Wolf Creek Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Wolf Creek Observatory clear sky chart from 2005-11-06 to 2024-01-15.

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	11% 6% 3 5% 6% 4 5% 5% 6% 8% 42%	74818
	Night	11% 6% 3 5% 5% 3 5% 5% 6% 8% 45%	74974
Transparency	Day	39% 7% 11% 18% 18% 6%	74550
	Night	36% 7% 11% 17% 20% 8%	74761
Seeing	Day	14% 9% 22% 24% 21% 10%	13465
	Night	13% 8% 22% 30% 22% 5%	23499

By Month

Percentage Cloud Cover SE (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	15% 7% 4 6% 3 3 3 3 5% 7% 44%	1706
	11th to 20th	Day	13% 8% 3 5% 4 2 4 5% 4 8% 44%	1817
	21st to end	Day	17% 5% 3 5% 4 2 4 4 4 5% 45%	1980
February	1st to 10th	Day	16% 8% 3 6% 6% 3 4 4 5% 6% 39%	1800
	11th to 20th	Day	16% 7% 2 5% 5% 3 4 4 4 6% 43%	1748
	21st to end	Day	17% 7% 3 6% 6% 3 4 5% 4 6% 38%	1480
March	1st to 10th	Day	10% 7% 3 5% 5% 3 4 4 5% 7% 46%	1800
	11th to 20th	Day	13% 7% 3 5% 6% 4 4 4 6% 7% 40%	1895
	21st to end	Day	12% 6% 2 6% 5% 3 4 4 5% 8% 45%	2282
April	1st to 10th	Day	12% 5% 3 5% 5% 3 5% 5% 5% 7% 46%	2160
	11th to 20th	Day	12% 6% 2 5% 6% 3 4 5% 6% 7% 45%	2134
	21st to end	Day	7% 4 2 4 5% 3 4 5% 5% 6% 54%	2160
May	1st to 10th	Day	9% 4 2 4 5% 3 5% 4 5% 9% 50%	2240
	11th to 20th	Day	7% 4 2 6% 5% 4 6% 7% 6% 9% 43%	2301
	21st to end	Day	7% 6% 3 6% 6% 4 6% 6% 7% 8% 42%	2531
June	1st to 10th	Day	8% 6% 3 8% 9% 5% 6% 7% 6% 10% 33%	2340
	11th to 20th	Day	6% 4 2 5% 6% 5% 7% 8% 7% 11% 39%	2340
	21st to end	Day	6% 4 3 8% 7% 5% 8% 8% 8% 10% 33%	2340
July	1st to 10th	Day	9% 6% 3 6% 7% 5% 8% 9% 9% 11% 28%	2340
	11th to 20th	Day	8% 5% 2 7% 9% 6% 8% 8% 9% 10% 28%	2340
	21st to end	Day	6% 5% 3 6% 9% 5% 7% 8% 9% 10% 31%	2388
August	1st to 10th	Day	6% 4 2 5% 8% 6% 8% 7% 8% 13% 34%	2148
	11th to 20th	Day	11% 6% 2 7% 6% 4 7% 7% 9% 11% 30%	2125
	21st to end	Day	11% 7% 3 6% 7% 5% 6% 6% 7% 10% 32%	2376
September	1st to 10th	Day	8% 6% 4 6% 7% 4 7% 6% 5% 8% 38%	2108
	11th to 20th	Day	12% 6% 2 6% 6% 4 5% 4 6% 7% 40%	1980
	21st to end	Day	8% 5% 2 4 5% 3 5% 5% 5% 7% 49%	1980
October	1st to 10th	Day	9% 5% 2 5% 5% 3 4 4 4 7% 53%	1980
	11th to 20th	Day	11% 4 2 3 4 2 3 4 6% 7% 54%	1980
	21st to end	Day	12% 5% 2 4 4 2 3 4 4 6% 54%	1940
November	1st to 10th	Day	10% 5% 2 4 4 3 4 3 4 5% 57%	1672
	11th to 20th	Day	12% 6% 3 4 3 2 4 3 4 7% 53%	1710
	21st to end	Day	13% 5% 3 4 5% 3 4 4 5% 8% 46%	1710
December	1st to 10th	Day	13% 7% 3 5% 6% 3 4 4 4 6% 45%	1710
	11th to 20th	Day	16% 10% 3 6% 4 3 4 3 4 5% 43%	2153
	21st to end	Day	17% 10% 3 5% 5% 3 4 3 5% 5% 40%	3124
January	1st to 10th	Night	14% 8% 3 5% 4 3 3 4 3 5% 48%	2459
	11th to 20th	Night	15% 9% 3 5% 4 2 3 3 5% 6% 44%	2244
	21st to end	Night	18% 7% 3 5% 4 2 4 3 3 5% 44%	2376
February	1st to 10th	Night	14% 9% 3 6% 4 3 3 4 6% 6% 41%	2160
	11th to 20th	Night	17% 7% 3 4 4 2 3 3 4 5% 47%	2098
	21st to end	Night	15% 7% 3 5% 5% 3 4 5% 6% 7% 40%	1776
