Colorado Springs
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Colorado Springs clear sky chart from 2005-11-06 to 2025-09-04.

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	3 4 2 5% 4 4 4 4 7% 8% 55%	134722
	Night	3 4 2 4 3 3 4 3 5% 7% 61%	131448
Transparency	Day	22% 7% 11% 23% 24% 12%	129698
	Night	21% 7% 12% 24% 25% 11%	127479
Seeing	Day	6% 10% 31% 30% 18% 5%	16693
	Night	5% 5% 32% 40% 16% 2	26641

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	1 4 3 5% 3 3 2 3 5% 8% 64%	3638
	11th to 20th	Day	1 2 1 5% 4 6% 4 4 5% 8% 61%	3806
	21st to end	Day	2 5% 2 7% 4 4 3 2 4 6% 62%	4510
February	1st to 10th	Day	1 5% 2 5% 4 4 3 3 5% 7% 60%	1820
	11th to 20th	Day	1 3 1 5% 4 3 4 3 7% 10% 59%	1949
	21st to end	Day	1 5% 2 8% 3 3 4 3 5% 6% 60%	1650
March	1st to 10th	Day	1 5% 2 5% 3 3 3 3 5% 7% 64%	4500
	11th to 20th	Day	3 9% 2 6% 4 4 4 3 6% 7% 52%	4904
	21st to end	Day	1 5% 2 5% 4 3 5% 4 6% 9% 56%	5837
April	1st to 10th	Day	2 6% 2 4 4 3 4 5% 7% 8% 56%	2400
	11th to 20th	Day	6% 6% 3 6% 3 4 5% 4 6% 7% 50%	2371
	21st to end	Day	5% 7% 2 6% 4 5% 4 4 7% 9% 48%	2400
May	1st to 10th	Day	11% 7% 2 4 3 3 4 3 6% 8% 49%	5706
	11th to 20th	Day	5% 5% 2 5% 3 4 4 4 6% 9% 53%	6138
	21st to end	Day	6% 4 1 4 3 4 5% 5% 8% 9% 49%	6925
June	1st to 10th	Day	4 4 2 5% 4 5% 6% 5% 9% 10% 47%	2800
	11th to 20th	Day	4 3 1 4 3 4 6% 6% 8% 8% 55%	2800
	21st to end	Day	3 4 1 5% 4 5% 6% 6% 9% 9% 48%	2800
July	1st to 10th	Day	2 2 1 3 3 4 6% 5% 8% 11% 54%	6339
	11th to 20th	Day	3 3 2 5% 5% 7% 7% 6% 9% 9% 44%	6340
	21st to end	Day	4 4 2 5% 5% 6% 6% 6% 8% 9% 46%	6724
August	1st to 10th	Day	7% 4 1 6% 5% 5% 6% 6% 9% 10% 41%	5677
	11th to 20th	Day	2 2 1 3 3 5% 6% 6% 9% 11% 50%	5366
	21st to end	Day	7% 4 2 4 4 5% 6% 5% 8% 10% 45%	5981
September	1st to 10th	Day	4 3 1 4 3 4 5% 5% 7% 9% 55%	2317
	11th to 20th	Day	5% 3 1 4 3 4 4 4 6% 8% 59%	2244
	21st to end	Day	4 3 1 4 3 3 4 3 5% 6% 65%	2090
October	1st to 10th	Day	3 2 1 3 2 2 3 2 3 5% 74%	3237
	11th to 20th	Day	4 3 2 5% 3 2 4 2 5% 7% 63%	3150
	21st to end	Day	3 3 1 3 2 2 2 2 4 5% 75%	3325
November	1st to 10th	Day	2 3 1 4 2 3 3 2 5% 8% 67%	1763
	11th to 20th	Day	1 3 1 3 2 3 3 3 5% 7% 69%	1800
	21st to end	Day	1 4 2 4 4 3 3 3 4 7% 65%	1765
December	1st to 10th	Day	1 4 2 3 2 2 3 1 4 5% 73%	2620
	11th to 20th	Day	1 3 1 3 2 2 2 2 3 7% 72%	3026
	21st to end	Day	1 3 2 4 3 3 4 3 6% 7% 63%	4004
January	1st to 10th	Night	1 5% 3 7% 3 3 4 3 5% 8% 59%	6327
	11th to 20th	Night	1 2 1 4 4 3 4 3 5% 8% 65%	6205
	21st to end	Night	1 3 1 5% 3 4 4 2 5% 6% 65%	6468
February	1st to 10th	Night	1 4 2 5% 4 4 4 3 5% 7% 60%	2579
	11th to 20th	Night	1 5% 3 6% 4 4 5% 4 6% 8% 55%	2338
	21st to end	Night	1 4 2 6% 4 3 3 2 4 5% 66%	1980
March	1st to 10th	Night	1 5% 2 5% 3 3 3 3 5% 6% 65%	5374
	11th to 20th	Night	4 8% 2 4 3 3 3 4 4 7% 58%	5088
