Cosmic Orchard Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cosmic Orchard Observatory clear sky chart from 2005-11-06 to 2024-08-30.

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	16% 12% 4 8% 5% 4 4 4 5% 7% 31%	95626
	Night	16% 13% 4 9% 5% 4 4 3 5% 6% 31%	93318
Transparency	Day	53% 4 11% 20% 11% 1	95397
	Night	54% 4 11% 19% 11% 2	93152
Seeing	Day	22% 12% 28% 22% 12% 5%	14688
	Night	22% 10% 26% 27% 12% 1	24225

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	19% 24% 7% 14% 5% 4 3 2 4 4 14%	2836
	11th to 20th	Day	16% 24% 8% 13% 6% 5% 6% 3 4 4 11%	2840
	21st to end	Day	27% 21% 11% 13% 7% 4 2 2 2 3 8%	3124
February	1st to 10th	Day	17% 20% 5% 11% 6% 4 4 3 4 4 21%	1710
	11th to 20th	Day	14% 15% 7% 16% 8% 5% 4 4 4 5% 20%	1739
	21st to end	Day	18% 14% 4 13% 6% 4 4 4 5% 6% 22%	1570
March	1st to 10th	Day	22% 15% 6% 8% 4 4 3 3 4 7% 25%	3330
	11th to 20th	Day	13% 15% 5% 11% 5% 4 4 2 4 5% 33%	3480
	21st to end	Day	21% 13% 6% 9% 4 3 3 3 4 6% 29%	3815
April	1st to 10th	Day	15% 14% 4 7% 5% 4 4 4 5% 6% 31%	2109
	11th to 20th	Day	18% 12% 3 6% 4 5% 5% 3 5% 6% 33%	2442
	21st to end	Day	21% 11% 3 7% 3 4 4 3 5% 6% 33%	2470
May	1st to 10th	Day	19% 9% 3 8% 5% 4 5% 4 6% 6% 31%	4082
	11th to 20th	Day	18% 9% 3 6% 4 4 4 4 6% 7% 35%	4081
	21st to end	Day	10% 7% 3 7% 5% 5% 5% 5% 7% 9% 39%	4476
June	1st to 10th	Day	14% 7% 2 6% 5% 5% 5% 4 7% 9% 37%	2631
	11th to 20th	Day	12% 6% 3 7% 5% 5% 5% 4 6% 8% 39%	2696
	21st to end	Day	11% 6% 1 5% 5% 4 5% 5% 8% 9% 40%	2774
July	1st to 10th	Day	10% 6% 3 8% 5% 4 5% 4 7% 10% 39%	4326
	11th to 20th	Day	9% 5% 2 6% 4 4 5% 4 7% 10% 44%	4120
	21st to end	Day	10% 6% 3 7% 5% 5% 5% 4 7% 8% 40%	4466
August	1st to 10th	Day	9% 6% 2 6% 5% 5% 6% 5% 7% 9% 40%	2457
	11th to 20th	Day	11% 7% 2 7% 5% 5% 5% 5% 7% 10% 37%	2433
	21st to end	Day	11% 6% 2 6% 4 5% 5% 4 7% 10% 40%	2672
September	1st to 10th	Day	14% 6% 2 5% 5% 5% 5% 5% 6% 9% 39%	2036
	11th to 20th	Day	12% 6% 3 7% 5% 4 4 4 5% 8% 42%	1980
	21st to end	Day	17% 8% 3 7% 4 3 3 3 6% 8% 38%	1980
October	1st to 10th	Day	15% 7% 3 7% 5% 3 5% 4 6% 9% 37%	1877
	11th to 20th	Day	19% 10% 3 7% 4 4 4 4 5% 6% 35%	1800
	21st to end	Day	23% 12% 3 8% 5% 3 5% 3 5% 5% 27%	1949
November	1st to 10th	Day	13% 12% 4 7% 5% 4 4 3 5% 6% 36%	1672
	11th to 20th	Day	18% 17% 4 8% 4 3 4 3 4 6% 28%	1710
	21st to end	Day	18% 19% 6% 9% 6% 5% 4 3 4 6% 19%	1535
