SkiesAway Remote Observatories
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the SkiesAway Remote Observatories clear sky chart from 2005-11-06 to 2026-02-16.

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 3 1 3 3 3 3 3 4 6% 69%	139217
	Night	4 3 1 4 3 3 3 3 4 5% 67%	139094
Transparency	Day	18% 3 6% 18% 28% 26%	134219
	Night	21% 4 7% 19% 27% 22%	135074
Seeing	Day	6% 6% 18% 30% 27% 13%	17173
	Night	6% 2 12% 36% 37% 8%	26793

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	6% 4 2 6% 4 4 4 4 6% 7% 52%	5082
	11th to 20th	Day	4 4 2 5% 3 3 4 3 5% 5% 63%	5340
	21st to end	Day	7% 5% 2 6% 5% 5% 5% 4 6% 8% 47%	5843
February	1st to 10th	Day	10% 5% 2 5% 4 4 4 4 5% 6% 50%	1913
	11th to 20th	Day	7% 5% 2 7% 4 4 4 5% 6% 7% 50%	2001
	21st to end	Day	9% 5% 3 6% 4 4 4 5% 6% 8% 47%	1650
March	1st to 10th	Day	8% 4 2 6% 5% 6% 7% 5% 8% 8% 40%	4728
	11th to 20th	Day	5% 4 2 5% 5% 5% 5% 4 5% 6% 55%	5000
	21st to end	Day	5% 5% 2 6% 5% 6% 6% 6% 7% 9% 43%	5678
April	1st to 10th	Day	6% 5% 1 4 4 3 4 3 6% 8% 56%	2400
	11th to 20th	Day	5% 4 2 4 4 4 4 4 4 6% 59%	2369
	21st to end	Day	4 3 1 3 3 3 3 3 4 8% 65%	2400
May	1st to 10th	Day	1 2 1 2 2 2 2 2 3 4 79%	5440
	11th to 20th	Day	1 1 2 1 2 2 2 3 5% 80%	5707
	21st to end	Day	1 1 2 1 1 1 1 3 5% 83%	6902
June	1st to 10th	Day	1 1 1 2 2 2 2 2 5% 7% 75%	2800
	11th to 20th	Day	1 1 1 1 1 1 2 4 85%	2800
	21st to end	Day	1 1 1 1 1 1 1 2 3 87%	2800
July	1st to 10th	Day	1 1 1 1 1 1 2 92%	6306
	11th to 20th	Day	1 1 1 2 2 1 1 2 3 86%	5880
	21st to end	Day	1 1 2 2 2 2 2 4 5% 80%	6402
August	1st to 10th	Day	1 1 1 1 1 1 1 3 4 86%	5634
	11th to 20th	Day	1 1 1 1 1 2 92%	5364
	21st to end	Day	1 1 1 1 1 1 2 4 88%	5984
September	1st to 10th	Day	1 1 1 1 1 2 3 4 86%	2400
	11th to 20th	Day	1 1 2 1 2 2 1 3 4 80%	2400
	21st to end	Day	1 2 1 2 2 2 2 2 3 5% 77%	2175
October	1st to 10th	Day	1 1 1 2 2 2 2 3 5% 6% 77%	3280
	11th to 20th	Day	1 2 1 3 2 3 3 2 3 4 76%	3261
	21st to end	Day	2 3 1 4 4 3 3 3 5% 7% 66%	3558
November	1st to 10th	Day	3 3 1 4 4 3 4 3 5% 7% 62%	1998
	11th to 20th	Day	5% 4 2 5% 4 4 4 4 5% 6% 58%	1890
	21st to end	Day	5% 3 2 6% 4 3 4 4 6% 5% 57%	1890
December	1st to 10th	Day	4 5% 2 7% 4 3 4 3 5% 7% 55%	2742
	11th to 20th	Day	11% 6% 2 7% 5% 4 5% 5% 6% 8% 42%	3108
	21st to end	Day	10% 8% 4 9% 5% 5% 5% 4 7% 8% 34%	4092
January	1st to 10th	Night	9% 5% 2 7% 4 4 4 3 4 6% 52%	7814
	11th to 20th	Night	4 4 2 5% 3 3 3 3 4 6% 62%	7650
	21st to end	Night	8% 6% 2 8% 6% 5% 4 3 5% 7% 46%	8371
February	1st to 10th	Night	8% 5% 2 6% 4 3 4 3 5% 6% 53%	2704
	11th to 20th	Night	6% 5% 1 5% 4 3 4 3 5% 7% 56%	2398
	21st to end	Night	7% 4 2 5% 3 4 3 3 5% 6% 57%	1980
March	1st to 10th	Night	6% 7% 2 7% 5% 5% 6% 5% 6% 8% 43%	5161