	21st to end	Night	2 6% 2 5% 4 3 3 3 5% 7% 60%	5122
April	1st to 10th	Night	2 5% 1 4 3 4 4 3 4 7% 63%	2000
	11th to 20th	Night	6% 7% 2 5% 2 3 3 4 6% 7% 55%	1977
	21st to end	Night	6% 6% 2 5% 3 4 3 3 5% 8% 55%	2000
May	1st to 10th	Night	12% 6% 1 4 2 3 3 3 5% 6% 55%	4273
	11th to 20th	Night	5% 5% 2 4 3 4 4 3 6% 9% 55%	3761
	21st to end	Night	8% 4 2 5% 4 4 3 3 5% 7% 55%	3972
June	1st to 10th	Night	4 3 1 4 3 3 4 4 6% 9% 59%	1600
	11th to 20th	Night	3 3 1 3 2 4 4 4 6% 8% 64%	1600
	21st to end	Night	3 4 1 4 3 5% 6% 4 8% 7% 54%	1600
July	1st to 10th	Night	4 2 2 4 4 4 4 5% 7% 8% 58%	3640
	11th to 20th	Night	3 3 2 3 4 4 5% 5% 8% 11% 52%	3640
	21st to end	Night	4 4 2 6% 4 4 5% 4 8% 10% 51%	4145
August	1st to 10th	Night	6% 5% 1 5% 4 4 5% 4 6% 9% 50%	4135
	11th to 20th	Night	4 3 1 4 4 4 5% 4 8% 11% 52%	4483
	21st to end	Night	7% 5% 2 5% 3 4 5% 5% 8% 10% 46%	4993
September	1st to 10th	Night	4 4 1 5% 4 5% 5% 4 6% 8% 54%	1930
	11th to 20th	Night	6% 3 1 4 2 2 4 2 4 8% 65%	1934
	21st to end	Night	4 4 1 4 3 2 3 3 4 6% 66%	2090
October	1st to 10th	Night	4 3 1 2 2 2 2 2 3 4 75%	3726
	11th to 20th	Night	7% 3 1 4 2 2 2 3 4 6% 65%	3778
	21st to end	Night	2 3 2 3 2 2 3 2 4 5% 71%	4199
November	1st to 10th	Night	2 3 1 3 2 2 2 3 5% 8% 67%	2535
	11th to 20th	Night	1 2 1 4 3 2 2 3 4 6% 72%	2600
	21st to end	Night	2 5% 2 4 3 3 3 3 4 7% 66%	2631
December	1st to 10th	Night	2 2 3 2 2 2 2 3 6% 76%	4570
	11th to 20th	Night	1 3 1 3 3 3 3 3 5% 8% 68%	5181
	21st to end	Night	2 5% 2 5% 3 3 4 3 5% 7% 62%	6974

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	18% 5% 8% 32% 27% 10%	3639
	11th to 20th	Day	19% 8% 10% 22% 30% 11%	3806
	21st to end	Day	23% 5% 9% 25% 28% 11%	4510
February	1st to 10th	Day	23% 6% 11% 25% 23% 11%	1820
	11th to 20th	Day	20% 7% 10% 26% 29% 8%	1959
	21st to end	Day	24% 5% 8% 21% 24% 19%	1650
March	1st to 10th	Day	17% 5% 8% 16% 32% 22%	4500
	11th to 20th	Day	27% 6% 11% 22% 25% 8%	4904
	21st to end	Day	20% 8% 13% 37% 19% 3	5837
April	1st to 10th	Day	23% 8% 13% 24% 21% 12%	2400
	11th to 20th	Day	30% 7% 12% 22% 18% 12%	2374
	21st to end	Day	29% 7% 14% 25% 20% 5%	2400
May	1st to 10th	Day	31% 6% 12% 26% 16% 8%	5706
	11th to 20th	Day	25% 8% 12% 19% 23% 13%	6142
	21st to end	Day	24% 9% 16% 22% 20% 9%	6926
June	1st to 10th	Day	26% 9% 16% 23% 17% 10%	2800
	11th to 20th	Day	20% 8% 12% 17% 24% 19%	2800
	21st to end	Day	25% 10% 12% 19% 21% 13%	2800
July	1st to 10th	Day	18% 9% 12% 19% 26% 16%	6271
	11th to 20th	Day	27% 11% 14% 24% 15% 9%	6265
	21st to end	Day	28% 11% 14% 16% 16% 15%	6529
August	1st to 10th	Day	35% 12% 16% 21% 11% 5%	4128
	11th to 20th	Day	22% 12% 15% 19% 19% 13%	3882
	21st to end	Day	24% 10% 14% 20% 26% 6%	4311
September	1st to 10th	Day	22% 7% 11% 21% 24% 15%	2317
	11th to 20th	Day	21% 6% 10% 18% 28% 18%	2244
