SGPalisadeCO Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the SGPalisadeCO Observatory clear sky chart from 2005-11-06 to 2024-03-23.

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	4 5% 2 4 4 3 4 5% 6% 7% 54%	78884
	Night	5% 7% 3 5% 4 3 4 5% 5% 7% 53%	81068
Transparency	Day	26% 7% 11% 22% 21% 12%	78604
	Night	28% 7% 12% 23% 21% 10%	80869
Seeing	Day	7% 11% 26% 32% 20% 4	14436
	Night	7% 6% 21% 39% 23% 3	24752

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	3 6% 3 7% 7% 4 6% 7% 6% 8% 43%	2762
	11th to 20th	Day	4 11% 4 5% 6% 4 4 5% 7% 6% 43%	2860
	21st to end	Day	5% 9% 3 6% 4 2 4 3 3 6% 55%	3146
February	1st to 10th	Day	4 8% 3 6% 5% 4 4 5% 6% 9% 46%	1710
	11th to 20th	Day	5% 9% 4 6% 6% 3 5% 4 6% 8% 44%	1665
	21st to end	Day	5% 9% 4 7% 6% 3 5% 4 4 5% 46%	1579
March	1st to 10th	Day	6% 9% 3 7% 5% 3 5% 5% 5% 7% 47%	2090
	11th to 20th	Day	3 7% 3 6% 5% 3 5% 5% 5% 9% 50%	2090
	21st to end	Day	5% 8% 3 5% 6% 3 5% 5% 5% 8% 46%	2201
April	1st to 10th	Day	7% 6% 2 6% 4 3 4 5% 6% 7% 49%	2142
	11th to 20th	Day	6% 8% 3 6% 4 3 5% 5% 6% 6% 49%	2131
	21st to end	Day	4 5% 3 5% 4 3 5% 5% 6% 8% 52%	2191
May	1st to 10th	Day	5% 6% 2 5% 5% 4 6% 6% 7% 8% 45%	2340
	11th to 20th	Day	5% 5% 2 4 4 3 5% 6% 6% 10% 51%	2322
	21st to end	Day	4 4 2 4 5% 3 5% 6% 6% 8% 54%	2724
June	1st to 10th	Day	2 3 1 3 3 2 4 5% 5% 8% 64%	2520
	11th to 20th	Day	3 2 1 3 4 2 4 4 5% 6% 68%	2520
	21st to end	Day	2 2 1 3 3 1 3 4 6% 7% 68%	2520
July	1st to 10th	Day	2 2 1 3 3 3 6% 6% 7% 9% 58%	2516
	11th to 20th	Day	2 2 2 3 4 3 5% 7% 7% 11% 53%	2340
	21st to end	Day	3 3 1 4 5% 4 6% 7% 10% 11% 45%	2545
August	1st to 10th	Day	4 3 2 5% 5% 4 6% 7% 7% 8% 49%	2328
	11th to 20th	Day	3 2 1 3 4 3 5% 4 6% 8% 62%	2286
	21st to end	Day	3 2 1 3 4 3 5% 5% 7% 8% 57%	2376
September	1st to 10th	Day	5% 3 1 3 4 2 3 4 5% 6% 65%	2160
	11th to 20th	Day	3 2 1 3 5% 3 5% 4 6% 6% 63%	2104
	21st to end	Day	5% 2 2 3 3 2 2 3 4 6% 69%	1925
October	1st to 10th	Day	7% 3 2 3 3 2 4 4 4 7% 61%	1800
	11th to 20th	Day	4 2 1 2 3 2 3 4 4 7% 69%	1800
	21st to end	Day	6% 4 2 3 3 2 2 4 5% 6% 64%	1980
November	1st to 10th	Day	4 3 1 4 4 2 3 3 5% 6% 65%	1845
	11th to 20th	Day	5% 5% 2 4 4 2 3 4 3 6% 61%	1606
	21st to end	Day	4 7% 2 4 4 2 3 3 4 7% 61%	1520
December	1st to 10th	Day	5% 9% 4 7% 4 3 4 4 5% 6% 50%	1520
	11th to 20th	Day	6% 8% 4 6% 5% 3 4 5% 5% 8% 46%	1926
	21st to end	Day	5% 10% 3 5% 4 2 4 5% 6% 7% 49%	2794
January	1st to 10th	Night	3 8% 4 7% 7% 3 5% 5% 6% 7% 45%	4221
	11th to 20th	Night	4 14% 5% 7% 5% 3 3 4 7% 7% 41%	4110
	21st to end	Night	5% 12% 3 5% 4 2 4 4 5% 5% 50%	4521
February	1st to 10th	Night	4 8% 3 6% 4 3 5% 5% 6% 8% 49%	2470
	11th to 20th	Night	5% 9% 4 6% 6% 3 5% 4 6% 6% 46%	2402
	21st to end	Night	4 9% 4 6% 5% 3 4 6% 5% 7% 47%	1870
March	1st to 10th	Night	5% 7% 4 6% 4 3 5% 5% 5% 6% 50%	2090