March	1st to 10th	Night	12% 7% 3 5% 4 2 3 3 5% 7% 49%	2160
	11th to 20th	Night	11% 7% 4 7% 6% 3 4 4 5% 7% 42%	2063
	21st to end	Night	11% 4 2 5% 5% 3 4 4 5% 7% 50%	2087
April	1st to 10th	Night	9% 6% 3 5% 4 3 4 5% 6% 7% 48%	1800
	11th to 20th	Night	13% 5% 2 4 4 3 4 5% 6% 8% 46%	1775
	21st to end	Night	6% 4 1 4 4 2 5% 5% 5% 7% 57%	1800
May	1st to 10th	Night	8% 4 2 4 3 3 4 4 4 8% 54%	1717
	11th to 20th	Night	7% 4 2 6% 7% 3 6% 6% 7% 11% 42%	1592
	21st to end	Night	7% 4 2 6% 6% 3 6% 5% 7% 11% 44%	1744
June	1st to 10th	Night	6% 6% 2 6% 7% 5% 6% 6% 9% 13% 33%	1620
	11th to 20th	Night	4 3 2 4 4 4 5% 7% 8% 13% 44%	1620
	21st to end	Night	4 5% 3 6% 7% 4 6% 7% 9% 12% 38%	1620
July	1st to 10th	Night	6% 5% 3 5% 8% 5% 7% 9% 10% 11% 31%	1620
	11th to 20th	Night	5% 3 3 6% 7% 4 7% 8% 9% 13% 35%	1620
	21st to end	Night	4 4 2 6% 6% 4 7% 7% 9% 12% 40%	1924
August	1st to 10th	Night	5% 4 2 5% 5% 5% 7% 9% 9% 14% 36%	1790
	11th to 20th	Night	6% 5% 2 6% 8% 5% 6% 8% 8% 12% 34%	1776
	21st to end	Night	9% 6% 4 6% 6% 4 6% 6% 7% 9% 37%	1980
September	1st to 10th	Night	9% 5% 3 5% 6% 4 6% 7% 8% 9% 38%	1832
	11th to 20th	Night	11% 6% 2 5% 6% 3 6% 6% 6% 8% 41%	1980
	21st to end	Night	8% 5% 2 5% 4 4 5% 6% 6% 8% 47%	1980
October	1st to 10th	Night	7% 5% 2 4 4 3 4 4 4 7% 56%	1980
	11th to 20th	Night	10% 5% 1 3 4 2 4 3 4 5% 58%	1980
	21st to end	Night	11% 6% 2 5% 4 3 3 2 4 5% 55%	2411
November	1st to 10th	Night	9% 4 2 4 4 2 3 4 5% 6% 57%	2406
	11th to 20th	Night	12% 5% 2 3 3 2 3 4 4 5% 56%	2470
	21st to end	Night	13% 6% 2 4 5% 2 4 4 5% 6% 48%	2470
December	1st to 10th	Night	14% 6% 2 5% 4 2 3 4 5% 7% 47%	2470
	11th to 20th	Night	15% 7% 3 5% 5% 3 4 4 4 5% 46%	3042
	21st to end	Night	16% 8% 3 5% 5% 3 4 4 5% 7% 39%	4532

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	41% 4 6% 16% 27% 6%	1707
	11th to 20th	Day	40% 4 8% 16% 24% 9%	1817
	21st to end	Day	41% 4 5% 16% 25% 9%	1980
February	1st to 10th	Day	46% 4 8% 15% 20% 8%	1800
	11th to 20th	Day	43% 4 5% 15% 24% 9%	1758
	21st to end	Day	46% 5% 7% 14% 17% 10%	1480
March	1st to 10th	Day	37% 5% 7% 19% 22% 11%	1800
	11th to 20th	Day	43% 5% 11% 15% 18% 9%	1895
	21st to end	Day	39% 5% 9% 18% 22% 6%	2282
April	1st to 10th	Day	37% 6% 9% 20% 19% 9%	2160
	11th to 20th	Day	37% 6% 8% 19% 20% 10%	2134
	21st to end	Day	29% 6% 8% 22% 29% 5%	2160
May	1st to 10th	Day	32% 6% 8% 22% 26% 6%	2240
	11th to 20th	Day	36% 10% 14% 21% 17% 2	2305
	21st to end	Day	36% 9% 11% 21% 20% 3	2531
June	1st to 10th	Day	44% 9% 13% 21% 11% 2	2340
	11th to 20th	Day	35% 11% 16% 23% 13% 3	2340
	21st to end	Day	41% 12% 18% 17% 10% 2	2340
July	1st to 10th	Day	44% 15% 20% 13% 7% 1	2275
	11th to 20th	Day	45% 15% 19% 15% 5% 1	2271
	21st to end	Day	41% 13% 21% 20% 5%	2254
August	1st to 10th	Day	37% 13% 21% 22% 6%	2136
	11th to 20th	Day	43% 15% 17% 14% 9% 2	2125
