Wolf Creek Observing Site
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Wolf Creek Observing Site clear sky chart from 2005-11-06 to 2024-11-30.

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 8% 3 8% 5% 4 4 4 5% 6% 48%	105183
	Night	3 7% 3 7% 5% 4 4 4 5% 7% 51%	103167
Transparency	Day	31% 7% 11% 20% 19% 11%	104948
	Night	27% 8% 13% 22% 20% 10%	102991
Seeing	Day	13% 21% 33% 22% 9% 2	15274
	Night	8% 15% 28% 31% 15% 2	25586

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 7% 6% 17% 7% 6% 4 3 5% 7% 36%	2858
	11th to 20th	Day	1 10% 7% 18% 9% 6% 3 3 5% 5% 34%	2860
	21st to end	Day	2 15% 6% 10% 5% 3 3 2 3 6% 45%	3146
February	1st to 10th	Day	1 12% 6% 12% 6% 6% 5% 4 5% 5% 37%	1710
	11th to 20th	Day	3 14% 7% 10% 6% 3 5% 4 5% 7% 35%	1686
	21st to end	Day	2 13% 7% 15% 7% 5% 5% 3 4 6% 33%	1570
March	1st to 10th	Day	1 15% 9% 17% 5% 4 3 3 4 6% 33%	3426
	11th to 20th	Day	2 14% 5% 9% 6% 4 4 4 6% 7% 41%	3490
	21st to end	Day	4 21% 9% 15% 7% 5% 5% 4 4 5% 22%	3825
April	1st to 10th	Day	3 14% 4 11% 5% 4 4 4 6% 7% 38%	2143
	11th to 20th	Day	3 14% 5% 11% 6% 4 5% 3 6% 6% 35%	2335
	21st to end	Day	5% 12% 5% 9% 4 4 3 3 5% 6% 42%	2470
May	1st to 10th	Day	6% 13% 7% 12% 6% 5% 5% 4 5% 6% 33%	4110
	11th to 20th	Day	6% 8% 2 6% 4 4 4 4 6% 8% 48%	4071
	21st to end	Day	7% 10% 3 7% 5% 4 5% 4 6% 7% 43%	4504
June	1st to 10th	Day	5% 5% 2 5% 5% 4 4 4 5% 8% 53%	2660
	11th to 20th	Day	6% 4 2 5% 3 4 4 3 6% 5% 59%	2660
	21st to end	Day	3 4 2 4 3 4 3 4 5% 7% 62%	2620
July	1st to 10th	Day	4 3 1 4 3 3 3 3 4 5% 69%	4110
	11th to 20th	Day	5% 4 2 5% 5% 5% 6% 5% 8% 9% 46%	4110
	21st to end	Day	5% 4 1 5% 5% 4 4 4 6% 6% 55%	4454
August	1st to 10th	Day	4 3 2 5% 4 5% 5% 4 6% 7% 55%	4092
	11th to 20th	Day	3 3 1 4 4 4 5% 4 6% 7% 59%	4028
	21st to end	Day	5% 3 1 4 4 4 5% 4 5% 6% 59%	4411
September	1st to 10th	Day	7% 4 1 4 4 4 4 3 4 7% 59%	2204
	11th to 20th	Day	7% 5% 1 4 3 3 4 4 4 6% 57%	2090
	21st to end	Day	7% 5% 1 4 3 3 3 3 3 5% 64%	2090
October	1st to 10th	Day	6% 6% 1 4 3 2 2 3 4 5% 64%	3271
	11th to 20th	Day	6% 7% 2 6% 3 4 3 3 4 5% 55%	3150
	21st to end	Day	4 7% 3 5% 3 3 4 4 5% 6% 59%	3438
November	1st to 10th	Day	5% 10% 3 6% 4 4 3 3 6% 6% 50%	1813
	11th to 20th	Day	2 10% 3 6% 4 3 4 5% 5% 8% 50%	1773
	21st to end	Day	2 8% 3 9% 7% 4 4 4 5% 7% 47%	1596
December	1st to 10th	Day	2 11% 3 8% 7% 5% 5% 4 5% 8% 43%	1520
	11th to 20th	Day	2 12% 4 11% 7% 5% 5% 4 6% 6% 37%	1926
	21st to end	Day	2 9% 4 13% 6% 5% 4 3 5% 7% 44%	2963
January	1st to 10th	Night	2 6% 4 14% 10% 6% 4 3 5% 6% 41%	4097
	11th to 20th	Night	1 10% 6% 16% 10% 5% 4 3 5% 6% 32%	4110
	21st to end	Night	1 11% 5% 12% 7% 4 4 3 5% 7% 41%	4521
February	1st to 10th	Night	1 9% 5% 10% 7% 5% 4 4 6% 7% 42%	2470
	11th to 20th	Night	2 10% 4 8% 6% 5% 5% 4 6% 7% 43%	2379
	21st to end	Night	2 8% 4 10% 8% 5% 5% 4 6% 7% 40%	1884
