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 2025-05-26.

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 4 2 4 4 4 4 4 6% 8% 58%	118043
	Night	3 4 2 5% 4 4 5% 4 6% 9% 55%	120160
Transparency	Day	21% 5% 9% 21% 25% 19%	117808
	Night	23% 5% 9% 23% 25% 16%	119984
Seeing	Day	7% 11% 24% 31% 21% 6%	15560
	Night	5% 6% 19% 40% 26% 4	26054

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 7% 5% 6% 7% 6% 7% 10% 43%	4098
	11th to 20th	Day	2 4 2 6% 4 6% 5% 4 8% 10% 50%	4100
	21st to end	Day	3 6% 2 6% 5% 5% 5% 4 7% 9% 48%	4510
February	1st to 10th	Day	2 5% 2 9% 7% 5% 5% 5% 7% 10% 43%	1800
	11th to 20th	Day	4 6% 3 6% 6% 5% 5% 4 7% 10% 45%	1755
	21st to end	Day	3 6% 2 6% 5% 4 5% 4 6% 10% 49%	1717
March	1st to 10th	Day	1 4 2 5% 4 4 5% 4 6% 7% 56%	4954
	11th to 20th	Day	3 10% 3 7% 5% 5% 5% 4 6% 7% 43%	5000
	21st to end	Day	3 6% 3 7% 5% 4 5% 4 6% 8% 47%	5486
April	1st to 10th	Day	3 4 2 4 4 5% 5% 3 6% 7% 58%	2290
	11th to 20th	Day	2 4 1 5% 4 5% 4 4 6% 9% 56%	2371
	21st to end	Day	2 3 1 4 4 4 4 4 6% 9% 59%	2537
May	1st to 10th	Day	2 3 1 4 3 4 5% 4 6% 9% 58%	4240
	11th to 20th	Day	1 2 1 4 2 3 4 4 6% 7% 66%	4201
	21st to end	Day	2 3 1 4 3 4 4 3 5% 7% 65%	4544
June	1st to 10th	Day	2 2 1 2 2 2 3 3 6% 7% 70%	2555
	11th to 20th	Day	1 2 1 3 2 2 3 3 4 6% 75%	2659
	21st to end	Day	1 2 1 2 2 3 3 3 5% 7% 72%	2471
July	1st to 10th	Day	1 2 1 3 2 2 2 2 4 5% 76%	4110
	11th to 20th	Day	1 2 1 2 3 4 5% 6% 10% 13% 53%	4110
	21st to end	Day	1 2 1 3 3 4 4 4 7% 9% 61%	4454
August	1st to 10th	Day	2 2 1 4 4 5% 6% 5% 9% 11% 50%	4092
	11th to 20th	Day	1 2 1 4 3 4 5% 4 6% 8% 61%	4028
	21st to end	Day	2 2 1 3 3 4 5% 5% 6% 9% 60%	4257
September	1st to 10th	Day	3 2 1 3 3 4 3 3 5% 7% 65%	2268
	11th to 20th	Day	1 2 1 3 2 2 3 3 4 7% 70%	2090
	21st to end	Day	3 2 1 3 3 2 2 2 3 6% 74%	2090
October	1st to 10th	Day	2 2 1 2 2 2 2 2 2 4 79%	3202
	11th to 20th	Day	6% 4 2 4 3 2 3 2 5% 8% 61%	3150
	21st to end	Day	3 3 1 2 2 3 3 3 4 6% 71%	3438
November	1st to 10th	Day	3 4 1 3 3 2 2 2 4 6% 70%	1959
	11th to 20th	Day	1 3 1 4 2 3 2 3 4 6% 71%	1810
	21st to end	Day	3 4 1 5% 4 4 3 3 5% 7% 60%	1610
December	1st to 10th	Day	2 5% 2 4 3 4 4 5% 8% 11% 53%	2620
	11th to 20th	Day	2 4 2 5% 5% 6% 6% 5% 8% 12% 43%	3026
	21st to end	Day	3 7% 3 7% 5% 6% 6% 5% 7% 9% 41%	4441
January	1st to 10th	Night	2 8% 4 7% 5% 5% 5% 4 6% 10% 44%	5867
	11th to 20th	Night	1 3 2 5% 4 5% 5% 4 6% 11% 53%	5880
	21st to end	Night	3 7% 3 7% 5% 5% 5% 4 6% 10% 45%	6468
February	1st to 10th	Night	2 5% 2 7% 5% 5% 6% 4 7% 10% 48%	2600
	11th to 20th	Night	3 6% 3 7% 6% 5% 6% 5% 7% 9% 44%	2532
	21st to end	Night	3 6% 2 5% 5% 4 6% 6% 7% 9% 47%	1907
March	1st to 10th	Night	2 5% 2 6% 4 4 4 4 6% 7% 54%	4940
	11th to 20th	Night	4 8% 3 7% 4 4 5% 4 6% 8% 46%	5000