	11th to 20th	Night	4 4 2 5% 4 4 4 3 5% 7% 58%	5000
	21st to end	Night	6% 4 2 6% 6% 5% 5% 4 6% 7% 50%	5284
April	1st to 10th	Night	5% 3 1 4 4 3 4 4 5% 7% 61%	2000
	11th to 20th	Night	4 3 1 3 3 2 3 3 4 6% 67%	1979
	21st to end	Night	2 2 1 3 2 3 3 3 5% 8% 68%	2000
May	1st to 10th	Night	1 1 2 1 2 2 2 3 5% 81%	4560
	11th to 20th	Night	1 1 1 2 2 2 2 2 4 6% 77%	4178
	21st to end	Night	1 1 1 1 1 1 1 2 4 88%	3972
June	1st to 10th	Night	2 1 2 2 2 2 2 4 6% 77%	1600
	11th to 20th	Night	1 1 2 1 1 1 1 2 5% 85%	1600
	21st to end	Night	1 1 1 1 1 4 90%	1600
July	1st to 10th	Night	1 1 1 2 94%	3640
	11th to 20th	Night	1 1 1 1 1 2 3 90%	4095
	21st to end	Night	1 1 2 1 1 1 2 3 5% 84%	4472
August	1st to 10th	Night	1 1 1 1 1 1 2 3 88%	4169
	11th to 20th	Night	1 1 1 1 2 2 93%	4506
	21st to end	Night	1 1 1 1 1 2 3 89%	5015
September	1st to 10th	Night	1 1 1 1 1 2 1 2 3 88%	2000
	11th to 20th	Night	1 2 1 2 2 2 2 2 2 4 82%	2000
	21st to end	Night	1 2 1 1 1 2 2 1 2 3 83%	2220
October	1st to 10th	Night	1 2 1 2 1 1 2 2 4 5% 80%	3920
	11th to 20th	Night	2 2 1 2 2 2 3 2 3 4 78%	3897
	21st to end	Night	1 2 1 4 2 2 2 2 4 5% 73%	4253
November	1st to 10th	Night	2 3 1 3 3 3 3 3 4 6% 69%	2518
	11th to 20th	Night	5% 4 1 5% 3 4 4 3 4 7% 61%	2730
	21st to end	Night	4 4 2 4 5% 4 4 4 5% 6% 59%	2730
December	1st to 10th	Night	4 4 1 4 4 4 4 4 5% 6% 61%	4656
	11th to 20th	Night	9% 6% 2 7% 5% 5% 5% 5% 8% 7% 40%	5316
	21st to end	Night	9% 9% 5% 10% 6% 6% 6% 4 6% 7% 32%	7106

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	26% 7% 12% 30% 19% 6%	5083
	11th to 20th	Day	25% 3 6% 11% 25% 30%	5340
	21st to end	Day	34% 5% 6% 16% 29% 10%	5843
February	1st to 10th	Day	34% 4 6% 19% 22% 15%	1913
	11th to 20th	Day	32% 4 9% 22% 23% 10%	2011
	21st to end	Day	33% 4 9% 21% 25% 8%	1650
March	1st to 10th	Day	35% 9% 10% 17% 25% 4	4728
	11th to 20th	Day	28% 5% 9% 33% 16% 9%	5000
	21st to end	Day	32% 7% 13% 27% 17% 3	5678
April	1st to 10th	Day	27% 4 12% 25% 24% 9%	2400
	11th to 20th	Day	25% 4 10% 25% 26% 10%	2372
	21st to end	Day	20% 3 11% 28% 30% 9%	2400
May	1st to 10th	Day	11% 2 5% 25% 42% 15%	5440
	11th to 20th	Day	10% 1 7% 31% 37% 14%	5710
	21st to end	Day	8% 1 5% 26% 47% 13%	6904
June	1st to 10th	Day	12% 2 10% 23% 34% 20%	2800
	11th to 20th	Day	7% 1 5% 14% 39% 34%	2800
	21st to end	Day	6% 1 2 10% 32% 49%	2800
July	1st to 10th	Day	3 1 4 21% 72%	6238
	11th to 20th	Day	7% 1 1 4 19% 67%	5811
	21st to end	Day	8% 1 1 13% 33% 43%	6217
August	1st to 10th	Day	7% 1 1 11% 31% 49%	4096
	11th to 20th	Day	4 1 1 5% 31% 57%	3880
	21st to end	Day	5% 1 1 10% 30% 53%	4311
September	1st to 10th	Day	6% 2 2 8% 30% 52%	2400
	11th to 20th	Day	10% 2 3 17% 40% 29%	2400
	21st to end	Day	11% 2 2 17% 38% 30%	2175