	11th to 20th	Night	4 7% 3 4 5% 3 4 5% 6% 7% 54%	2090
	21st to end	Night	6% 7% 4 7% 6% 3 5% 6% 5% 6% 44%	2200
April	1st to 10th	Night	6% 9% 3 8% 6% 2 5% 4 5% 6% 47%	1817
	11th to 20th	Night	7% 7% 3 7% 5% 4 5% 5% 4 7% 46%	1777
	21st to end	Night	7% 6% 3 6% 4 3 4 5% 6% 7% 48%	1764
May	1st to 10th	Night	8% 5% 2 4 4 3 5% 6% 7% 8% 47%	1620
	11th to 20th	Night	6% 5% 2 4 4 2 6% 5% 6% 8% 53%	1573
	21st to end	Night	7% 5% 1 4 4 3 4 5% 6% 7% 55%	1552
June	1st to 10th	Night	2 3 1 3 3 2 3 4 5% 8% 64%	1440
	11th to 20th	Night	4 4 2 4 3 2 4 4 4 6% 64%	1440
	21st to end	Night	2 2 1 3 3 2 4 5% 4 7% 67%	1440
July	1st to 10th	Night	3 3 1 2 3 3 5% 6% 6% 10% 58%	1440
	11th to 20th	Night	2 2 1 4 4 3 5% 7% 7% 10% 56%	1620
	21st to end	Night	3 3 2 4 5% 3 7% 8% 8% 11% 47%	1773
August	1st to 10th	Night	4 3 2 4 4 2 6% 7% 8% 10% 52%	1611
	11th to 20th	Night	3 3 1 4 4 2 4 4 5% 9% 61%	1615
	21st to end	Night	3 2 1 3 4 3 5% 6% 8% 9% 57%	1980
September	1st to 10th	Night	4 3 2 3 3 2 3 4 5% 7% 64%	1800
	11th to 20th	Night	3 2 2 3 4 2 3 5% 5% 6% 65%	1853
	21st to end	Night	5% 3 1 2 3 2 3 3 4 5% 69%	2034
October	1st to 10th	Night	7% 4 2 3 3 2 3 3 4 5% 63%	2160
	11th to 20th	Night	5% 3 2 3 2 2 2 3 4 6% 68%	2160
	21st to end	Night	7% 5% 2 3 3 2 2 3 3 5% 64%	2376
November	1st to 10th	Night	4 4 2 4 3 2 3 4 4 6% 64%	2220
	11th to 20th	Night	5% 4 2 4 3 2 3 3 4 6% 63%	2565
	21st to end	Night	6% 7% 3 4 3 2 3 3 4 7% 58%	2660
December	1st to 10th	Night	6% 9% 3 5% 4 2 3 4 4 5% 54%	2660
	11th to 20th	Night	6% 8% 3 6% 5% 3 5% 5% 6% 9% 43%	3271
	21st to end	Night	5% 11% 4 7% 5% 2 4 4 4 7% 47%	4873

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% 13% 20% 27% 9% 1	2763
	11th to 20th	Day	34% 13% 22% 24% 7%	2860
	21st to end	Day	31% 8% 18% 30% 12% 2	3146
February	1st to 10th	Day	35% 8% 17% 24% 14% 2	1710
	11th to 20th	Day	36% 8% 12% 25% 16% 2	1674
	21st to end	Day	38% 7% 8% 24% 19% 4	1579
March	1st to 10th	Day	35% 6% 10% 26% 20% 2	2090
	11th to 20th	Day	30% 7% 13% 31% 15% 5%	2090
	21st to end	Day	33% 9% 10% 27% 17% 4	2201
April	1st to 10th	Day	33% 6% 10% 21% 22% 8%	2142
	11th to 20th	Day	32% 8% 9% 22% 23% 6%	2134
	21st to end	Day	28% 7% 10% 24% 25% 6%	2191
May	1st to 10th	Day	32% 8% 9% 20% 24% 7%	2340
	11th to 20th	Day	26% 8% 10% 25% 23% 9%	2325
	21st to end	Day	24% 7% 10% 19% 30% 11%	2724
June	1st to 10th	Day	18% 5% 6% 20% 30% 21%	2520
	11th to 20th	Day	17% 5% 6% 10% 24% 38%	2520
	21st to end	Day	14% 4 4 13% 26% 39%	2520
July	1st to 10th	Day	20% 6% 8% 14% 20% 32%	2447
	11th to 20th	Day	21% 7% 12% 19% 20% 21%	2271
	21st to end	Day	25% 10% 16% 21% 17% 12%	2404
August	1st to 10th	Day	30% 7% 12% 17% 15% 18%	2313
	11th to 20th	Day	20% 5% 9% 18% 25% 23%	2286
	21st to end	Day	21% 7% 9% 19% 24% 19%	2376
September	1st to 10th	Day	20% 4 7% 15% 24% 30%	2160
	11th to 20th	Day	20% 7% 9% 19% 26% 21%	2104
