwater sport fishing license issued by Colorado Parks and Wildlife (CPW) is required for anglers age 16+. Digital license on mobile is accepted.
Mandatory Clean, Drain & Dry inspection. Out-of-area craft require on-site Aquatic Invasive Species (AIS Quagga/Zebra) inspection or decontamination before launch. USCG life jackets required for all.
Public shoreline and boating access managed by State & Local Authorities. Verify seasonal gate hours, launch fees, and parking rules before travel.
High-speed motorboating, pontoon cruising, wakeboarding, and water skiing across main channels. Target gamefish include Common Carp, Black Crappie, Channel Catfish, Walleye. Morning hours typically provide optimal glassy conditions for kayak and stand-up paddleboard (SUP) touring.
Warm water temperatures, peak swimming, active watersports, and open full-service campgrounds. Highest weekly attendance; plan early arrivals on summer weekends.
Spring pre-spawn and fall feeding transitions create prime trophy angling conditions. Cooler air, lower boat traffic, and vibrant seasonal shoreline foliage.
Mild year-round outdoor climate. Uncrowded waters, active winter bass and crappie fishing, and open year-round boat launch access.
No external source rows are cited by the data currently shown on this page.
Updated
Scores are heuristics, not safety guarantees. LakeRadar scores summarize available conditions and are not a substitute for official warnings, local rules, or on-water judgment.
All telemetry for John Martin Reservoir is synchronized directly from authorized federal and state monitoring networks (USGS, NWS, NOAA, and state environmental authorities). Observations are strictly instrumented readings — unmonitored sensors are transparently disclosed rather than synthetic estimates.
Last source audit: Oct 9, 3:30 PM MDT