	21st to end	Night	2 4 2 6% 5% 5% 6% 5% 7% 8% 51%	5489
April	1st to 10th	Night	3 4 2 5% 4 4 4 4 7% 8% 55%	2108
	11th to 20th	Night	3 4 2 6% 4 4 3 5% 6% 8% 54%	1977
	21st to end	Night	3 3 2 3 3 4 4 5% 6% 8% 57%	1859
May	1st to 10th	Night	2 4 2 5% 4 4 4 4 5% 8% 59%	2950
	11th to 20th	Night	2 3 1 5% 3 4 5% 6% 7% 9% 55%	2924
	21st to end	Night	2 3 1 4 3 3 3 3 5% 8% 63%	3159
June	1st to 10th	Night	2 2 1 3 3 3 3 4 5% 7% 68%	1614
	11th to 20th	Night	2 3 1 3 3 3 4 2 5% 7% 68%	1520
	21st to end	Night	1 2 1 4 3 3 3 4 5% 7% 68%	1697
July	1st to 10th	Night	1 1 1 3 2 3 4 3 5% 7% 71%	2860
	11th to 20th	Night	1 3 1 6% 5% 6% 6% 6% 10% 12% 44%	2860
	21st to end	Night	2 3 2 5% 4 5% 7% 4 7% 9% 51%	3109
August	1st to 10th	Night	2 3 1 6% 6% 6% 7% 6% 10% 12% 41%	2847
	11th to 20th	Night	2 2 2 5% 4 5% 5% 5% 8% 9% 55%	2811
	21st to end	Night	2 3 1 4 3 4 5% 4 6% 8% 60%	3408
September	1st to 10th	Night	3 3 1 3 3 3 4 3 6% 7% 65%	1909
	11th to 20th	Night	2 2 1 4 3 3 3 3 4 8% 67%	2090
	21st to end	Night	4 2 1 3 2 2 3 2 3 5% 73%	2090
October	1st to 10th	Night	2 1 1 3 2 2 2 2 4 5% 75%	3768
	11th to 20th	Night	4 4 2 5% 4 4 4 3 5% 7% 58%	3778
	21st to end	Night	3 3 1 3 2 3 4 3 4 7% 66%	4120
November	1st to 10th	Night	2 4 1 3 3 3 4 3 4 5% 68%	2340
	11th to 20th	Night	2 3 1 3 2 2 3 3 4 7% 69%	2585
	21st to end	Night	4 5% 2 4 3 3 4 4 5% 7% 60%	2765
December	1st to 10th	Night	2 4 1 3 2 2 3 4 9% 14% 55%	4570
	11th to 20th	Night	2 4 2 6% 4 4 4 4 8% 14% 48%	5181
	21st to end	Night	4 6% 3 6% 4 5% 6% 5% 7% 13% 41%	6578

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	31% 6% 15% 33% 13% 2	4099
	11th to 20th	Day	25% 5% 13% 31% 18% 10%	4100
	21st to end	Day	28% 5% 12% 27% 25% 4	4510
February	1st to 10th	Day	31% 6% 17% 24% 18% 5%	1800
	11th to 20th	Day	30% 4 12% 25% 23% 5%	1764
	21st to end	Day	27% 5% 8% 24% 28% 7%	1717
March	1st to 10th	Day	22% 5% 5% 24% 32% 12%	4954
	11th to 20th	Day	36% 7% 8% 22% 21% 7%	5000
	21st to end	Day	30% 6% 9% 28% 23% 4	5486
April	1st to 10th	Day	23% 4 7% 22% 29% 15%	2290
	11th to 20th	Day	22% 4 8% 23% 27% 16%	2374
	21st to end	Day	19% 5% 7% 21% 35% 12%	2537
May	1st to 10th	Day	18% 7% 7% 16% 34% 18%	4240
	11th to 20th	Day	15% 5% 8% 18% 34% 22%	4204
	21st to end	Day	16% 4 6% 14% 35% 24%	4544
June	1st to 10th	Day	12% 3 6% 13% 32% 35%	2555
	11th to 20th	Day	11% 3 4 8% 22% 51%	2659
	21st to end	Day	12% 3 5% 9% 22% 50%	2471
July	1st to 10th	Day	11% 4 5% 7% 9% 65%	4046
	11th to 20th	Day	16% 7% 7% 17% 27% 25%	4041
	21st to end	Day	18% 6% 8% 16% 19% 32%	4314
August	1st to 10th	Day	23% 7% 11% 26% 16% 18%	4078
	11th to 20th	Day	20% 5% 11% 16% 21% 27%	4067
	21st to end	Day	19% 6% 8% 16% 27% 25%	4256
September	1st to 10th	Day	18% 4 8% 12% 24% 34%	2268
	11th to 20th	Day	14% 6% 8% 16% 21% 36%	2090
	21st to end	Day	13% 4 4 13% 35% 30%	2090
