Bearcat Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bearcat Observatory clear sky chart from 2005-11-06 to 2024-10-20.

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% 7% 3 7% 4 4 4 4 5% 7% 43%	101035
	Night	11% 7% 3 7% 4 4 4 3 5% 6% 47%	97722
Transparency	Day	40% 6% 13% 25% 14% 2	100846
	Night	38% 5% 12% 25% 17% 3	97583
Seeing	Day	14% 9% 29% 29% 15% 4	15716
	Night	14% 9% 33% 32% 11% 1	25532

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	11% 11% 4 13% 9% 5% 5% 4 5% 6% 26%	2818
	11th to 20th	Day	9% 13% 5% 10% 5% 5% 7% 3 4 6% 32%	2850
	21st to end	Day	12% 14% 6% 16% 7% 6% 4 3 4 5% 24%	3135
February	1st to 10th	Day	11% 12% 4 8% 6% 6% 5% 4 5% 7% 32%	1710
	11th to 20th	Day	11% 9% 4 6% 4 5% 4 4 7% 7% 39%	1664
	21st to end	Day	11% 10% 3 6% 6% 4 3 3 5% 7% 42%	1576
March	1st to 10th	Day	15% 10% 3 6% 4 3 3 3 3 5% 45%	3436
	11th to 20th	Day	11% 8% 3 6% 4 3 4 3 5% 7% 48%	3480
	21st to end	Day	19% 13% 6% 8% 4 4 4 4 5% 7% 26%	3814
April	1st to 10th	Day	15% 8% 3 6% 5% 3 3 3 4 6% 44%	2203
	11th to 20th	Day	15% 9% 3 7% 5% 3 4 4 6% 6% 39%	2254
	21st to end	Day	21% 7% 2 6% 4 3 4 4 5% 7% 37%	2460
May	1st to 10th	Day	15% 8% 3 7% 5% 4 5% 4 6% 8% 36%	4082
	11th to 20th	Day	16% 7% 3 6% 5% 4 4 4 5% 6% 40%	4082
	21st to end	Day	13% 7% 2 6% 4 4 4 3 5% 8% 44%	4762
June	1st to 10th	Day	7% 5% 1 6% 5% 4 5% 5% 6% 9% 48%	2660
	11th to 20th	Day	8% 5% 2 5% 4 4 4 4 7% 9% 47%	2660
	21st to end	Day	8% 6% 1 5% 5% 5% 5% 5% 6% 9% 46%	2660
July	1st to 10th	Day	12% 5% 3 6% 4 4 5% 4 7% 9% 40%	4328
	11th to 20th	Day	7% 4 1 4 3 4 4 4 6% 8% 54%	4120
	21st to end	Day	4 3 1 4 4 3 4 4 7% 11% 54%	4465
August	1st to 10th	Day	6% 4 2 5% 4 4 5% 3 7% 10% 49%	4104
	11th to 20th	Day	11% 6% 2 6% 4 4 5% 4 6% 8% 43%	4041
	21st to end	Day	6% 5% 2 7% 4 5% 5% 4 6% 7% 50%	4318
September	1st to 10th	Day	11% 4 2 4 4 3 3 3 6% 6% 54%	2280
	11th to 20th	Day	9% 4 2 6% 4 4 4 3 5% 8% 51%	2115
	21st to end	Day	11% 4 1 5% 3 3 4 3 5% 6% 56%	2076
October	1st to 10th	Day	13% 6% 2 5% 4 3 3 3 4 6% 51%	1900
	11th to 20th	Day	12% 8% 2 4 3 3 2 3 3 5% 55%	1890
	21st to end	Day	13% 8% 3 6% 4 3 4 3 6% 5% 46%	1980
November	1st to 10th	Day	9% 7% 2 5% 3 3 2 2 5% 8% 53%	1803
	11th to 20th	Day	11% 9% 2 7% 4 4 4 2 4 6% 48%	1568
	21st to end	Day	14% 9% 4 6% 3 3 3 4 6% 6% 41%	1520
December	1st to 10th	Day	9% 7% 3 8% 6% 4 4 4 5% 7% 44%	1520
	11th to 20th	Day	10% 11% 4 9% 6% 4 4 3 6% 6% 38%	1918
	21st to end	Day	18% 12% 6% 15% 6% 4 4 4 5% 4 23%	2783
January	1st to 10th	Night	8% 8% 4 18% 7% 6% 5% 3 5% 6% 30%	4135
	11th to 20th	Night	10% 10% 4 8% 4 5% 7% 4 7% 5% 35%	4120
	21st to end	Night	13% 14% 5% 13% 5% 5% 4 3 4 5% 30%	4532
February	1st to 10th	Night	12% 10% 3 9% 5% 4 4 3 6% 5% 38%	2470
	11th to 20th	Night	11% 9% 3 7% 4 4 3 4 5% 6% 44%	2403
	21st to end	Night	10% 8% 3 7% 4 4 3 3 5% 5% 47%	1894