	21st to end	Day	18% 4 5% 17% 40% 16%	1925
October	1st to 10th	Day	24% 5% 8% 25% 27% 11%	1800
	11th to 20th	Day	16% 4 7% 25% 37% 12%	1800
	21st to end	Day	22% 5% 11% 31% 27% 6%	1980
November	1st to 10th	Day	20% 4 10% 28% 32% 6%	1845
	11th to 20th	Day	25% 5% 10% 35% 24% 3	1606
	21st to end	Day	26% 5% 12% 30% 23% 3	1520
December	1st to 10th	Day	33% 8% 20% 25% 13% 2	1520
	11th to 20th	Day	36% 6% 15% 30% 12%	1924
	21st to end	Day	32% 9% 15% 17% 23% 3	2794
January	1st to 10th	Night	33% 11% 18% 25% 12% 1	4221
	11th to 20th	Night	37% 10% 19% 25% 8% 1	4110
	21st to end	Night	34% 8% 20% 26% 10% 2	4521
February	1st to 10th	Night	32% 8% 18% 26% 14% 2	2470
	11th to 20th	Night	35% 8% 12% 25% 17% 3	2403
	21st to end	Night	34% 7% 10% 26% 19% 4	1870
March	1st to 10th	Night	33% 6% 11% 25% 23% 1	2090
	11th to 20th	Night	28% 7% 8% 29% 22% 6%	2090
	21st to end	Night	37% 8% 10% 26% 17% 3	2200
April	1st to 10th	Night	37% 5% 7% 20% 21% 10%	1817
	11th to 20th	Night	34% 7% 9% 21% 21% 9%	1777
	21st to end	Night	31% 7% 10% 21% 25% 7%	1764
May	1st to 10th	Night	32% 6% 11% 19% 24% 7%	1620
	11th to 20th	Night	26% 7% 12% 22% 26% 7%	1574
	21st to end	Night	27% 7% 8% 18% 27% 13%	1552
June	1st to 10th	Night	17% 6% 8% 17% 30% 23%	1440
	11th to 20th	Night	20% 5% 7% 12% 19% 37%	1440
	21st to end	Night	15% 4 6% 12% 24% 40%	1440
July	1st to 10th	Night	20% 7% 10% 14% 16% 34%	1400
	11th to 20th	Night	19% 6% 11% 20% 20% 23%	1566
	21st to end	Night	25% 9% 17% 19% 16% 13%	1674
August	1st to 10th	Night	24% 9% 14% 20% 18% 15%	1602
	11th to 20th	Night	19% 6% 10% 19% 20% 26%	1615
	21st to end	Night	21% 7% 9% 17% 21% 25%	1980
September	1st to 10th	Night	20% 4 8% 14% 18% 35%	1800
	11th to 20th	Night	18% 5% 11% 19% 21% 26%	1853
	21st to end	Night	18% 5% 6% 15% 35% 22%	2034
October	1st to 10th	Night	23% 4 8% 22% 26% 17%	2160
	11th to 20th	Night	17% 4 9% 21% 35% 15%	2160
	21st to end	Night	23% 4 7% 30% 28% 7%	2376
November	1st to 10th	Night	22% 5% 9% 25% 31% 8%	2220
	11th to 20th	Night	22% 6% 8% 32% 28% 4	2565
	21st to end	Night	29% 4 8% 28% 26% 4	2660
December	1st to 10th	Night	32% 6% 17% 24% 18% 2	2660
	11th to 20th	Night	36% 8% 13% 28% 15% 1	3272
	21st to end	Night	36% 8% 15% 18% 21% 2	4873

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	14% 10% 23% 32% 16% 6%	270
	11th to 20th	Day	10% 12% 29% 32% 16% 1	270
	21st to end	Day	9% 5% 25% 43% 14% 3	297
February	1st to 10th	Day	8% 12% 38% 31% 10% 1	270
	11th to 20th	Day	10% 11% 44% 26% 8% 1	270
	21st to end	Day	13% 19% 33% 27% 7% 1	249
March	1st to 10th	Day	11% 23% 29% 23% 13% 1	460
	11th to 20th	Day	8% 18% 32% 27% 13% 2	460
	21st to end	Day	12% 24% 37% 20% 6% 1	471
April	1st to 10th	Day	12% 21% 33% 21% 11% 2	420
	11th to 20th	Day	16% 24% 34% 17% 8% 1	412
	21st to end	Day	11% 18% 36% 22% 12% 1	420
