Canyonlands National Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Canyonlands National Park clear sky chart from 2005-11-06 to 2026-09-29.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.

Observation Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(no limit)	Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

By Month

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

		Occurrence of each Forecast	Data Points
Cloud Cover	Day	2 3 1 4 3 4 4 4 6% 8% 61%	157285
	Night	2 4 2 5% 4 4 4 4 6% 9% 56%	151759
Transparency	Day	20% 4 8% 21% 25% 21%	152105
	Night	22% 4 9% 22% 25% 18%	147946
Seeing	Day	7% 11% 24% 31% 21% 6%	17411
	Night	5% 6% 19% 40% 26% 4	27782

By Month

Percentage Cloud Cover SW (2006-)
Color Meanings: Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	2 6% 2 8% 6% 6% 7% 5% 6% 9% 43%	5318
	11th to 20th	Day	1 3 1 5% 3 4 4 4 6% 9% 58%	5340
	21st to end	Day	3 6% 2 5% 4 4 5% 4 6% 8% 52%	5844
February	1st to 10th	Day	2 5% 2 9% 7% 5% 5% 5% 6% 10% 45%	1890
	11th to 20th	Day	4 6% 3 6% 6% 5% 5% 5% 7% 10% 44%	1845
	21st to end	Day	3 6% 2 5% 5% 4 5% 4 6% 9% 51%	1801
March	1st to 10th	Day	1 4 2 5% 4 4 5% 4 6% 7% 57%	5064
	11th to 20th	Day	3 10% 3 6% 5% 5% 5% 4 6% 7% 44%	5110
	21st to end	Day	3 6% 3 7% 5% 4 5% 4 6% 8% 48%	5607
April	1st to 10th	Day	3 4 2 4 4 5% 4 3 6% 7% 58%	2405
	11th to 20th	Day	2 4 1 5% 4 5% 4 4 6% 9% 57%	2491
	21st to end	Day	2 3 1 3 4 4 4 4 6% 9% 60%	2664
May	1st to 10th	Day	2 3 1 4 3 3 4 4 5% 8% 62%	7626
	11th to 20th	Day	1 2 1 4 3 3 4 3 5% 7% 67%	7596
	21st to end	Day	2 2 1 3 3 3 3 3 5% 7% 70%	8370
June	1st to 10th	Day	2 2 1 2 2 2 3 3 6% 8% 69%	2824
	11th to 20th	Day	1 2 1 3 2 2 2 3 4 6% 76%	2939
	21st to end	Day	1 2 1 2 2 2 3 3 4 7% 73%	2731
July	1st to 10th	Day	1 1 2 2 2 3 2 4 5% 78%	7649
	11th to 20th	Day	1 2 1 3 3 4 5% 4 9% 12% 57%	7650
	21st to end	Day	1 1 1 3 2 3 4 4 7% 9% 64%	8304
August	1st to 10th	Day	1 1 1 3 3 3 4 4 6% 9% 66%	7549
	11th to 20th	Day	1 2 1 4 3 3 4 3 6% 8% 64%	7565
	21st to end	Day	2 3 1 4 3 4 5% 5% 9% 12% 52%	7903
September	1st to 10th	Day	3 2 1 3 3 4 3 3 5% 7% 65%	2506
	11th to 20th	Day	1 2 1 3 2 3 4 3 4 7% 69%	2310
	21st to end	Day	3 1 1 3 3 2 3 3 3 6% 72%	2289
October	1st to 10th	Day	2 2 1 2 2 2 2 2 2 4 79%	3303
	11th to 20th	Day	6% 4 2 4 2 2 3 2 5% 7% 61%	3250