March	1st to 10th	Night	12% 6% 2 6% 4 3 4 3 4 5% 50%	3419
	11th to 20th	Night	12% 5% 2 5% 3 3 3 2 4 5% 55%	3480
	21st to end	Night	19% 10% 3 10% 4 4 4 3 5% 6% 31%	3817
April	1st to 10th	Night	10% 8% 2 6% 3 4 4 3 6% 7% 48%	1976
	11th to 20th	Night	13% 8% 2 7% 4 4 3 4 5% 6% 46%	1875
	21st to end	Night	16% 9% 3 5% 4 3 4 3 5% 5% 44%	1716
May	1st to 10th	Night	15% 7% 2 6% 4 4 4 3 5% 7% 43%	2823
	11th to 20th	Night	13% 7% 2 6% 4 4 3 2 4 6% 49%	2823
	21st to end	Night	13% 6% 2 6% 4 4 3 3 5% 7% 48%	2789
June	1st to 10th	Night	6% 3 2 4 4 3 4 5% 6% 8% 55%	1520
	11th to 20th	Night	6% 3 1 4 3 3 5% 4 8% 11% 51%	1520
	21st to end	Night	5% 4 1 3 3 4 4 3 7% 10% 57%	1520
July	1st to 10th	Night	10% 5% 2 6% 4 4 4 4 6% 8% 47%	2623
	11th to 20th	Night	4 3 1 4 3 3 3 3 6% 8% 63%	2850
	21st to end	Night	5% 3 2 4 4 4 4 4 8% 10% 53%	3098
August	1st to 10th	Night	3 2 1 4 3 3 4 3 6% 10% 61%	2836
	11th to 20th	Night	13% 6% 2 5% 3 3 3 2 4 6% 53%	2798
	21st to end	Night	6% 3 2 5% 3 3 3 3 5% 8% 58%	3342
September	1st to 10th	Night	10% 3 1 3 4 3 3 3 5% 7% 57%	1900
	11th to 20th	Night	10% 3 2 4 4 4 3 3 4 7% 56%	2061
	21st to end	Night	9% 4 1 5% 3 2 3 3 4 6% 59%	2090
October	1st to 10th	Night	13% 6% 1 4 3 3 3 3 5% 6% 54%	2275
	11th to 20th	Night	13% 7% 2 4 2 3 3 2 4 5% 56%	2275
	21st to end	Night	16% 6% 2 5% 3 3 3 2 4 5% 51%	2376
November	1st to 10th	Night	8% 3 1 4 3 3 4 3 5% 7% 58%	2272
	11th to 20th	Night	10% 6% 2 5% 5% 3 3 3 5% 7% 50%	2611
	21st to end	Night	14% 8% 3 4 3 3 3 3 5% 5% 49%	2660
December	1st to 10th	Night	10% 8% 3 6% 5% 5% 4 3 6% 6% 44%	2660
	11th to 20th	Night	12% 9% 3 8% 4 3 3 3 4 5% 46%	3279
	21st to end	Night	19% 16% 7% 12% 5% 3 3 3 3 4 26%	4884

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	56% 6% 13% 15% 8% 1	2819
	11th to 20th	Day	54% 5% 13% 19% 9%	2850
	21st to end	Day	62% 5% 11% 14% 7%	3135
February	1st to 10th	Day	50% 6% 12% 19% 10% 2	1710
	11th to 20th	Day	43% 6% 13% 23% 13% 2	1673
	21st to end	Day	42% 4 13% 23% 15% 2	1576
March	1st to 10th	Day	42% 5% 10% 21% 20% 2	3436
	11th to 20th	Day	37% 6% 11% 26% 19% 2	3480
	21st to end	Day	56% 8% 17% 14% 4 1	3814
April	1st to 10th	Day	42% 5% 11% 26% 14% 2	2203
	11th to 20th	Day	44% 5% 12% 22% 14% 2	2254
	21st to end	Day	47% 7% 10% 25% 11% 1	2460
May	1st to 10th	Day	43% 8% 13% 22% 13% 2	4120
	11th to 20th	Day	44% 7% 11% 25% 14%	4086
	21st to end	Day	37% 7% 12% 26% 16% 2	4775
June	1st to 10th	Day	31% 9% 15% 28% 14% 3	2660
	11th to 20th	Day	33% 7% 14% 28% 17% 2	2660
	21st to end	Day	32% 8% 15% 27% 14% 3	2660
July	1st to 10th	Day	39% 4 16% 27% 12% 2	4262
	11th to 20th	Day	28% 5% 11% 34% 20% 2	4051
	21st to end	Day	23% 5% 19% 34% 15% 3	4325
August	1st to 10th	Day	29% 5% 15% 31% 18% 1	4090
	11th to 20th	Day	38% 5% 16% 26% 16%	4080
	21st to end	Day	33% 4 16% 29% 14% 4	4317