May	1st to 10th	Day	9% 19% 36% 26% 10% 1	423
	11th to 20th	Day	9% 12% 28% 33% 16% 3	469
	21st to end	Day	6% 14% 28% 28% 21% 4	679
June	1st to 10th	Day	2 10% 24% 33% 27% 3	630
	11th to 20th	Day	4 12% 25% 34% 21% 4	630
	21st to end	Day	3 7% 22% 40% 24% 3	630
July	1st to 10th	Day	2 3 16% 38% 34% 7%	617
	11th to 20th	Day	2 2 18% 39% 34% 4	444
	21st to end	Day	4 2 11% 43% 34% 5%	487
August	1st to 10th	Day	5% 4 21% 39% 27% 4	447
	11th to 20th	Day	2 5% 14% 41% 30% 7%	437
	21st to end	Day	4 2 20% 38% 28% 8%	495
September	1st to 10th	Day	6% 4 22% 30% 28% 10%	450
	11th to 20th	Day	4 7% 26% 37% 19% 7%	450
	21st to end	Day	6% 10% 21% 32% 24% 7%	395
October	1st to 10th	Day	7% 13% 20% 23% 24% 12%	270
	11th to 20th	Day	4 10% 24% 32% 23% 7%	270
	21st to end	Day	7% 8% 28% 31% 23% 3	297
November	1st to 10th	Day	7% 17% 24% 31% 20% 1	270
	11th to 20th	Day	3 12% 33% 34% 14% 4	270
	21st to end	Day	11% 10% 23% 36% 19% 1	270
December	1st to 10th	Day	9% 10% 30% 33% 16% 3	270
	11th to 20th	Day	10% 9% 27% 36% 14% 4	270
	21st to end	Day	12% 10% 31% 33% 12% 2	297
January	1st to 10th	Night	8% 5% 20% 42% 22% 3	832
	11th to 20th	Night	9% 7% 20% 41% 20% 3	760
	21st to end	Night	11% 5% 19% 45% 17% 3	836
February	1st to 10th	Night	8% 5% 27% 44% 14% 2	760
	11th to 20th	Night	10% 6% 31% 38% 13% 2	744
	21st to end	Night	8% 10% 29% 43% 9% 1	628
March	1st to 10th	Night	8% 11% 26% 38% 15% 1	760
	11th to 20th	Night	7% 6% 25% 42% 19% 1	760
	21st to end	Night	9% 9% 28% 37% 16% 2	800
April	1st to 10th	Night	9% 11% 30% 38% 11% 1	557
	11th to 20th	Night	11% 9% 26% 39% 13% 2	533
	21st to end	Night	9% 10% 27% 34% 15% 5%	540
May	1st to 10th	Night	10% 6% 26% 40% 15% 2	540
	11th to 20th	Night	8% 5% 19% 38% 25% 5%	531
	21st to end	Night	8% 10% 20% 33% 25% 4	584
June	1st to 10th	Night	2 6% 20% 41% 28% 4	540
	11th to 20th	Night	5% 6% 21% 43% 22% 3	540
	21st to end	Night	3 3 17% 41% 33% 3	540
July	1st to 10th	Night	3 1 12% 33% 45% 6%	525
	11th to 20th	Night	2 1 7% 36% 47% 6%	522
	21st to end	Night	3 1 6% 35% 50% 6%	591
August	1st to 10th	Night	5% 2 9% 34% 45% 4	537
	11th to 20th	Night	4 1 9% 41% 39% 5%	534
	21st to end	Night	4 1 10% 39% 39% 8%	594
September	1st to 10th	Night	4 1 15% 40% 34% 5%	540
	11th to 20th	Night	3 3 17% 39% 34% 5%	593
	21st to end	Night	6% 5% 17% 32% 33% 8%	720
October	1st to 10th	Night	8% 5% 20% 39% 24% 4	720
	11th to 20th	Night	6% 4 22% 39% 25% 4	720
	21st to end	Night	8% 6% 23% 35% 24% 4	792
November	1st to 10th	Night	6% 7% 21% 39% 25% 2	740
	11th to 20th	Night	6% 7% 22% 43% 19% 3	944
	21st to end	Night	9% 8% 20% 39% 20% 4	950
December	1st to 10th	Night	9% 6% 22% 46% 17% 1	950
	11th to 20th	Night	11% 6% 23% 40% 18% 2	950
	21st to end	Night	12% 8% 23% 44% 12% 1	1045

Page generated at 2024-03-19 21:31:03. Version ac07

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