March	1st to 10th	Night	1 10% 3 10% 7% 5% 6% 5% 6% 7% 40%	3447
	11th to 20th	Night	1 6% 3 7% 6% 5% 5% 4 6% 8% 50%	3490
	21st to end	Night	3 13% 4 13% 7% 5% 4 4 6% 5% 36%	3828
April	1st to 10th	Night	3 11% 3 6% 6% 4 4 4 5% 6% 49%	2035
	11th to 20th	Night	2 9% 3 7% 5% 5% 5% 5% 6% 8% 46%	1790
	21st to end	Night	4 9% 2 7% 4 4 4 4 6% 7% 49%	1710
May	1st to 10th	Night	3 10% 5% 8% 6% 5% 5% 4 5% 7% 41%	2860
	11th to 20th	Night	3 5% 2 4 3 3 4 4 6% 6% 60%	2834
	21st to end	Night	5% 7% 2 5% 4 4 5% 4 5% 8% 52%	3078
June	1st to 10th	Night	5% 4 2 5% 4 4 4 3 6% 8% 56%	1520
	11th to 20th	Night	4 3 1 5% 3 3 4 2 4 6% 63%	1520
	21st to end	Night	3 2 1 4 3 3 3 3 5% 6% 67%	1552
July	1st to 10th	Night	2 2 1 3 3 3 3 2 5% 5% 71%	2860
	11th to 20th	Night	3 3 1 5% 4 4 5% 5% 8% 10% 51%	2860
	21st to end	Night	3 2 1 4 5% 5% 5% 5% 7% 6% 57%	3109
August	1st to 10th	Night	4 2 1 4 4 4 4 4 6% 8% 59%	2847
	11th to 20th	Night	4 3 1 5% 4 4 5% 4 6% 7% 58%	2811
	21st to end	Night	2 3 2 4 3 3 3 3 4 6% 66%	3254
September	1st to 10th	Night	4 3 1 4 2 2 3 3 4 6% 66%	1971
	11th to 20th	Night	6% 3 1 3 3 2 3 3 5% 7% 63%	2090
	21st to end	Night	7% 4 1 3 2 2 2 2 3 5% 68%	2090
October	1st to 10th	Night	4 4 1 3 2 2 2 2 3 4 73%	3702
	11th to 20th	Night	4 4 1 4 4 3 4 4 6% 6% 60%	3778
	21st to end	Night	2 7% 2 5% 3 2 3 3 5% 8% 60%	4120
November	1st to 10th	Night	2 7% 3 6% 4 4 4 4 6% 7% 53%	2483
	11th to 20th	Night	1 7% 2 6% 5% 3 4 5% 6% 7% 54%	2605
	21st to end	Night	2 9% 3 8% 6% 4 3 4 5% 6% 51%	2800
December	1st to 10th	Night	2 9% 3 8% 5% 4 4 4 5% 8% 48%	2660
	11th to 20th	Night	2 12% 3 7% 6% 5% 5% 4 6% 9% 38%	3271
	21st to end	Night	1 8% 4 10% 6% 7% 6% 5% 5% 8% 40%	4731

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	37% 14% 16% 20% 12% 2	2859
	11th to 20th	Day	40% 17% 15% 16% 10% 2	2860
	21st to end	Day	38% 7% 20% 20% 13% 2	3146
February	1st to 10th	Day	42% 12% 14% 19% 10% 4	1710
	11th to 20th	Day	41% 10% 13% 22% 11% 3	1695
	21st to end	Day	46% 11% 12% 19% 11% 2	1570
March	1st to 10th	Day	46% 7% 13% 19% 11% 4	3426
	11th to 20th	Day	35% 10% 20% 25% 8% 2	3490
	21st to end	Day	56% 9% 15% 14% 5% 1	3825
April	1st to 10th	Day	37% 10% 16% 20% 14% 4	2143
	11th to 20th	Day	42% 10% 13% 21% 14% 1	2338
	21st to end	Day	39% 7% 12% 27% 13% 1	2470
May	1st to 10th	Day	36% 14% 11% 20% 16% 3	4110
	11th to 20th	Day	28% 7% 11% 34% 19% 2	4074
	21st to end	Day	32% 8% 11% 26% 21% 2	4504
June	1st to 10th	Day	27% 6% 11% 25% 26% 5%	2660
	11th to 20th	Day	24% 4 8% 19% 28% 16%	2660
	21st to end	Day	20% 5% 6% 14% 29% 26%	2620
July	1st to 10th	Day	17% 4 5% 9% 14% 52%	4046
	11th to 20th	Day	27% 5% 10% 15% 23% 20%	4041
	21st to end	Day	25% 6% 8% 12% 22% 27%	4314
August	1st to 10th	Day	25% 5% 10% 22% 21% 17%	4078
	11th to 20th	Day	22% 5% 9% 16% 30% 18%	4067
	21st to end	Day	23% 6% 7% 15% 26% 22%	4410
