Wolf Creek Estates Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Wolf Creek Estates Observatory clear sky chart from 2005-11-06 to 2025-06-10.

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 4 3 3 4 4 5% 7% 62%	122853
	Night	2 3 1 3 2 3 3 3 5% 7% 67%	124320
Transparency	Day	19% 7% 8% 16% 28% 22%	122618
	Night	16% 7% 7% 18% 30% 23%	124143
Seeing	Day	11% 18% 27% 25% 15% 3	15609
	Night	8% 15% 25% 31% 18% 3	25839

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 5% 1 3 2 3 4 5% 6% 7% 63%	4098
	11th to 20th	Day	1 2 3 3 2 2 2 2 4 6% 74%	4100
	21st to end	Day	2 4 2 4 3 3 4 4 5% 8% 61%	4510
February	1st to 10th	Day	1 4 1 3 3 2 3 4 5% 6% 67%	1942
	11th to 20th	Day	1 4 1 3 3 3 3 3 5% 6% 68%	1949
	21st to end	Day	3 1 2 2 3 3 4 5% 5% 73%	1650
March	1st to 10th	Day	1 5% 2 3 3 2 3 3 5% 6% 68%	4718
	11th to 20th	Day	2 8% 1 3 3 3 3 2 5% 6% 65%	5000
	21st to end	Day	1 3 2 3 2 3 3 3 5% 9% 65%	5700
April	1st to 10th	Day	2 3 1 2 2 2 3 3 5% 7% 70%	2400
	11th to 20th	Day	3 3 1 3 2 3 4 4 4 5% 70%	2371
	21st to end	Day	2 2 1 2 2 2 3 2 4 6% 74%	2400
May	1st to 10th	Day	1 3 1 3 2 2 3 2 5% 6% 71%	5440
	11th to 20th	Day	2 2 1 3 2 3 3 2 4 6% 72%	5405
	21st to end	Day	1 1 2 1 2 2 3 5% 9% 74%	6554
June	1st to 10th	Day	2 2 1 3 3 4 4 4 7% 9% 61%	2788
	11th to 20th	Day	2 2 1 3 2 3 3 3 5% 7% 70%	2660
	21st to end	Day	7% 4 1 5% 5% 4 5% 5% 7% 8% 47%	2660
July	1st to 10th	Day	6% 4 2 5% 4 5% 7% 6% 9% 12% 42%	4145
	11th to 20th	Day	4 3 1 5% 4 6% 7% 7% 9% 11% 43%	4110
	21st to end	Day	8% 5% 2 6% 6% 7% 8% 7% 9% 11% 32%	4454
August	1st to 10th	Day	4 3 1 6% 4 7% 7% 7% 9% 11% 41%	3794
	11th to 20th	Day	5% 3 1 5% 4 6% 6% 6% 8% 8% 47%	3726
	21st to end	Day	7% 4 1 6% 6% 7% 7% 6% 9% 11% 36%	4180
September	1st to 10th	Day	8% 6% 3 7% 4 5% 6% 4 5% 8% 44%	2280
	11th to 20th	Day	8% 5% 2 5% 4 4 4 4 5% 7% 53%	2275
	21st to end	Day	4 3 1 4 3 3 4 3 4 6% 66%	2090
October	1st to 10th	Day	4 3 1 3 2 2 2 2 4 5% 71%	3182
	11th to 20th	Day	5% 3 1 3 2 3 3 2 4 6% 68%	3150
	21st to end	Day	2 2 1 1 1 1 1 2 3 85%	3438
November	1st to 10th	Day	3 2 2 2 2 2 3 3 6% 74%	1952
	11th to 20th	Day	1 2 1 3 2 2 2 2 5% 7% 73%	1800
	21st to end	Day	2 4 1 3 2 3 4 4 5% 6% 66%	1800
December	1st to 10th	Day	2 3 2 3 2 2 3 2 5% 7% 69%	2940
	11th to 20th	Day	1 2 2 4 3 3 3 3 5% 6% 68%	3036
	21st to end	Day	2 1 3 1 2 3 2 3 7% 76%	4156
January	1st to 10th	Night	1 5% 2 4 2 3 4 4 4 6% 65%	5867
	11th to 20th	Night	1 1 1 3 2 2 2 2 4 5% 77%	5880
	21st to end	Night	2 4 1 3 3 3 3 3 6% 9% 63%	6468
February	1st to 10th	Night	1 2 1 3 3 3 2 3 5% 8% 69%	2455
	11th to 20th	Night	1 3 1 3 2 2 3 3 4 7% 70%	2338
	21st to end	Night	1 2 1 2 2 2 3 3 5% 7% 71%	1980
March	1st to 10th	Night	3 1 2 1 2 2 3 4 7% 74%	5163
	11th to 20th	Night	3 10% 2 3 2 2 2 2 3 5% 67%	5000