	21st to end	Day	46% 9% 16% 16% 9% 3	2376
September	1st to 10th	Day	41% 10% 15% 14% 15% 6%	2108
	11th to 20th	Day	41% 8% 13% 15% 18% 5%	1980
	21st to end	Day	34% 7% 10% 18% 23% 7%	1980
October	1st to 10th	Day	31% 5% 11% 18% 24% 12%	1980
	11th to 20th	Day	30% 4 8% 20% 27% 11%	1980
	21st to end	Day	33% 3 6% 14% 29% 16%	1940
November	1st to 10th	Day	31% 4 7% 18% 27% 13%	1672
	11th to 20th	Day	33% 4 6% 16% 27% 13%	1710
	21st to end	Day	37% 5% 8% 17% 22% 11%	1710
December	1st to 10th	Day	39% 6% 9% 18% 21% 7%	1710
	11th to 20th	Day	46% 3 6% 14% 26% 6%	2150
	21st to end	Day	46% 3 6% 21% 19% 5%	3124
January	1st to 10th	Night	40% 4 6% 17% 25% 8%	2459
	11th to 20th	Night	42% 4 7% 18% 23% 7%	2244
	21st to end	Night	44% 4 5% 12% 26% 10%	2376
February	1st to 10th	Night	42% 5% 7% 16% 19% 10%	2160
	11th to 20th	Night	41% 4 6% 14% 23% 11%	2099
	21st to end	Night	42% 6% 8% 16% 15% 13%	1776
March	1st to 10th	Night	36% 4 8% 16% 23% 13%	2160
	11th to 20th	Night	41% 6% 10% 16% 18% 9%	2063
	21st to end	Night	34% 5% 10% 19% 23% 9%	2087
April	1st to 10th	Night	35% 6% 12% 16% 21% 12%	1800
	11th to 20th	Night	35% 5% 9% 18% 23% 10%	1775
	21st to end	Night	24% 7% 9% 26% 25% 8%	1800
May	1st to 10th	Night	29% 6% 9% 21% 25% 8%	1717
	11th to 20th	Night	34% 10% 17% 18% 16% 5%	1593
	21st to end	Night	34% 9% 13% 20% 19% 5%	1745
June	1st to 10th	Night	40% 11% 17% 17% 15%	1620
	11th to 20th	Night	27% 11% 21% 25% 13% 3	1620
	21st to end	Night	34% 12% 21% 18% 10% 4	1620
July	1st to 10th	Night	39% 17% 23% 14% 7% 1	1575
	11th to 20th	Night	35% 16% 27% 16% 5% 1	1566
	21st to end	Night	30% 15% 24% 23% 7% 1	1817
August	1st to 10th	Night	33% 17% 24% 22% 4 1	1778
	11th to 20th	Night	39% 15% 20% 14% 10% 3	1776
	21st to end	Night	41% 12% 16% 14% 13% 3	1980
September	1st to 10th	Night	39% 11% 15% 14% 13% 7%	1832
	11th to 20th	Night	38% 9% 11% 19% 16% 7%	1980
	21st to end	Night	33% 9% 10% 19% 20% 9%	1980
October	1st to 10th	Night	28% 5% 11% 17% 24% 15%	1980
	11th to 20th	Night	28% 4 8% 18% 29% 13%	1980
	21st to end	Night	33% 3 5% 14% 27% 18%	2411
November	1st to 10th	Night	28% 5% 8% 17% 26% 17%	2406
	11th to 20th	Night	31% 3 5% 17% 30% 14%	2470
	21st to end	Night	36% 4 7% 19% 21% 13%	2470
December	1st to 10th	Night	37% 5% 10% 19% 23% 6%	2470
	11th to 20th	Night	41% 4 6% 13% 29% 7%	3044
	21st to end	Night	43% 5% 8% 18% 22% 4	4532

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	21% 24% 34% 18% 2 1	270
	11th to 20th	Day	20% 20% 33% 17% 9% 2	254
	21st to end	Day	22% 22% 38% 15% 2 1	264
February	1st to 10th	Day	28% 22% 31% 16% 3	240
	11th to 20th	Day	29% 20% 33% 16% 2	240
	21st to end	Day	19% 24% 39% 17%	198
March	1st to 10th	Day	20% 19% 43% 12% 5% 1	240
	11th to 20th	Day	20% 19% 34% 19% 7% 1	335
	21st to end	Day	19% 16% 33% 25% 6%	462
April	1st to 10th	Day	19% 15% 32% 20% 12% 2	420
	11th to 20th	Day	18% 12% 33% 23% 13% 1	412