October	1st to 10th	Day	12% 3 4 14% 26% 41%	3202
	11th to 20th	Day	23% 3 3 20% 38% 13%	3150
	21st to end	Day	14% 3 6% 31% 40% 7%	3438
November	1st to 10th	Day	16% 2 9% 28% 34% 10%	1959
	11th to 20th	Day	16% 4 8% 33% 35% 4	1810
	21st to end	Day	22% 5% 10% 32% 26% 5%	1610
December	1st to 10th	Day	21% 5% 19% 33% 19% 3	2620
	11th to 20th	Day	27% 6% 22% 33% 12%	3024
	21st to end	Day	34% 5% 16% 23% 20% 3	4441
January	1st to 10th	Night	31% 5% 14% 30% 17% 2	5867
	11th to 20th	Night	22% 5% 14% 28% 27% 5%	5880
	21st to end	Night	30% 5% 10% 25% 25% 5%	6468
February	1st to 10th	Night	28% 5% 15% 27% 20% 6%	2600
	11th to 20th	Night	29% 5% 10% 26% 24% 6%	2533
	21st to end	Night	28% 5% 9% 25% 26% 8%	1907
March	1st to 10th	Night	25% 6% 5% 20% 28% 16%	4940
	11th to 20th	Night	32% 5% 7% 23% 24% 9%	5000
	21st to end	Night	26% 6% 9% 29% 27% 3	5489
April	1st to 10th	Night	25% 4 7% 19% 29% 16%	2108
	11th to 20th	Night	26% 4 7% 18% 28% 18%	1977
	21st to end	Night	21% 6% 7% 18% 36% 12%	1859
May	1st to 10th	Night	21% 4 9% 15% 34% 18%	2950
	11th to 20th	Night	19% 6% 7% 18% 32% 17%	2925
	21st to end	Night	16% 5% 6% 15% 33% 24%	3159
June	1st to 10th	Night	14% 4 4 13% 32% 34%	1614
	11th to 20th	Night	16% 3 6% 9% 17% 49%	1520
	21st to end	Night	14% 4 4 9% 21% 48%	1697
July	1st to 10th	Night	12% 4 6% 9% 8% 61%	2815
	11th to 20th	Night	23% 7% 7% 16% 23% 23%	2806
	21st to end	Night	25% 6% 9% 15% 18% 28%	3011
August	1st to 10th	Night	30% 6% 12% 20% 14% 18%	2838
	11th to 20th	Night	23% 4 11% 17% 15% 30%	2838
	21st to end	Night	20% 5% 8% 14% 25% 28%	3408
September	1st to 10th	Night	18% 5% 7% 13% 20% 38%	1909
	11th to 20th	Night	16% 5% 8% 17% 20% 35%	2090
	21st to end	Night	15% 3 5% 13% 30% 34%	2090
October	1st to 10th	Night	12% 4 4 13% 22% 46%	3768
	11th to 20th	Night	25% 3 5% 14% 37% 16%	3778
	21st to end	Night	18% 2 4 28% 37% 11%	4120
November	1st to 10th	Night	18% 4 7% 21% 36% 15%	2340
	11th to 20th	Night	17% 3 7% 28% 39% 5%	2585
	21st to end	Night	23% 4 8% 23% 35% 8%	2765
December	1st to 10th	Night	17% 3 12% 45% 20% 4	4570
	11th to 20th	Night	24% 5% 15% 42% 14%	5182
	21st to end	Night	29% 6% 16% 28% 18% 3	6578

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	9% 10% 24% 35% 16% 6%	300
	11th to 20th	Day	8% 8% 22% 37% 22% 3	300
	21st to end	Day	4 6% 19% 43% 24% 3	330
February	1st to 10th	Day	8% 10% 33% 34% 12% 2	300
	11th to 20th	Day	12% 7% 31% 34% 13% 2	300
	21st to end	Day	11% 18% 24% 31% 14% 2	409
March	1st to 10th	Day	10% 16% 29% 28% 15% 2	500
	11th to 20th	Day	11% 17% 28% 28% 12% 4	500
	21st to end	Day	13% 22% 30% 24% 9% 1	550
April	1st to 10th	Day	9% 18% 28% 27% 14% 5%	500
	11th to 20th	Day	12% 20% 32% 24% 10% 2	492
	21st to end	Day	8% 20% 31% 25% 14% 2	500
May	1st to 10th	Day	9% 16% 34% 26% 12% 3	503