	21st to end	Day	3 3 1 3 2 3 3 3 4 6% 71%	3548
November	1st to 10th	Day	2 4 1 3 3 2 2 2 4 6% 71%	2059
	11th to 20th	Day	2 3 1 4 2 3 3 3 4 6% 69%	1900
	21st to end	Day	3 4 1 5% 4 4 3 3 5% 7% 60%	1690
December	1st to 10th	Day	2 5% 2 4 3 4 4 5% 8% 11% 54%	2700
	11th to 20th	Day	2 4 2 5% 5% 6% 6% 5% 8% 12% 44%	3106
	21st to end	Day	3 7% 3 7% 5% 6% 6% 5% 7% 9% 41%	4539
January	1st to 10th	Night	3 9% 4 8% 5% 5% 5% 4 6% 9% 41%	7605
	11th to 20th	Night	1 3 1 4 3 4 4 3 5% 10% 61%	7650
	21st to end	Night	3 7% 3 6% 5% 4 5% 3 5% 9% 50%	8370
February	1st to 10th	Night	2 4 2 7% 5% 5% 6% 4 7% 10% 49%	2730
	11th to 20th	Night	3 6% 3 8% 6% 5% 6% 5% 7% 9% 44%	2662
	21st to end	Night	2 6% 2 5% 4 4 6% 5% 7% 9% 49%	1999
March	1st to 10th	Night	2 5% 2 6% 4 4 4 4 6% 7% 54%	5050
	11th to 20th	Night	4 8% 3 6% 4 4 5% 4 6% 8% 47%	5110
	21st to end	Night	2 4 2 6% 5% 5% 6% 5% 7% 8% 51%	5610
April	1st to 10th	Night	3 4 2 5% 4 4 4 4 6% 8% 55%	2213
	11th to 20th	Night	3 4 2 6% 4 4 3 4 6% 8% 55%	2077
	21st to end	Night	3 3 2 3 3 4 4 5% 6% 8% 57%	1952
May	1st to 10th	Night	3 4 2 5% 3 4 4 3 5% 7% 60%	5321
	11th to 20th	Night	3 4 2 5% 3 4 4 4 6% 7% 59%	5296
	21st to end	Night	2 3 1 3 3 3 3 3 5% 8% 66%	5837
June	1st to 10th	Night	2 2 1 3 3 3 3 4 5% 7% 67%	1784
	11th to 20th	Night	2 3 1 3 2 3 4 2 5% 7% 69%	1680
	21st to end	Night	1 1 1 3 3 3 3 4 4 6% 70%	1876
July	1st to 10th	Night	1 1 3 2 3 4 3 5% 7% 72%	5340
	11th to 20th	Night	2 3 1 6% 5% 5% 6% 6% 9% 11% 47%	5340
	21st to end	Night	1 2 1 5% 4 5% 6% 4 7% 10% 55%	5805
August	1st to 10th	Night	1 2 1 4 4 4 5% 5% 7% 9% 58%	5273
	11th to 20th	Night	1 2 1 4 3 4 4 4 7% 10% 61%	5291
	21st to end	Night	2 3 2 5% 4 5% 6% 5% 8% 12% 48%	6311
September	1st to 10th	Night	3 3 1 3 3 3 4 3 6% 7% 65%	2110
	11th to 20th	Night	2 2 1 4 3 3 3 3 4 8% 67%	2310
	21st to end	Night	4 2 1 3 2 2 3 3 4 5% 71%	2288
October	1st to 10th	Night	2 1 1 3 2 2 2 2 4 5% 75%	3887
	11th to 20th	Night	4 4 2 5% 4 4 4 3 5% 7% 58%	3898
	21st to end	Night	3 3 1 3 2 3 4 3 4 7% 66%	4252
November	1st to 10th	Night	2 3 1 3 3 3 4 3 4 6% 69%	2460
	11th to 20th	Night	2 4 1 3 3 2 3 3 4 7% 68%	2714
	21st to end	Night	4 5% 2 4 3 3 4 4 5% 7% 59%	2904
December	1st to 10th	Night	2 4 1 3 2 2 3 4 9% 14% 55%	4710
	11th to 20th	Night	2 4 2 5% 4 4 4 4 8% 14% 49%	5321
	21st to end	Night	4 6% 3 6% 4 5% 6% 5% 7% 13% 41%	6723