September	1st to 10th	Day	24% 5% 7% 16% 26% 22%	2204
	11th to 20th	Day	27% 5% 8% 18% 25% 17%	2090
	21st to end	Day	22% 5% 7% 21% 34% 11%	2090
October	1st to 10th	Day	23% 3 6% 17% 35% 15%	3271
	11th to 20th	Day	29% 3 9% 29% 25% 4	3150
	21st to end	Day	24% 4 12% 28% 27% 4	3438
November	1st to 10th	Day	32% 7% 14% 23% 21% 4	1813
	11th to 20th	Day	26% 7% 19% 25% 21% 2	1773
	21st to end	Day	31% 8% 14% 24% 17% 6%	1596
December	1st to 10th	Day	34% 12% 17% 20% 10% 5%	1520
	11th to 20th	Day	40% 9% 14% 20% 16% 1	1924
	21st to end	Day	37% 8% 13% 12% 20% 11%	2963
January	1st to 10th	Night	32% 18% 14% 17% 17% 2	4097
	11th to 20th	Night	44% 13% 14% 16% 11% 3	4110
	21st to end	Night	35% 9% 20% 22% 12% 3	4521
February	1st to 10th	Night	32% 13% 18% 22% 13% 3	2470
	11th to 20th	Night	32% 10% 16% 22% 19% 2	2380
	21st to end	Night	34% 10% 17% 21% 15% 4	1884
March	1st to 10th	Night	34% 8% 19% 22% 15% 4	3447
	11th to 20th	Night	26% 11% 18% 32% 10% 3	3490
	21st to end	Night	38% 11% 17% 21% 13% 2	3828
April	1st to 10th	Night	29% 10% 17% 21% 17% 6%	2035
	11th to 20th	Night	29% 8% 18% 27% 16% 2	1790
	21st to end	Night	29% 6% 18% 29% 17% 1	1710
May	1st to 10th	Night	29% 15% 11% 23% 19% 2	2860
	11th to 20th	Night	21% 6% 11% 33% 24% 5%	2835
	21st to end	Night	25% 6% 13% 31% 23% 2	3078
June	1st to 10th	Night	24% 6% 14% 24% 26% 6%	1520
	11th to 20th	Night	21% 5% 9% 17% 32% 17%	1520
	21st to end	Night	16% 4 4 18% 27% 30%	1552
July	1st to 10th	Night	15% 3 6% 10% 14% 52%	2815
	11th to 20th	Night	24% 4 8% 15% 25% 23%	2806
	21st to end	Night	24% 6% 11% 16% 21% 23%	3011
August	1st to 10th	Night	22% 4 12% 22% 22% 19%	2838
	11th to 20th	Night	25% 6% 9% 17% 25% 19%	2838
	21st to end	Night	17% 6% 10% 16% 27% 24%	3254
September	1st to 10th	Night	18% 4 8% 19% 27% 24%	1971
	11th to 20th	Night	19% 4 10% 22% 28% 17%	2090
	21st to end	Night	19% 4 6% 20% 38% 13%	2090
October	1st to 10th	Night	16% 3 7% 23% 34% 17%	3702
	11th to 20th	Night	22% 4 10% 32% 27% 6%	3778
	21st to end	Night	20% 5% 11% 33% 29% 3	4120
November	1st to 10th	Night	25% 7% 16% 23% 22% 6%	2483
	11th to 20th	Night	22% 7% 19% 29% 20% 3	2605
	21st to end	Night	29% 7% 12% 24% 20% 8%	2800
December	1st to 10th	Night	30% 10% 19% 23% 14% 5%	2660
	11th to 20th	Night	35% 10% 18% 21% 14% 2	3272
	21st to end	Night	35% 10% 16% 17% 13% 10%	4731

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	20% 22% 27% 20% 10% 1	270
	11th to 20th	Day	16% 27% 29% 19% 7% 1	270
	21st to end	Day	10% 30% 35% 19% 5% 1	297
February	1st to 10th	Day	23% 36% 31% 7% 3	270
	11th to 20th	Day	20% 34% 26% 14% 5% 1	291
	21st to end	Day	18% 35% 35% 10% 1 1	382
March	1st to 10th	Day	17% 34% 30% 14% 5%	460
	11th to 20th	Day	13% 30% 32% 22% 2 1	460
	21st to end	Day	16% 38% 34% 11% 1	506
April	1st to 10th	Day	22% 27% 28% 16% 5% 2	460
	11th to 20th	Day	22% 30% 32% 12% 4 1	452