	21st to end	Night	1 1 2 2 2 3 2 4 8% 76%	5263
April	1st to 10th	Night	1 3 1 3 2 3 3 3 5% 6% 71%	2000
	11th to 20th	Night	2 3 1 1 2 2 3 3 4 7% 72%	1977
	21st to end	Night	2 3 1 2 2 2 3 3 5% 6% 73%	2000
May	1st to 10th	Night	3 3 1 2 2 2 3 2 4 6% 71%	4540
	11th to 20th	Night	2 2 1 2 2 2 3 3 4 7% 74%	4510
	21st to end	Night	1 1 1 1 2 2 3 4 5% 80%	4333
June	1st to 10th	Night	3 3 2 4 3 3 4 4 8% 9% 57%	1596
	11th to 20th	Night	2 2 1 2 2 2 3 3 6% 7% 70%	1520
	21st to end	Night	6% 4 2 5% 5% 5% 5% 5% 6% 8% 50%	1520
July	1st to 10th	Night	6% 4 1 4 4 4 4 5% 9% 12% 48%	2818
	11th to 20th	Night	3 2 1 5% 5% 5% 5% 5% 7% 10% 51%	2860
	21st to end	Night	8% 6% 2 5% 4 5% 6% 4 9% 14% 38%	3109
August	1st to 10th	Night	3 3 1 4 3 4 5% 5% 9% 15% 49%	3143
	11th to 20th	Night	3 2 1 3 3 4 4 4 7% 12% 57%	3113
	21st to end	Night	4 3 2 5% 4 5% 6% 5% 9% 14% 43%	3487
September	1st to 10th	Night	7% 3 1 4 4 4 5% 4 7% 8% 51%	1900
	11th to 20th	Night	6% 3 2 4 2 3 3 3 5% 8% 61%	1903
	21st to end	Night	3 3 1 3 3 3 3 3 4 7% 68%	2090
October	1st to 10th	Night	2 2 1 2 2 2 2 2 3 4 77%	3784
	11th to 20th	Night	2 2 1 3 2 2 3 2 4 5% 75%	3778
	21st to end	Night	2 1 1 2 1 1 1 2 3 5% 81%	4120
November	1st to 10th	Night	3 2 1 2 2 2 2 3 4 7% 72%	2340
	11th to 20th	Night	1 2 3 2 2 3 2 5% 6% 73%	2585
	21st to end	Night	2 5% 1 3 3 2 2 2 6% 7% 66%	2600
December	1st to 10th	Night	1 3 2 4 2 2 3 3 4 8% 70%	4250
	11th to 20th	Night	1 2 1 2 2 3 3 3 5% 7% 70%	5166
	21st to end	Night	1 2 1 3 2 3 3 2 4 7% 72%	6864

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% 11% 4 14% 37% 17%	4099
	11th to 20th	Day	11% 7% 5% 17% 38% 21%	4100
	21st to end	Day	20% 10% 3 11% 29% 27%	4510
February	1st to 10th	Day	18% 6% 6% 18% 27% 26%	1942
	11th to 20th	Day	18% 7% 5% 20% 29% 22%	1959
	21st to end	Day	14% 8% 3 11% 31% 33%	1650
March	1st to 10th	Day	17% 5% 3 9% 27% 38%	4718
	11th to 20th	Day	21% 5% 4 11% 28% 31%	5000
	21st to end	Day	15% 8% 5% 17% 35% 20%	5700
April	1st to 10th	Day	15% 6% 4 15% 36% 24%	2400
	11th to 20th	Day	17% 5% 4 13% 31% 31%	2374
	21st to end	Day	13% 5% 4 17% 35% 25%	2400
May	1st to 10th	Day	13% 6% 6% 14% 34% 26%	5440
	11th to 20th	Day	15% 4 5% 13% 32% 31%	5408
	21st to end	Day	8% 5% 9% 11% 19% 47%	6555
June	1st to 10th	Day	17% 7% 13% 19% 23% 20%	2788
	11th to 20th	Day	14% 5% 5% 15% 25% 36%	2660
	21st to end	Day	31% 8% 12% 17% 19% 13%	2660
July	1st to 10th	Day	29% 13% 19% 15% 14% 10%	4081
	11th to 20th	Day	29% 11% 15% 21% 21% 3	4041
	21st to end	Day	36% 14% 19% 22% 9% 1	4314
August	1st to 10th	Day	29% 12% 15% 26% 16% 2	3781
	11th to 20th	Day	29% 10% 13% 21% 24% 2	3762
	21st to end	Day	36% 12% 17% 24% 9% 2	4179
September	1st to 10th	Day	37% 9% 9% 16% 20% 8%	2280
	11th to 20th	Day	31% 7% 8% 19% 25% 11%	2275