	21st to end	Day	20% 6% 7% 20% 33% 15%	2090
October	1st to 10th	Day	14% 4 7% 15% 37% 23%	3237
	11th to 20th	Day	21% 5% 9% 22% 32% 11%	3150
	21st to end	Day	14% 3 6% 21% 38% 18%	3325
November	1st to 10th	Day	16% 3 11% 22% 29% 18%	1763
	11th to 20th	Day	14% 4 8% 28% 33% 12%	1800
	21st to end	Day	20% 3 9% 21% 30% 17%	1765
December	1st to 10th	Day	14% 5% 9% 30% 33% 10%	2620
	11th to 20th	Day	15% 4 7% 31% 31% 13%	3024
	21st to end	Day	18% 6% 10% 26% 26% 12%	4004
January	1st to 10th	Night	24% 4 9% 31% 25% 7%	6327
	11th to 20th	Night	17% 7% 11% 25% 25% 16%	6205
	21st to end	Night	19% 7% 11% 25% 27% 11%	6468
February	1st to 10th	Night	23% 6% 10% 27% 24% 11%	2579
	11th to 20th	Night	26% 7% 10% 28% 22% 8%	2338
	21st to end	Night	20% 4 6% 25% 27% 17%	1980
March	1st to 10th	Night	19% 5% 8% 16% 38% 15%	5374
	11th to 20th	Night	25% 6% 11% 17% 27% 13%	5088
	21st to end	Night	22% 8% 13% 31% 23% 3	5122
April	1st to 10th	Night	21% 7% 12% 24% 25% 12%	2000
	11th to 20th	Night	28% 7% 11% 25% 19% 10%	1977
	21st to end	Night	28% 7% 14% 26% 19% 7%	2000
May	1st to 10th	Night	30% 7% 15% 29% 12% 8%	4270
	11th to 20th	Night	24% 9% 15% 24% 16% 13%	3762
	21st to end	Night	26% 12% 15% 23% 18% 7%	3972
June	1st to 10th	Night	22% 9% 20% 25% 14% 10%	1600
	11th to 20th	Night	17% 7% 15% 23% 20% 18%	1600
	21st to end	Night	25% 9% 11% 21% 23% 12%	1600
July	1st to 10th	Night	21% 10% 12% 19% 31% 6%	3600
	11th to 20th	Night	21% 12% 22% 26% 14% 5%	3592
	21st to end	Night	26% 10% 18% 19% 15% 12%	4028
August	1st to 10th	Night	35% 12% 19% 19% 9% 7%	3008
	11th to 20th	Night	25% 11% 19% 20% 19% 6%	3243
	21st to end	Night	23% 12% 18% 26% 17% 4	3597
September	1st to 10th	Night	26% 7% 11% 23% 22% 12%	1930
	11th to 20th	Night	19% 4 12% 22% 26% 17%	1934
	21st to end	Night	21% 5% 9% 22% 32% 12%	2090
October	1st to 10th	Night	14% 4 8% 21% 34% 18%	3726
	11th to 20th	Night	21% 6% 7% 28% 27% 11%	3778
	21st to end	Night	16% 4 8% 24% 32% 16%	4199
November	1st to 10th	Night	16% 3 11% 25% 28% 16%	2535
	11th to 20th	Night	15% 4 8% 28% 33% 12%	2600
	21st to end	Night	20% 3 11% 22% 30% 13%	2631
December	1st to 10th	Night	12% 4 9% 34% 32% 10%	4570
	11th to 20th	Night	15% 4 8% 27% 35% 10%	5182
	21st to end	Night	22% 5% 12% 21% 27% 12%	6974

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	5% 8% 33% 37% 14% 3	300
	11th to 20th	Day	4 12% 35% 36% 10% 2	300
	21st to end	Day	3 11% 37% 34% 13% 2	330
February	1st to 10th	Day	4 14% 49% 25% 6% 2	300
	11th to 20th	Day	3 15% 47% 25% 9% 1	300
	21st to end	Day	2 14% 50% 27% 7% 1	249
March	1st to 10th	Day	2 15% 39% 30% 11% 2	300
	11th to 20th	Day	8% 17% 42% 22% 9% 2	456
	21st to end	Day	10% 22% 40% 21% 5% 2	550
April	1st to 10th	Day	8% 19% 41% 23% 7% 1	500
	11th to 20th	Day	11% 24% 39% 20% 5% 2	492
	21st to end	Day	11% 20% 36% 25% 7% 2	500