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	34% 5% 17% 31% 12% 1	5321
	11th to 20th	Day	19% 4 13% 32% 24% 8%	5340
	21st to end	Day	26% 4 10% 30% 26% 4	5844
February	1st to 10th	Day	30% 6% 16% 25% 19% 5%	1890
	11th to 20th	Day	31% 4 11% 25% 23% 5%	1854
	21st to end	Day	26% 5% 8% 26% 27% 7%	1801
March	1st to 10th	Day	22% 5% 5% 24% 32% 12%	5064
	11th to 20th	Day	35% 6% 8% 22% 21% 8%	5110
	21st to end	Day	30% 5% 9% 28% 24% 5%	5607
April	1st to 10th	Day	23% 4 7% 21% 30% 16%	2405
	11th to 20th	Day	22% 4 8% 23% 28% 15%	2494
	21st to end	Day	19% 5% 7% 21% 36% 13%	2664
May	1st to 10th	Day	17% 5% 7% 19% 37% 15%	7626
	11th to 20th	Day	16% 4 5% 17% 32% 28%	7599
	21st to end	Day	14% 3 4 13% 40% 25%	8371
June	1st to 10th	Day	13% 3 6% 12% 31% 35%	2824
	11th to 20th	Day	11% 3 4 8% 21% 53%	2939
	21st to end	Day	11% 3 5% 8% 21% 53%	2731
July	1st to 10th	Day	10% 3 4 5% 9% 70%	7586
	11th to 20th	Day	17% 5% 8% 18% 23% 28%	7581
	21st to end	Day	15% 5% 8% 21% 21% 31%	8120
August	1st to 10th	Day	18% 5% 8% 20% 16% 33%	5978
	11th to 20th	Day	20% 4 11% 20% 24% 20%	5964
	21st to end	Day	20% 5% 9% 25% 24% 18%	6194
September	1st to 10th	Day	18% 3 8% 13% 24% 33%	2506
	11th to 20th	Day	15% 5% 7% 18% 21% 33%	2310
	21st to end	Day	15% 4 5% 13% 34% 29%	2289
October	1st to 10th	Day	12% 3 4 14% 26% 41%	3303
	11th to 20th	Day	22% 3 3 20% 38% 14%	3250
	21st to end	Day	14% 3 6% 31% 40% 7%	3548
November	1st to 10th	Day	16% 2 8% 29% 35% 10%	2059
	11th to 20th	Day	17% 4 8% 33% 34% 4	1900
	21st to end	Day	22% 5% 11% 32% 25% 4	1690
December	1st to 10th	Day	21% 5% 19% 33% 19% 3	2700
	11th to 20th	Day	26% 6% 22% 34% 12%	3104
	21st to end	Day	34% 5% 15% 23% 20% 3	4539
January	1st to 10th	Night	36% 4 14% 30% 14% 2	7605
	11th to 20th	Night	17% 4 14% 31% 30% 6%	7650
	21st to end	Night	29% 4 10% 25% 28% 6%	8370
February	1st to 10th	Night	27% 4 14% 27% 21% 6%	2730
	11th to 20th	Night	30% 5% 9% 26% 24% 6%	2663
	21st to end	Night	26% 5% 10% 26% 26% 7%	1999
March	1st to 10th	Night	24% 6% 5% 20% 28% 16%	5050
	11th to 20th	Night	31% 5% 7% 23% 24% 10%	5110
	21st to end	Night	26% 6% 9% 29% 28% 4	5610
April	1st to 10th	Night	26% 4 7% 18% 29% 16%	2213
	11th to 20th	Night	25% 4 6% 18% 29% 17%	2077
	21st to end	Night	21% 6% 7% 17% 36% 13%	1952
May	1st to 10th	Night	22% 3 7% 15% 34% 19%	5319
	11th to 20th	Night	22% 5% 4 14% 30% 25%	5297
	21st to end	Night	15% 4 4 16% 36% 25%	5838
June	1st to 10th	Night	15% 3 4 12% 30% 35%	1784
	11th to 20th	Night	15% 3 5% 9% 16% 51%	1680
	21st to end	Night	14% 3 4 8% 19% 52%	1876
July	1st to 10th	Night	11% 3 4 7% 9% 66%	5295
	11th to 20th	Night	24% 5% 7% 16% 18% 29%	5286
	21st to end	Night	22% 5% 7% 19% 18% 29%	5677
August	1st to 10th	Night	25% 5% 8% 16% 12% 35%	4168
	11th to 20th	Night	21% 4 13% 19% 21% 23%	4168
	21st to end	Night	20% 5% 10% 23% 22% 20%	4951
September	1st to 10th	Night	18% 4 7% 13% 21% 37%	2110
	11th to 20th	Night	16% 4 9% 18% 21% 33%	2310
	21st to end	Night	16% 3 5% 13% 30% 32%	2288
October	1st to 10th	Night	12% 3 4 13% 23% 45%	3887
	11th to 20th	Night	25% 3 5% 14% 37% 16%	3898
	21st to end	Night	18% 2 4 27% 37% 11%	4252
November	1st to 10th	Night	17% 3 7% 20% 37% 15%	2460
	11th to 20th	Night	17% 3 8% 28% 38% 5%	2714
	21st to end	Night	23% 4 8% 24% 33% 8%	2904
December	1st to 10th	Night	17% 3 12% 45% 20% 4	4710
	11th to 20th	Night	23% 4 15% 42% 15%	5322
	21st to end	Night	29% 5% 16% 28% 19% 3	6723