	11th to 20th	Day	5% 15% 32% 27% 17% 5%	528
	21st to end	Day	7% 17% 29% 26% 16% 5%	550
June	1st to 10th	Day	3 9% 27% 35% 19% 6%	575
	11th to 20th	Day	4 11% 26% 34% 21% 5%	679
	21st to end	Day	3 10% 32% 33% 19% 4	491
July	1st to 10th	Day	3 3 23% 38% 26% 7%	486
	11th to 20th	Day	3 2 16% 32% 34% 13%	484
	21st to end	Day	3 2 12% 36% 36% 12%	531
August	1st to 10th	Day	6% 2 18% 38% 27% 9%	487
	11th to 20th	Day	3 5% 18% 35% 28% 11%	477
	21st to end	Day	4 4 20% 33% 32% 8%	539
September	1st to 10th	Day	3 4 20% 31% 30% 13%	490
	11th to 20th	Day	4 11% 25% 30% 22% 8%	490
	21st to end	Day	4 12% 20% 28% 25% 10%	490
October	1st to 10th	Day	9% 9% 17% 22% 30% 12%	319
	11th to 20th	Day	10% 12% 15% 27% 28% 7%	300
	21st to end	Day	8% 13% 16% 35% 25% 3	330
November	1st to 10th	Day	5% 18% 20% 29% 24% 4	300
	11th to 20th	Day	4 7% 24% 37% 21% 7%	300
	21st to end	Day	8% 6% 25% 33% 25% 4	300
December	1st to 10th	Day	6% 11% 21% 33% 24% 5%	300
	11th to 20th	Day	5% 7% 22% 38% 24% 5%	300
	21st to end	Day	13% 8% 22% 39% 15% 2	330
January	1st to 10th	Night	6% 6% 15% 41% 26% 6%	800
	11th to 20th	Night	6% 4 17% 42% 28% 3	800
	21st to end	Night	7% 3 17% 48% 21% 3	880
February	1st to 10th	Night	6% 6% 23% 42% 19% 3	800
	11th to 20th	Night	5% 7% 26% 43% 17% 2	784
	21st to end	Night	6% 8% 25% 45% 15% 1	660
March	1st to 10th	Night	6% 11% 24% 40% 19% 2	800
	11th to 20th	Night	7% 6% 23% 38% 24% 3	800
	21st to end	Night	5% 11% 26% 39% 16% 2	880
April	1st to 10th	Night	7% 11% 31% 36% 15% 1	708
	11th to 20th	Night	7% 12% 31% 34% 15% 1	593
	21st to end	Night	6% 13% 27% 32% 19% 3	600
May	1st to 10th	Night	5% 9% 26% 42% 17% 2	600
	11th to 20th	Night	4 6% 21% 43% 22% 4	591
	21st to end	Night	4 11% 23% 36% 22% 4	634
June	1st to 10th	Night	3 5% 18% 41% 31% 2	570
	11th to 20th	Night	3 6% 23% 41% 24% 3	570
	21st to end	Night	1 2 18% 47% 28% 4	570
July	1st to 10th	Night	2 1 16% 33% 43% 6%	555
	11th to 20th	Night	3 1 10% 34% 47% 6%	552
	21st to end	Night	3 2 6% 32% 51% 7%	624
August	1st to 10th	Night	4 1 10% 36% 44% 6%	567
	11th to 20th	Night	3 3 12% 40% 36% 6%	564
	21st to end	Night	4 1 11% 38% 37% 8%	627
September	1st to 10th	Night	6% 2 9% 39% 39% 6%	579
	11th to 20th	Night	3 4 14% 38% 32% 9%	760
	21st to end	Night	4 4 14% 36% 33% 8%	760
October	1st to 10th	Night	6% 5% 15% 43% 28% 4	760
	11th to 20th	Night	4 4 18% 43% 26% 6%	760
	21st to end	Night	7% 5% 18% 34% 30% 6%	836
November	1st to 10th	Night	5% 5% 20% 37% 28% 5%	780
	11th to 20th	Night	5% 4 19% 42% 26% 5%	800
	21st to end	Night	8% 6% 17% 36% 27% 5%	965
December	1st to 10th	Night	7% 5% 14% 49% 22% 4	1000
	11th to 20th	Night	8% 6% 20% 40% 24% 2	1000
	21st to end	Night	11% 6% 16% 43% 20% 3	925

Page generated at 2025-05-23 07:20:58. Version ac07

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