	21st to end	Day	20% 27% 28% 19% 5% 1	460
May	1st to 10th	Day	20% 27% 33% 13% 7% 1	463
	11th to 20th	Day	16% 23% 32% 19% 8% 2	488
	21st to end	Day	16% 20% 31% 20% 11% 2	543
June	1st to 10th	Day	7% 15% 34% 26% 15% 3	680
	11th to 20th	Day	10% 21% 35% 21% 12% 1	680
	21st to end	Day	6% 14% 41% 25% 13% 2	640
July	1st to 10th	Day	5% 12% 37% 34% 11% 2	486
	11th to 20th	Day	6% 10% 42% 27% 11% 4	484
	21st to end	Day	6% 7% 37% 31% 15% 4	531
August	1st to 10th	Day	7% 10% 42% 28% 11% 3	487
	11th to 20th	Day	4 11% 37% 33% 12% 3	477
	21st to end	Day	7% 12% 33% 32% 12% 4	539
September	1st to 10th	Day	6% 13% 33% 28% 14% 5%	490
	11th to 20th	Day	10% 20% 32% 23% 13% 3	490
	21st to end	Day	12% 17% 27% 26% 15% 3	490
October	1st to 10th	Day	12% 19% 27% 22% 16% 4	362
	11th to 20th	Day	15% 21% 25% 22% 15% 2	300
	21st to end	Day	15% 24% 31% 22% 8% 1	330
November	1st to 10th	Day	17% 26% 26% 19% 11% 1	300
	11th to 20th	Day	14% 19% 37% 20% 7% 3	300
	21st to end	Day	14% 17% 33% 24% 10% 2	299
December	1st to 10th	Day	12% 24% 33% 21% 8% 3	270
	11th to 20th	Day	10% 29% 32% 24% 4 1	270
	21st to end	Day	18% 30% 27% 20% 5% 1	297
January	1st to 10th	Night	10% 19% 29% 28% 12% 2	760
	11th to 20th	Night	9% 19% 32% 28% 10% 2	760
	21st to end	Night	5% 21% 34% 28% 9% 2	836
February	1st to 10th	Night	11% 25% 36% 19% 8% 2	760
	11th to 20th	Night	8% 24% 34% 24% 9% 1	744
	21st to end	Night	9% 24% 36% 25% 6%	628
March	1st to 10th	Night	9% 20% 33% 29% 7% 2	760
	11th to 20th	Night	7% 15% 31% 33% 14% 1	760
	21st to end	Night	9% 23% 33% 26% 7% 1	836
April	1st to 10th	Night	10% 23% 31% 26% 9% 1	705
	11th to 20th	Night	10% 20% 34% 28% 8%	563
	21st to end	Night	11% 21% 30% 25% 11% 1	570
May	1st to 10th	Night	8% 18% 34% 28% 11% 1	570
	11th to 20th	Night	7% 7% 28% 38% 17% 3	561
	21st to end	Night	10% 14% 26% 30% 18% 2	617
June	1st to 10th	Night	6% 11% 26% 36% 19% 2	570
	11th to 20th	Night	8% 13% 31% 35% 13% 1	570
	21st to end	Night	3 5% 28% 39% 22% 2	570
July	1st to 10th	Night	5% 4 18% 38% 32% 3	555
	11th to 20th	Night	7% 2 16% 43% 29% 3	552
	21st to end	Night	4 1 11% 44% 38% 3	624
August	1st to 10th	Night	6% 3 13% 48% 28% 2	567
	11th to 20th	Night	6% 3 16% 42% 29% 4	564
	21st to end	Night	4 3 17% 43% 30% 3	627
September	1st to 10th	Night	5% 4 20% 35% 30% 5%	641
	11th to 20th	Night	5% 6% 21% 35% 28% 6%	760
	21st to end	Night	8% 9% 18% 34% 24% 7%	760
October	1st to 10th	Night	8% 13% 27% 31% 19% 3	760
	11th to 20th	Night	6% 16% 23% 35% 17% 3	760
	21st to end	Night	6% 17% 27% 32% 15% 3	836
November	1st to 10th	Night	7% 16% 30% 31% 14% 2	780
	11th to 20th	Night	6% 21% 31% 28% 11% 3	805
	21st to end	Night	10% 19% 28% 31% 10% 3	1000
December	1st to 10th	Night	9% 19% 35% 28% 8% 1	950
	11th to 20th	Night	8% 20% 35% 28% 8% 1	950
	21st to end	Night	10% 23% 37% 23% 6% 1	955

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