October	1st to 10th	Day	10% 3 3 13% 24% 47%	3280
	11th to 20th	Day	14% 3 5% 19% 37% 23%	3261
	21st to end	Day	19% 3 3 15% 35% 26%	3558
November	1st to 10th	Day	21% 4 6% 21% 32% 16%	1998
	11th to 20th	Day	26% 4 7% 22% 25% 15%	1890
	21st to end	Day	28% 4 6% 20% 25% 18%	1890
December	1st to 10th	Day	27% 4 4 20% 30% 14%	2742
	11th to 20th	Day	38% 5% 10% 21% 17% 9%	3108
	21st to end	Day	42% 9% 12% 20% 13% 4	4092
January	1st to 10th	Night	30% 8% 11% 26% 21% 4	7814
	11th to 20th	Night	24% 3 8% 13% 28% 23%	7650
	21st to end	Night	37% 5% 6% 17% 24% 11%	8371
February	1st to 10th	Night	32% 4 7% 20% 23% 14%	2704
	11th to 20th	Night	27% 4 8% 25% 27% 10%	2399
	21st to end	Night	28% 3 10% 25% 25% 9%	1980
March	1st to 10th	Night	37% 6% 10% 19% 24% 5%	5161
	11th to 20th	Night	26% 5% 15% 28% 17% 9%	5000
	21st to end	Night	31% 6% 14% 29% 17% 3	5284
April	1st to 10th	Night	23% 4 14% 29% 21% 10%	2000
	11th to 20th	Night	20% 2 11% 31% 26% 10%	1979
	21st to end	Night	17% 3 10% 32% 30% 8%	2000
May	1st to 10th	Night	9% 3 8% 29% 36% 15%	4557
	11th to 20th	Night	13% 1 7% 31% 33% 15%	4179
	21st to end	Night	6% 1 7% 33% 40% 13%	3972
June	1st to 10th	Night	12% 3 11% 23% 31% 20%	1600
	11th to 20th	Night	8% 2 4 16% 37% 34%	1600
	21st to end	Night	4 1 2 12% 31% 50%	1600
July	1st to 10th	Night	2 1 4 19% 74%	3600
	11th to 20th	Night	5% 1 1 4 17% 71%	4042
	21st to end	Night	7% 1 1 14% 36% 41%	4345
August	1st to 10th	Night	7% 1 1 8% 31% 51%	3027
	11th to 20th	Night	4 1 5% 24% 66%	3256
	21st to end	Night	5% 1 1 9% 32% 52%	3608
September	1st to 10th	Night	6% 1 2 8% 28% 55%	2000
	11th to 20th	Night	10% 2 3 16% 34% 36%	2000
	21st to end	Night	9% 2 3 16% 38% 32%	2220
October	1st to 10th	Night	9% 2 3 13% 30% 43%	3920
	11th to 20th	Night	13% 3 4 21% 38% 22%	3897
	21st to end	Night	15% 3 4 18% 40% 21%	4253
November	1st to 10th	Night	17% 4 7% 22% 31% 19%	2518
	11th to 20th	Night	24% 4 10% 20% 27% 16%	2730
	21st to end	Night	26% 4 9% 19% 28% 16%	2730
December	1st to 10th	Night	24% 4 5% 22% 34% 11%	4656
	11th to 20th	Night	40% 6% 10% 18% 18% 8%	5316
	21st to end	Night	47% 9% 11% 20% 10% 4	7106

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	17% 11% 26% 24% 18% 4	346
	11th to 20th	Day	10% 8% 19% 29% 28% 7%	430
	21st to end	Day	11% 8% 20% 29% 24% 8%	473
February	1st to 10th	Day	13% 11% 25% 22% 19% 10%	443
	11th to 20th	Day	12% 12% 25% 24% 21% 6%	516
	21st to end	Day	10% 11% 23% 33% 20% 3	414
March	1st to 10th	Day	14% 13% 22% 33% 17% 1	500
	11th to 20th	Day	15% 10% 25% 27% 19% 5%	500
	21st to end	Day	10% 12% 28% 32% 12% 5%	550
April	1st to 10th	Day	10% 9% 26% 28% 18% 9%	500
	11th to 20th	Day	6% 13% 26% 30% 15% 9%	492
	21st to end	Day	5% 7% 28% 31% 18% 10%	500
May	1st to 10th	Day	5% 7% 26% 33% 19% 10%	503