December	1st to 10th	Day	17% 23% 6% 11% 7% 4 4 2 4 5% 17%	1520
	11th to 20th	Day	18% 19% 7% 15% 5% 4 4 3 5% 6% 16%	1910
	21st to end	Day	24% 24% 8% 11% 5% 4 3 3 4 4 10%	2978
January	1st to 10th	Night	16% 24% 10% 13% 6% 4 3 3 4 4 15%	4109
	11th to 20th	Night	14% 21% 10% 18% 6% 4 6% 4 3 3 10%	4120
	21st to end	Night	27% 20% 7% 14% 5% 3 3 2 3 3 14%	4532
February	1st to 10th	Night	20% 15% 5% 13% 6% 4 3 3 4 5% 21%	2470
	11th to 20th	Night	17% 16% 6% 11% 6% 5% 5% 4 4 5% 22%	2323
	21st to end	Night	19% 14% 6% 12% 6% 5% 4 2 4 4 23%	1884
March	1st to 10th	Night	21% 15% 4 7% 4 3 3 3 4 5% 33%	3523
	11th to 20th	Night	15% 11% 3 7% 4 5% 4 4 5% 6% 35%	3480
	21st to end	Night	18% 12% 5% 8% 4 4 4 3 5% 5% 33%	3817
April	1st to 10th	Night	16% 14% 3 8% 5% 4 4 4 5% 6% 31%	2071
	11th to 20th	Night	16% 10% 3 7% 5% 5% 5% 4 5% 7% 33%	1702
	21st to end	Night	16% 9% 3 8% 4 4 4 4 6% 5% 37%	1710
May	1st to 10th	Night	21% 10% 4 8% 5% 4 5% 3 5% 7% 28%	2813
	11th to 20th	Night	16% 9% 3 6% 4 4 4 4 6% 7% 37%	2812
	21st to end	Night	10% 5% 2 4 4 4 5% 4 6% 9% 46%	3079
June	1st to 10th	Night	10% 6% 2 6% 5% 5% 5% 4 6% 6% 44%	1544
	11th to 20th	Night	9% 5% 3 8% 4 5% 6% 4 8% 9% 40%	1474
	21st to end	Night	10% 6% 2 5% 5% 5% 5% 3 6% 10% 43%	1397
July	1st to 10th	Night	10% 6% 2 6% 3 4 4 4 6% 9% 47%	2623
	11th to 20th	Night	9% 4 2 5% 4 4 5% 5% 6% 9% 48%	2840
	21st to end	Night	7% 6% 2 6% 5% 5% 5% 4 7% 9% 44%	3087
August	1st to 10th	Night	8% 5% 3 6% 4 4 5% 4 6% 9% 47%	1701
	11th to 20th	Night	9% 6% 3 7% 5% 4 4 3 7% 8% 44%	1688
	21st to end	Night	8% 5% 3 6% 4 5% 5% 4 6% 8% 45%	1873
September	1st to 10th	Night	11% 7% 2 6% 4 5% 5% 4 5% 7% 44%	1920
	11th to 20th	Night	11% 4 2 5% 4 4 4 3 6% 8% 49%	1980
	21st to end	Night	14% 7% 2 7% 4 5% 4 3 5% 7% 40%	1980
October	1st to 10th	Night	14% 6% 2 6% 4 4 4 3 6% 7% 43%	2082
	11th to 20th	Night	20% 9% 3 7% 5% 4 4 3 5% 6% 34%	2160
	21st to end	Night	26% 10% 3 7% 4 4 4 3 5% 5% 28%	2402
November	1st to 10th	Night	15% 11% 4 6% 4 4 4 4 6% 6% 36%	2406
	11th to 20th	Night	17% 18% 4 7% 6% 4 3 3 5% 5% 28%	2470
	21st to end	Night	22% 17% 4 8% 5% 4 4 3 4 6% 22%	2641
December	1st to 10th	Night	20% 20% 7% 10% 5% 4 3 3 4 5% 19%	2660
	11th to 20th	Night	17% 20% 6% 11% 5% 4 4 3 5% 5% 21%	3285
	21st to end	Night	24% 22% 7% 10% 5% 4 4 3 4 5% 12%	4660