September	1st to 10th	Day	30% 6% 11% 29% 20% 5%	2280
	11th to 20th	Day	32% 6% 12% 28% 21% 2	2115
	21st to end	Day	29% 5% 9% 31% 24% 2	2076
October	1st to 10th	Day	36% 4 10% 26% 23% 1	1900
	11th to 20th	Day	33% 4 8% 26% 23% 5%	1890
	21st to end	Day	38% 5% 11% 24% 16% 5%	1980
November	1st to 10th	Day	31% 4 15% 27% 20% 3	1803
	11th to 20th	Day	38% 3 12% 27% 17% 2	1568
	21st to end	Day	42% 5% 12% 26% 15% 1	1520
December	1st to 10th	Day	39% 7% 15% 25% 12% 1	1520
	11th to 20th	Day	46% 5% 17% 26% 5% 1	1915
	21st to end	Day	64% 5% 10% 15% 6% 1	2783
January	1st to 10th	Night	53% 6% 11% 19% 10% 1	4135
	11th to 20th	Night	47% 5% 12% 24% 11% 1	4120
	21st to end	Night	57% 5% 14% 15% 8% 1	4532
February	1st to 10th	Night	47% 5% 12% 19% 14% 3	2470
	11th to 20th	Night	41% 5% 12% 23% 17% 2	2404
	21st to end	Night	39% 4 11% 21% 19% 5%	1894
March	1st to 10th	Night	36% 5% 10% 25% 21% 2	3419
	11th to 20th	Night	32% 5% 8% 31% 18% 5%	3480
	21st to end	Night	53% 7% 18% 17% 4 1	3817
April	1st to 10th	Night	34% 7% 11% 27% 18% 3	1976
	11th to 20th	Night	39% 7% 9% 27% 15% 3	1875
	21st to end	Night	42% 6% 10% 25% 16% 2	1716
May	1st to 10th	Night	39% 8% 11% 21% 19% 2	2850
	11th to 20th	Night	37% 6% 10% 25% 20% 1	2824
	21st to end	Night	36% 7% 13% 24% 19% 3	2797
June	1st to 10th	Night	23% 9% 18% 30% 16% 4	1520
	11th to 20th	Night	24% 8% 16% 29% 20% 4	1520
	21st to end	Night	22% 7% 18% 30% 18% 4	1520
July	1st to 10th	Night	36% 4 13% 25% 18% 4	2581
	11th to 20th	Night	21% 4 15% 35% 22% 2	2796
	21st to end	Night	25% 5% 19% 31% 19% 1	2999
August	1st to 10th	Night	20% 5% 16% 33% 24% 2	2826
	11th to 20th	Night	34% 3 13% 28% 20% 1	2825
	21st to end	Night	26% 4 17% 30% 18% 6%	3342
September	1st to 10th	Night	27% 6% 10% 26% 24% 7%	1900
	11th to 20th	Night	28% 5% 10% 32% 22% 3	2061
	21st to end	Night	27% 5% 8% 31% 26% 3	2090
October	1st to 10th	Night	32% 4 9% 26% 25% 4	2275
	11th to 20th	Night	32% 4 8% 25% 24% 7%	2275
	21st to end	Night	36% 5% 10% 23% 23% 3	2376
November	1st to 10th	Night	25% 5% 15% 26% 24% 5%	2272
	11th to 20th	Night	33% 4 10% 30% 19% 3	2611
	21st to end	Night	37% 5% 10% 28% 18% 2	2660
December	1st to 10th	Night	40% 5% 13% 28% 13% 1	2660
	11th to 20th	Night	42% 4 12% 31% 10% 1	3281
	21st to end	Night	63% 4 8% 17% 8% 1	4884

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% 13% 35% 23% 8%	270
	11th to 20th	Day	21% 19% 35% 21% 5%	270
	21st to end	Day	16% 10% 43% 26% 4	297
February	1st to 10th	Day	16% 18% 43% 20% 3 1	270
	11th to 20th	Day	13% 19% 40% 20% 6%	270
	21st to end	Day	15% 19% 45% 19% 2	225
March	1st to 10th	Day	19% 15% 42% 22% 2 1	270
	11th to 20th	Day	28% 11% 34% 23% 3 1	270
	21st to end	Day	33% 21% 28% 13% 4	297
April	1st to 10th	Day	25% 13% 37% 19% 5% 1	383
	11th to 20th	Day	19% 16% 35% 23% 7%	452
	21st to end	Day	23% 17% 33% 18% 7% 1	640