	21st to end	Day	20% 6% 6% 21% 32% 15%	2090
October	1st to 10th	Day	17% 5% 5% 11% 31% 31%	3182
	11th to 20th	Day	17% 6% 5% 17% 33% 21%	3150
	21st to end	Day	8% 3 2 14% 39% 34%	3438
November	1st to 10th	Day	13% 5% 3 21% 36% 22%	1952
	11th to 20th	Day	14% 5% 6% 20% 31% 24%	1800
	21st to end	Day	20% 7% 5% 18% 28% 22%	1800
December	1st to 10th	Day	16% 6% 4 20% 32% 21%	2940
	11th to 20th	Day	17% 7% 5% 14% 37% 21%	3034
	21st to end	Day	12% 5% 5% 17% 34% 27%	4156
January	1st to 10th	Night	19% 9% 4 14% 39% 15%	5867
	11th to 20th	Night	10% 7% 4 15% 40% 24%	5880
	21st to end	Night	18% 10% 4 13% 25% 29%	6468
February	1st to 10th	Night	13% 6% 7% 20% 26% 28%	2455
	11th to 20th	Night	16% 7% 4 19% 30% 23%	2338
	21st to end	Night	13% 8% 4 15% 29% 31%	1980
March	1st to 10th	Night	12% 6% 3 10% 36% 33%	5163
	11th to 20th	Night	22% 5% 4 12% 32% 26%	5000
	21st to end	Night	9% 7% 5% 22% 37% 20%	5263
April	1st to 10th	Night	14% 6% 4 16% 37% 23%	2000
	11th to 20th	Night	13% 6% 6% 14% 32% 30%	1977
	21st to end	Night	12% 6% 5% 18% 36% 24%	2000
May	1st to 10th	Night	14% 4 6% 17% 33% 26%	4537
	11th to 20th	Night	12% 4 5% 14% 35% 30%	4511
	21st to end	Night	8% 4 6% 10% 15% 57%	4334
June	1st to 10th	Night	21% 7% 9% 18% 22% 22%	1596
	11th to 20th	Night	12% 4 5% 20% 19% 39%	1520
	21st to end	Night	30% 9% 12% 17% 15% 17%	1520
July	1st to 10th	Night	24% 10% 19% 19% 17% 9%	2773
	11th to 20th	Night	25% 9% 14% 28% 21% 3	2806
	21st to end	Night	32% 10% 21% 26% 10% 1	3011
August	1st to 10th	Night	21% 9% 19% 31% 18% 3	3133
	11th to 20th	Night	18% 8% 14% 30% 29% 2	3143
	21st to end	Night	27% 11% 21% 25% 15% 1	3487
September	1st to 10th	Night	28% 8% 13% 20% 22% 10%	1900
	11th to 20th	Night	23% 6% 11% 19% 27% 13%	1903
	21st to end	Night	17% 5% 9% 22% 33% 13%	2090
October	1st to 10th	Night	13% 4 6% 13% 34% 31%	3784
	11th to 20th	Night	13% 5% 7% 17% 30% 27%	3778
	21st to end	Night	9% 3 3 15% 36% 34%	4120
November	1st to 10th	Night	13% 5% 5% 19% 35% 23%	2340
	11th to 20th	Night	12% 5% 5% 20% 33% 25%	2585
	21st to end	Night	19% 6% 6% 16% 32% 21%	2600
December	1st to 10th	Night	16% 6% 6% 22% 30% 20%	4250
	11th to 20th	Night	14% 6% 6% 16% 31% 27%	5167
	21st to end	Night	14% 7% 4 17% 35% 23%	6864

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	15% 29% 31% 21% 4	300
	11th to 20th	Day	20% 22% 30% 22% 5% 1	300
	21st to end	Day	14% 27% 32% 18% 8% 1	330
February	1st to 10th	Day	15% 34% 25% 20% 6%	300
	11th to 20th	Day	21% 31% 31% 13% 4	300
	21st to end	Day	29% 34% 19% 12% 6%	249
March	1st to 10th	Day	18% 32% 32% 13% 5%	388
	11th to 20th	Day	21% 31% 30% 12% 5% 1	500
	21st to end	Day	23% 32% 32% 9% 4 1	550
April	1st to 10th	Day	16% 33% 35% 12% 3 1	500
	11th to 20th	Day	19% 37% 31% 11% 2	492
	21st to end	Day	15% 34% 34% 13% 3	500