May	1st to 10th	Day	14% 15% 34% 25% 9% 2	613
	11th to 20th	Day	11% 10% 30% 31% 15% 4	725
	21st to end	Day	7% 11% 32% 28% 17% 4	789
June	1st to 10th	Day	5% 8% 25% 32% 22% 6%	730
	11th to 20th	Day	5% 8% 30% 30% 22% 5%	730
	21st to end	Day	3 8% 28% 32% 22% 7%	730
July	1st to 10th	Day	5% 3 20% 30% 33% 8%	721
	11th to 20th	Day	3 3 16% 31% 35% 11%	718
	21st to end	Day	4 2 15% 30% 36% 13%	716
August	1st to 10th	Day	7% 3 21% 34% 28% 6%	527
	11th to 20th	Day	4 5% 22% 35% 23% 11%	517
	21st to end	Day	5% 4 23% 39% 19% 10%	583
September	1st to 10th	Day	6% 3 26% 36% 19% 9%	503
	11th to 20th	Day	4 7% 32% 29% 20% 8%	454
	21st to end	Day	8% 8% 19% 31% 26% 9%	300
October	1st to 10th	Day	6% 11% 21% 28% 24% 10%	300
	11th to 20th	Day	2 10% 34% 28% 21% 6%	300
	21st to end	Day	7% 10% 34% 30% 17% 3	330
November	1st to 10th	Day	5% 11% 36% 28% 16% 5%	300
	11th to 20th	Day	3 7% 38% 33% 15% 3	300
	21st to end	Day	3 12% 35% 32% 14% 4	300
December	1st to 10th	Day	2 10% 40% 31% 14% 4	300
	11th to 20th	Day	4 7% 39% 34% 14% 1	300
	21st to end	Day	2 12% 44% 33% 8% 2	330
January	1st to 10th	Night	3 5% 38% 38% 12% 3	1000
	11th to 20th	Night	3 6% 43% 34% 11% 2	943
	21st to end	Night	2 4 38% 44% 10% 1	880
February	1st to 10th	Night	3 6% 52% 33% 6% 1	800
	11th to 20th	Night	3 5% 49% 35% 8% 1	784
	21st to end	Night	2 5% 53% 34% 6%	660
March	1st to 10th	Night	3 6% 47% 35% 9% 1	800
	11th to 20th	Night	7% 5% 35% 41% 11% 1	800
	21st to end	Night	5% 7% 46% 34% 6% 1	720
April	1st to 10th	Night	7% 9% 44% 36% 5%	600
	11th to 20th	Night	12% 11% 34% 35% 7% 1	593
	21st to end	Night	10% 9% 34% 38% 9% 1	600
May	1st to 10th	Night	12% 8% 29% 39% 12% 1	600
	11th to 20th	Night	12% 5% 26% 41% 15% 2	591
	21st to end	Night	10% 6% 32% 35% 16% 2	650
June	1st to 10th	Night	6% 3 22% 43% 23% 3	600
	11th to 20th	Night	4 4 25% 49% 17% 1	600
	21st to end	Night	4 3 19% 47% 25% 2	600
July	1st to 10th	Night	6% 3 15% 41% 33% 3	585
	11th to 20th	Night	3 1 9% 43% 40% 4	582
	21st to end	Night	6% 1 11% 36% 42% 4	657
August	1st to 10th	Night	7% 3 11% 39% 37% 4	597
	11th to 20th	Night	5% 2 10% 45% 34% 3	594
	21st to end	Night	5% 1 10% 45% 34% 4	660
September	1st to 10th	Night	3 2 13% 47% 30% 4	579
	11th to 20th	Night	7% 2 16% 46% 24% 5%	570
	21st to end	Night	7% 3 20% 44% 22% 4	570
October	1st to 10th	Night	9% 4 24% 40% 19% 3	712
	11th to 20th	Night	4 4 31% 38% 19% 4	760
	21st to end	Night	5% 6% 31% 37% 18% 3	879
November	1st to 10th	Night	3 3 35% 41% 16% 2	975
	11th to 20th	Night	2 5% 37% 43% 10% 3	1000
	21st to end	Night	5% 6% 33% 42% 13% 2	1000
December	1st to 10th	Night	2 4 41% 40% 12% 2	1000
	11th to 20th	Night	3 5% 41% 38% 11% 2	1000
	21st to end	Night	4 8% 44% 36% 8% 1	1100

Page generated at 2025-08-31 23:51:06. Version ac07

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