May	1st to 10th	Day	18% 14% 33% 26% 8% 1	653
	11th to 20th	Day	18% 11% 31% 26% 12% 2	675
	21st to end	Day	18% 9% 27% 27% 16% 2	734
June	1st to 10th	Day	7% 4 23% 34% 24% 7%	680
	11th to 20th	Day	8% 5% 28% 36% 19% 4	680
	21st to end	Day	8% 6% 36% 32% 14% 3	680
July	1st to 10th	Day	9% 3 17% 32% 28% 11%	671
	11th to 20th	Day	7% 3 21% 37% 25% 7%	668
	21st to end	Day	6% 2 15% 42% 29% 6%	739
August	1st to 10th	Day	8% 2 19% 41% 25% 6%	676
	11th to 20th	Day	10% 3 20% 36% 26% 5%	665
	21st to end	Day	8% 3 19% 33% 29% 8%	625
September	1st to 10th	Day	13% 4 22% 30% 26% 6%	490
	11th to 20th	Day	8% 3 21% 39% 21% 8%	325
	21st to end	Day	14% 6% 29% 30% 18% 3	300
October	1st to 10th	Day	17% 8% 27% 28% 13% 7%	300
	11th to 20th	Day	11% 21% 39% 22% 6% 1	297
	21st to end	Day	17% 18% 32% 24% 7% 2	297
November	1st to 10th	Day	13% 12% 40% 25% 8% 2	270
	11th to 20th	Day	18% 14% 39% 21% 7% 1	270
	21st to end	Day	23% 11% 36% 22% 8%	270
December	1st to 10th	Day	8% 18% 39% 27% 6% 2	270
	11th to 20th	Day	18% 15% 34% 25% 7% 1	270
	21st to end	Day	22% 19% 40% 17% 2	297
January	1st to 10th	Night	11% 13% 39% 29% 7%	950
	11th to 20th	Night	15% 14% 38% 26% 6%	950
	21st to end	Night	14% 12% 41% 28% 5%	1045
February	1st to 10th	Night	17% 11% 42% 26% 4	950
	11th to 20th	Night	16% 12% 41% 27% 5%	929
	21st to end	Night	15% 16% 42% 20% 6% 1	638
March	1st to 10th	Night	14% 14% 41% 26% 5%	570
	11th to 20th	Night	21% 9% 36% 28% 6%	570
	21st to end	Night	27% 12% 37% 19% 5%	627
April	1st to 10th	Night	15% 14% 40% 26% 5%	570
	11th to 20th	Night	16% 13% 39% 25% 6%	563
	21st to end	Night	20% 11% 35% 28% 5% 1	570
May	1st to 10th	Night	15% 11% 36% 33% 6% 1	570
	11th to 20th	Night	16% 9% 32% 30% 11% 1	561
	21st to end	Night	13% 8% 29% 35% 13% 1	617
June	1st to 10th	Night	5% 4 25% 44% 21% 1	570
	11th to 20th	Night	9% 3 26% 44% 17%	570
	21st to end	Night	5% 3 33% 43% 15% 1	570
July	1st to 10th	Night	7% 2 16% 43% 30% 3	555
	11th to 20th	Night	5% 1 16% 48% 28% 2	552
	21st to end	Night	5% 2 16% 47% 28% 2	624
August	1st to 10th	Night	4 1 21% 47% 25% 1	567
	11th to 20th	Night	9% 2 14% 47% 25% 2	564
	21st to end	Night	9% 2 16% 42% 29% 3	627
September	1st to 10th	Night	11% 2 21% 40% 24% 2	570
	11th to 20th	Night	12% 3 20% 40% 24% 1	570
	21st to end	Night	10% 4 29% 41% 16% 1	570
October	1st to 10th	Night	15% 7% 28% 33% 15% 2	755
	11th to 20th	Night	17% 8% 39% 28% 8%	759
	21st to end	Night	19% 10% 36% 28% 7%	792
November	1st to 10th	Night	9% 11% 35% 36% 9%	792
	11th to 20th	Night	13% 14% 39% 28% 6%	950
	21st to end	Night	18% 10% 35% 28% 8%	950
December	1st to 10th	Night	15% 12% 38% 28% 6% 1	950
	11th to 20th	Night	19% 9% 36% 30% 7%	950
	21st to end	Night	20% 14% 38% 24% 4	1045

Page generated at 2024-10-17 12:09:43. Version ac07

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