May	1st to 10th	Day	7% 29% 46% 14% 3 1	503
	11th to 20th	Day	11% 23% 38% 20% 7%	528
	21st to end	Day	5% 21% 39% 25% 8% 1	722
June	1st to 10th	Day	3 9% 30% 37% 18% 2	726
	11th to 20th	Day	4 10% 29% 35% 20% 2	680
	21st to end	Day	8% 7% 20% 35% 26% 5%	680
July	1st to 10th	Day	5% 1 19% 43% 27% 6%	508
	11th to 20th	Day	5% 11% 37% 36% 11%	484
	21st to end	Day	5% 1 9% 34% 36% 14%	531
August	1st to 10th	Day	7% 2 10% 34% 37% 11%	487
	11th to 20th	Day	8% 3 14% 37% 29% 9%	477
	21st to end	Day	9% 3 12% 36% 31% 9%	539
September	1st to 10th	Day	8% 4 18% 40% 25% 6%	490
	11th to 20th	Day	6% 2 31% 38% 20% 5%	485
	21st to end	Day	3 7% 35% 27% 22% 5%	300
October	1st to 10th	Day	10% 11% 30% 29% 15% 5%	300
	11th to 20th	Day	11% 15% 31% 26% 14% 3	300
	21st to end	Day	14% 19% 27% 22% 13% 5%	330
November	1st to 10th	Day	14% 28% 29% 18% 8% 3	300
	11th to 20th	Day	10% 20% 26% 26% 15% 3	300
	21st to end	Day	15% 31% 27% 19% 8% 1	300
December	1st to 10th	Day	18% 22% 29% 22% 9%	300
	11th to 20th	Day	13% 30% 26% 24% 6% 1	300
	21st to end	Day	24% 29% 26% 15% 5%	330
January	1st to 10th	Night	9% 18% 28% 31% 13% 2	800
	11th to 20th	Night	9% 20% 32% 27% 10% 2	800
	21st to end	Night	10% 19% 31% 28% 11% 1	880
February	1st to 10th	Night	10% 21% 31% 29% 9% 2	800
	11th to 20th	Night	10% 24% 37% 23% 5% 1	784
	21st to end	Night	14% 29% 34% 19% 3 1	660
March	1st to 10th	Night	13% 24% 28% 27% 7% 1	800
	11th to 20th	Night	13% 20% 29% 26% 12%	800
	21st to end	Night	10% 22% 36% 26% 6%	783
April	1st to 10th	Night	11% 25% 37% 23% 5%	600
	11th to 20th	Night	9% 28% 31% 25% 6%	593
	21st to end	Night	7% 25% 34% 28% 6%	600
May	1st to 10th	Night	4 19% 40% 32% 5%	600
	11th to 20th	Night	5% 16% 29% 34% 16% 1	591
	21st to end	Night	4 13% 35% 37% 11%	650
June	1st to 10th	Night	4 7% 27% 44% 18% 1	599
	11th to 20th	Night	3 6% 29% 45% 15% 1	570
	21st to end	Night	6% 4 16% 39% 31% 3	570
July	1st to 10th	Night	6% 1 12% 38% 38% 4	555
	11th to 20th	Night	4 1 5% 34% 48% 8%	552
	21st to end	Night	4 1 8% 27% 49% 11%	624
August	1st to 10th	Night	3 1 4 27% 52% 12%	567
	11th to 20th	Night	4 2 9% 30% 46% 10%	564
	21st to end	Night	3 2 9% 26% 50% 10%	627
September	1st to 10th	Night	7% 1 8% 35% 43% 6%	570
	11th to 20th	Night	7% 1 14% 40% 35% 3	570
	21st to end	Night	6% 3 17% 42% 29% 4	570
October	1st to 10th	Night	5% 9% 21% 39% 25% 3	744
	11th to 20th	Night	5% 8% 28% 39% 17% 3	760
	21st to end	Night	9% 14% 21% 29% 21% 6%	836
November	1st to 10th	Night	6% 14% 24% 33% 18% 4	780
	11th to 20th	Night	5% 14% 28% 35% 15% 3	985
	21st to end	Night	11% 18% 25% 27% 17% 2	1000
December	1st to 10th	Night	11% 18% 27% 32% 11% 2	1000
	11th to 20th	Night	12% 22% 30% 28% 8% 1	1000
	21st to end	Night	14% 20% 33% 25% 7% 1	1055

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