Clear Sky Confidence
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ECMWF IFS  ·  GFS Seamless  ·  HRRR CONUS
Dark Sky New Mexico · 31.9508, -108.8675 · America/Denver
Retrieved Oct 14, 4:31 PM. All three models were returned.
Night Wed Oct 14, 9:00 PM – Thu 6:00 AM
Verdict
Clear
Confidence
Trend
Stable
Clear at Opening
Yes
All-Night Clear
Yes
Expected Clear Hours
9.0 h
Longest Clear Window
9 h
Agreement
Strong
Deterioration
None
Hourly Forecast Details
Values are cloud cover percentages from each model.
●  Clear  ≤ 20%
●  Uncertain
●  Cloudy  ≥ 60%
Model values  =  Total, Low, Mid, High cloud %
T Total (all clouds)   L Low (near ground)   M Mid (mid-level)   H High (high altitude)
Example
7700
TLMH
Total 7%  ·  Low 7%  ·  Mid 0%  ·  High 0%
Time State Consensus
avg cloud %
 ECMWF GFS HRRR
TLMH TLMH TLMH
9:00 PM ●  Clear 0% 000000000000
10:00 PM ●  Clear 0% 000000000000
11:00 PM ●  Clear 0% 000000000000
12:00 AM ●  Clear 0% 000000000000
1:00 AM ●  Clear 0% 000000000000
2:00 AM ●  Clear 0% 000000000000
3:00 AM ●  Clear 0% 000000000000
4:00 AM ●  Clear 0% 000000000000
5:00 AM ●  Clear 0% 000000000000
Clear Nights
Clear nights since Jan 1: 160 of 286 nights
Average clear hours per night: 4.4 h
Updated Oct 14, 9:49 AM.
MonthClearNights
Jan1631
Feb1728
Mar2231
Apr1830
May2131
Jun1830
Jul931
Aug1531
Sep1130
Oct1313

A clear night has 4 or more clear hours (they need not be in a row) while the Sun is below −18°, using the same hour rules as the forecast. These figures come from archived model data (ECMWF, GFS and HRRR forecasts from the Open-Meteo history archive), not from direct sky observations. Weather data by Open-Meteo.com (CC BY 4.0).

About the Models
ECMWF IFS
High-resolution global model. Excellent for the middle and later hours of the night.
GFS Seamless
Global model. Good general guidance when you want a second opinion on the whole night.
HRRR CONUS
High-resolution, short-range model. Best for near-term conditions over the continental US.

Tip.  Look for strong agreement — hours where the three models show similar numbers — before treating the night as settled.

RetrievedVerdictConfidenceAgreementTrendClear hoursWindowData
Oct 14, 4:31 PMClear95 StrongStable9.09 hcomplete
Oct 14, 3:56 PMClear95 StrongStable9.09 hcomplete
Oct 14, 3:23 PMClear95 StrongStable9.09 hcomplete
Oct 14, 2:40 PMClear95 StrongStable9.09 hcomplete
Oct 14, 2:10 PMClear95 StrongStable9.09 hcomplete
Oct 14, 1:29 PMClear95 StrongStable9.09 hcomplete
Oct 14, 12:57 PMClear95 StrongStable9.09 hcomplete
Oct 14, 12:24 PMClear95 StrongStable9.09 hcomplete
Oct 14, 11:41 AMClear95 StrongStable9.09 hcomplete
Oct 14, 10:55 AMClear95 StrongStable9.09 hcomplete
Oct 14, 10:13 AMClear95 StrongStable9.09 hcomplete
Oct 14, 9:26 AMClear95 StrongStable9.09 hcomplete

Tonight looks clear, and the models support treating the night as clear through the window. No model shows a cloud increase through this night. The clear stretch runs through the whole night, not only the opening. Model agreement is strong. Recent runs are stable.

The verdict and confidence are calculated in the app. This explanation does not change them. Hour rules A clear hour needs consensus cloud at or below 20%, no scoring model above 25% total cloud, no scoring model above 40% high cloud, and at least 2 models reporting. A cloudy hour needs consensus cloud at or above 60%. Every other reported hour is Uncertain. A missing model is never filled in from another model. Night window Only hours with the Sun at or below -18° are scored. That is astronomical night. Expected clear hours count a clear hour as 1 and an uncertain hour as 0.5. Model weights Under 18 hours of lead time: HRRR 45%, ECMWF 30%, GFS 25%. From 18 to 36 hours: HRRR 35%, ECMWF 35%, GFS 30%. After 36 hours, HRRR stays on screen but drops out of the consensus. ECMWF is 55% and GFS is 45%. Weights are rescaled across the models that actually reported that hour. This run Dominant risk: No model shows a cloud increase through this night. Data quality: complete. Missing models: none. Agreement: strong. Trend: stable. Confidence steps Base for Clear: 78 Agreement strong: +12 Data complete: +6 Confidence 95

Summary cards are the decision. Verdict, confidence, and whether the opening and the whole night are clear stay in front. The icons match the words.

Colors mean the same thing everywhere. Green is Clear (consensus cloud at or below 20%, no model above 25% total cloud, and no model above 40% high cloud). Amber is Uncertain (the hour is reported, but it is not clearly clear or clearly cloudy). Red is Cloudy (consensus cloud at or above 60%).

Each model has four numbers. T is total cloud, all levels together. L is low cloud, near the ground. M is mid-level cloud. H is high cloud. A dash means that model did not report the hour. The blank is never filled from another model.

Consensus is the weighted average of the models that reported that hour. HRRR carries more weight in the next 18 hours. After 36 hours it stays on screen but drops out of the average.

Forecast History is earlier retrievals of this same site, so you can see whether the night is holding, improving, or deteriorating. Why This Verdict is the exact scoring for the night on screen.

Clear Sky Confidence

Version: 1.0.0 Build Date: October 2026 Guide Version: 1.0

Developed by erhAstro

Copyright © 2026 Eric Horton All Rights Reserved.

License

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Forecast Advisory

Clear Sky Confidence is an advisory forecasting tool only.

Forecast information is provided for planning and informational purposes and should not be relied upon as the sole basis for observatory operations, roof control, equipment protection, or safety decisions.

Users remain responsible for independently verifying weather conditions and maintaining appropriate safety systems.

Data Sources

Forecast data provided by Open-Meteo.

Weather model availability, accuracy, and forecast content are subject to change by the underlying data providers.

Documentation

Clear Sky Confidence User Guide

Guide Version: 1.0