Seeing (when cloud cover <= 80%)
Color Meanings: Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	10% 10% 24% 36% 16% 5%	330
	11th to 20th	Day	8% 7% 21% 40% 22% 3	330
	21st to end	Day	4 6% 18% 45% 23% 3	363
February	1st to 10th	Day	7% 10% 32% 35% 13% 4	330
	11th to 20th	Day	15% 7% 30% 33% 12% 2	330
	21st to end	Day	11% 17% 23% 32% 15% 2	441
March	1st to 10th	Day	10% 16% 29% 28% 15% 2	540
	11th to 20th	Day	11% 17% 28% 29% 12% 4	540
	21st to end	Day	13% 22% 29% 24% 9% 2	594
April	1st to 10th	Day	9% 16% 28% 27% 14% 6%	540
	11th to 20th	Day	13% 20% 30% 23% 10% 3	532
	21st to end	Day	9% 20% 31% 25% 13% 2	540
May	1st to 10th	Day	8% 16% 34% 27% 12% 3	543
	11th to 20th	Day	5% 14% 32% 26% 18% 5%	568
	21st to end	Day	7% 16% 27% 27% 17% 6%	617
June	1st to 10th	Day	4 9% 27% 34% 20% 7%	664
	11th to 20th	Day	4 10% 26% 35% 20% 5%	779
	21st to end	Day	4 11% 32% 31% 18% 4	571
July	1st to 10th	Day	3 4 25% 35% 27% 7%	566
	11th to 20th	Day	3 2 15% 31% 34% 14%	564
	21st to end	Day	3 2 12% 36% 34% 13%	619
August	1st to 10th	Day	5% 4 20% 35% 28% 10%	567
	11th to 20th	Day	3 4 18% 34% 29% 12%	557
	21st to end	Day	4 3 19% 32% 33% 9%	627
September	1st to 10th	Day	3 6% 19% 31% 29% 12%	570
	11th to 20th	Day	4 11% 27% 29% 22% 7%	570
	21st to end	Day	5% 12% 20% 28% 25% 10%	563
October	1st to 10th	Day	9% 9% 19% 22% 29% 11%	350
	11th to 20th	Day	11% 12% 17% 28% 26% 7%	330
	21st to end	Day	8% 12% 17% 34% 25% 5%	363
November	1st to 10th	Day	5% 16% 20% 28% 25% 5%	330
	11th to 20th	Day	5% 6% 22% 36% 21% 8%	330
	21st to end	Day	8% 5% 23% 35% 24% 5%	330
December	1st to 10th	Day	6% 10% 21% 35% 23% 5%	330
	11th to 20th	Day	5% 6% 22% 36% 25% 6%	330
	21st to end	Day	14% 9% 23% 37% 15% 2	363
January	1st to 10th	Night	7% 6% 16% 41% 25% 5%	840
	11th to 20th	Night	5% 4 17% 42% 28% 3	840
	21st to end	Night	7% 3 18% 48% 21% 3	924
February	1st to 10th	Night	6% 6% 23% 43% 19% 3	840
	11th to 20th	Night	6% 7% 26% 43% 17% 2	824
	21st to end	Night	6% 7% 26% 45% 15% 1	692
March	1st to 10th	Night	5% 10% 25% 40% 18% 1	840
	11th to 20th	Night	6% 5% 24% 39% 23% 3	840
	21st to end	Night	5% 11% 27% 39% 16% 2	924
April	1st to 10th	Night	7% 11% 30% 36% 15% 1	743
	11th to 20th	Night	7% 12% 31% 35% 14% 1	623
	21st to end	Night	6% 14% 27% 32% 19% 3	630
May	1st to 10th	Night	5% 8% 27% 42% 16% 2	630
	11th to 20th	Night	4 6% 21% 43% 22% 4	621
	21st to end	Night	4 11% 23% 36% 22% 4	683
June	1st to 10th	Night	3 5% 20% 41% 29% 2	630
	11th to 20th	Night	3 6% 24% 42% 23% 3	630
	21st to end	Night	2 4 18% 47% 26% 4	630
July	1st to 10th	Night	2 1 17% 36% 40% 5%	615
	11th to 20th	Night	3 1 9% 35% 46% 6%	612
	21st to end	Night	3 2 7% 33% 49% 6%	690
August	1st to 10th	Night	3 1 12% 36% 42% 5%	627
	11th to 20th	Night	2 2 12% 42% 36% 6%	624
	21st to end	Night	4 2 11% 40% 37% 7%	693
September	1st to 10th	Night	5% 2 10% 42% 36% 5%	640
	11th to 20th	Night	3 4 14% 40% 30% 8%	840
	21st to end	Night	5% 4 14% 37% 32% 8%	832
October	1st to 10th	Night	6% 5% 15% 43% 27% 4	800
	11th to 20th	Night	4 4 19% 42% 25% 6%	800
	21st to end	Night	6% 6% 18% 34% 30% 5%	880
November	1st to 10th	Night	4 5% 20% 38% 28% 5%	820
	11th to 20th	Night	4 5% 18% 43% 26% 5%	840
	21st to end	Night	8% 6% 17% 38% 26% 5%	1014
December	1st to 10th	Night	7% 5% 14% 49% 21% 4	1050
	11th to 20th	Night	7% 6% 20% 40% 25% 2	1050
	21st to end	Night	10% 7% 17% 43% 20% 3	971

Page generated at 2026-09-26 02:18:45. Version ac07

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