	11th to 20th	Day	3 8% 22% 36% 19% 13%	528
	21st to end	Day	2 9% 21% 32% 22% 14%	573
June	1st to 10th	Day	2 6% 17% 31% 26% 18%	530
	11th to 20th	Day	2 4 22% 34% 28% 12%	530
	21st to end	Day	1 2 14% 33% 29% 21%	530
July	1st to 10th	Day	8% 36% 36% 20%	526
	11th to 20th	Day	2 4 34% 32% 27%	524
	21st to end	Day	1 7% 32% 35% 24%	575
August	1st to 10th	Day	2 1 10% 32% 34% 20%	527
	11th to 20th	Day	1 1 8% 31% 34% 26%	517
	21st to end	Day	1 1 7% 30% 38% 25%	583
September	1st to 10th	Day	1 2 10% 29% 34% 24%	530
	11th to 20th	Day	3 2 15% 30% 34% 16%	530
	21st to end	Day	2 4 11% 30% 39% 14%	530
October	1st to 10th	Day	2 4 17% 30% 32% 14%	530
	11th to 20th	Day	3 5% 18% 26% 32% 14%	530
	21st to end	Day	4 3 18% 30% 32% 13%	583
November	1st to 10th	Day	4 7% 16% 26% 31% 16%	474
	11th to 20th	Day	8% 6% 18% 28% 31% 9%	330
	21st to end	Day	8% 3 18% 32% 30% 9%	330
December	1st to 10th	Day	10% 6% 18% 28% 29% 9%	234
	11th to 20th	Day	10% 5% 20% 27% 28% 10%	220
	21st to end	Day	14% 11% 28% 25% 17% 5%	242
January	1st to 10th	Night	14% 4 18% 38% 22% 5%	840
	11th to 20th	Night	9% 1 12% 45% 29% 4	840
	21st to end	Night	11% 2 12% 44% 27% 3	924
February	1st to 10th	Night	12% 4 15% 37% 27% 4	840
	11th to 20th	Night	10% 4 17% 38% 26% 4	804
	21st to end	Night	10% 3 16% 48% 20% 3	660
March	1st to 10th	Night	12% 5% 18% 40% 23% 3	800
	11th to 20th	Night	8% 3 19% 37% 28% 5%	800
	21st to end	Night	10% 3 21% 39% 26% 3	880
April	1st to 10th	Night	6% 4 20% 40% 27% 3	800
	11th to 20th	Night	7% 4 21% 35% 28% 5%	791
	21st to end	Night	3 3 24% 34% 29% 8%	800
May	1st to 10th	Night	2 3 16% 38% 33% 7%	800
	11th to 20th	Night	2 1 15% 35% 40% 6%	644
	21st to end	Night	2 1 15% 40% 35% 6%	433
June	1st to 10th	Night	3 2 9% 40% 41% 6%	400
	11th to 20th	Night	1 1 12% 40% 40% 7%	400
	21st to end	Night	7% 34% 52% 8%	400
July	1st to 10th	Night	2 26% 59% 13%	390
	11th to 20th	Night	1 1 13% 61% 25%	578
	21st to end	Night	1 1 16% 59% 23%	657
August	1st to 10th	Night	1 2 24% 58% 15%	656
	11th to 20th	Night	1 2 28% 56% 14%	792
	21st to end	Night	1 2 22% 58% 16%	880
September	1st to 10th	Night	1 2 28% 56% 13%	800
	11th to 20th	Night	2 1 6% 35% 44% 13%	800
	21st to end	Night	1 1 7% 31% 48% 11%	800
October	1st to 10th	Night	3 1 8% 39% 40% 9%	800
	11th to 20th	Night	4 2 10% 34% 42% 9%	800
	21st to end	Night	3 1 10% 35% 40% 11%	880
November	1st to 10th	Night	5% 1 11% 36% 40% 6%	820
	11th to 20th	Night	7% 2 12% 41% 34% 5%	840
	21st to end	Night	6% 2 11% 42% 35% 4	840
December	1st to 10th	Night	11% 3 11% 42% 29% 4	840
	11th to 20th	Night	12% 1 13% 43% 28% 3	840
	21st to end	Night	13% 4 19% 41% 21% 2	924

Page generated at 2026-02-12 22:42:12. Version ac07

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