	21st to end	Day	11% 12% 29% 29% 16% 5%	420
May	1st to 10th	Day	9% 11% 27% 28% 20% 5%	423
	11th to 20th	Day	8% 3 23% 31% 25% 11%	447
	21st to end	Day	12% 2 18% 31% 21% 15%	485
June	1st to 10th	Day	8% 4 13% 34% 27% 14%	450
	11th to 20th	Day	8% 2 13% 27% 30% 19%	450
	21st to end	Day	8% 3 13% 27% 30% 20%	450
July	1st to 10th	Day	9% 2 5% 24% 38% 22%	445
	11th to 20th	Day	6% 1 7% 22% 35% 30%	444
	21st to end	Day	4 1 6% 23% 44% 22%	488
August	1st to 10th	Day	7% 2 7% 19% 38% 29%	446
	11th to 20th	Day	10% 1 6% 20% 37% 26%	439
	21st to end	Day	13% 1 8% 26% 30% 22%	495
September	1st to 10th	Day	8% 2 11% 27% 34% 19%	450
	11th to 20th	Day	14% 3 11% 28% 32% 12%	450
	21st to end	Day	9% 3 15% 30% 32% 12%	450
October	1st to 10th	Day	12% 3 24% 31% 24% 6%	450
	11th to 20th	Day	13% 6% 20% 29% 26% 5%	450
	21st to end	Day	19% 13% 23% 25% 16% 3	351
November	1st to 10th	Day	17% 10% 25% 32% 14% 3	270
	11th to 20th	Day	16% 14% 38% 22% 8% 1	270
	21st to end	Day	14% 16% 34% 25% 9% 1	270
December	1st to 10th	Day	20% 18% 34% 19% 8% 1	270
	11th to 20th	Day	25% 19% 34% 16% 5%	270
	21st to end	Day	22% 19% 33% 21% 5% 1	297
January	1st to 10th	Night	20% 16% 34% 26% 4	760
	11th to 20th	Night	19% 16% 27% 29% 8%	740
	21st to end	Night	23% 14% 35% 24% 4	792
February	1st to 10th	Night	19% 13% 33% 31% 5%	720
	11th to 20th	Night	22% 15% 32% 26% 6%	703
	21st to end	Night	18% 17% 36% 27% 3	592
March	1st to 10th	Night	14% 15% 35% 28% 7%	720
	11th to 20th	Night	13% 15% 36% 24% 11%	720
	21st to end	Night	14% 15% 34% 28% 9%	701
April	1st to 10th	Night	12% 12% 32% 31% 12% 1	540
	11th to 20th	Night	17% 8% 32% 26% 15% 2	533
	21st to end	Night	7% 9% 25% 39% 20%	540
May	1st to 10th	Night	9% 6% 26% 35% 21% 4	540
	11th to 20th	Night	8% 3 22% 34% 28% 5%	531
	21st to end	Night	8% 1 14% 35% 37% 5%	584
June	1st to 10th	Night	9% 1 11% 36% 36% 6%	540
	11th to 20th	Night	5% 2 9% 27% 43% 14%	540
	21st to end	Night	4 1 10% 30% 44% 11%	540
July	1st to 10th	Night	8% 1 6% 24% 45% 17%	525
	11th to 20th	Night	6% 1 5% 20% 47% 21%	522
	21st to end	Night	5% 1 5% 29% 46% 15%	591
August	1st to 10th	Night	7% 4 22% 47% 20%	537
	11th to 20th	Night	8% 2 5% 27% 45% 13%	534
	21st to end	Night	9% 2 8% 26% 39% 16%	594
September	1st to 10th	Night	10% 1 8% 27% 40% 14%	572
	11th to 20th	Night	13% 2 13% 31% 34% 7%	720
	21st to end	Night	9% 1 14% 31% 39% 5%	720
October	1st to 10th	Night	10% 2 20% 38% 26% 3	720
	11th to 20th	Night	12% 5% 20% 32% 27% 3	720
	21st to end	Night	15% 7% 21% 35% 20% 2	792
November	1st to 10th	Night	10% 6% 22% 37% 21% 3	740
	11th to 20th	Night	15% 8% 28% 34% 14% 2	760
	21st to end	Night	16% 13% 24% 34% 12% 1	760
December	1st to 10th	Night	17% 12% 26% 32% 12% 1	760
	11th to 20th	Night	19% 11% 31% 29% 9%	760
	21st to end	Night	24% 14% 28% 26% 8%	836

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