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	76% 2 10% 10% 2	2837
	11th to 20th	Day	78% 2 9% 9% 2	2840
	21st to end	Day	85% 2 5% 5% 3	3124
February	1st to 10th	Day	67% 3 10% 13% 6%	1710
	11th to 20th	Day	67% 5% 6% 15% 6% 1	1748
	21st to end	Day	62% 4 11% 14% 7% 1	1570
March	1st to 10th	Day	62% 2 9% 23% 5%	3330
	11th to 20th	Day	55% 3 12% 22% 7% 1	3480
	21st to end	Day	59% 3 11% 17% 10% 1	3815
April	1st to 10th	Day	53% 4 10% 19% 13% 1	2109
	11th to 20th	Day	51% 4 10% 18% 14% 2	2442
	21st to end	Day	52% 3 11% 22% 11% 2	2470
May	1st to 10th	Day	53% 4 9% 23% 10% 1	4120
	11th to 20th	Day	48% 4 12% 24% 10% 1	4085
	21st to end	Day	40% 5% 13% 21% 16% 5%	4489
June	1st to 10th	Day	44% 4 10% 26% 14% 1	2631
	11th to 20th	Day	41% 5% 14% 23% 15% 2	2696
	21st to end	Day	37% 7% 13% 24% 16% 2	2774
July	1st to 10th	Day	40% 5% 11% 24% 18% 2	4260
	11th to 20th	Day	33% 6% 12% 29% 19% 2	4051
	21st to end	Day	40% 6% 14% 19% 20% 2	4324
August	1st to 10th	Day	39% 6% 12% 28% 14% 1	2444
	11th to 20th	Day	40% 6% 14% 26% 12% 2	2433
	21st to end	Day	38% 6% 12% 25% 16% 3	2672
September	1st to 10th	Day	40% 6% 14% 21% 16% 3	2036
	11th to 20th	Day	40% 4 13% 26% 15% 2	1980
	21st to end	Day	44% 4 10% 24% 18% 1	1980
October	1st to 10th	Day	44% 6% 10% 24% 15% 1	1877
	11th to 20th	Day	50% 4 11% 22% 12% 2	1800
	21st to end	Day	59% 4 12% 15% 9% 1	1949
November	1st to 10th	Day	49% 4 10% 22% 14% 1	1672
	11th to 20th	Day	58% 3 9% 18% 9% 2	1710
	21st to end	Day	67% 4 9% 14% 6%	1535
December	1st to 10th	Day	72% 3 10% 12% 3	1520
	11th to 20th	Day	72% 2 8% 14% 3	1906
	21st to end	Day	80% 3 9% 7% 2	2978
January	1st to 10th	Night	75% 3 7% 12% 4	4109
	11th to 20th	Night	82% 3 6% 8% 1	4120
	21st to end	Night	78% 2 7% 10% 3	4532
February	1st to 10th	Night	67% 3 9% 14% 5% 1	2470
	11th to 20th	Night	65% 4 7% 17% 7%	2325
	21st to end	Night	65% 3 9% 14% 7% 2	1884
March	1st to 10th	Night	56% 2 10% 23% 8%	3523
	11th to 20th	Night	49% 5% 14% 20% 11% 1	3480
	21st to end	Night	53% 3 7% 25% 10% 1	3817
April	1st to 10th	Night	53% 4 11% 17% 13% 2	2071
	11th to 20th	Night	50% 4 11% 17% 15% 3	1702
	21st to end	Night	47% 4 11% 21% 14% 3	1710
May	1st to 10th	Night	55% 4 9% 20% 10% 2	2840
	11th to 20th	Night	47% 3 11% 24% 13% 2	2813
	21st to end	Night	33% 4 14% 27% 18% 4	3087
June	1st to 10th	Night	41% 5% 10% 26% 15% 3	1544
	11th to 20th	Night	38% 5% 15% 20% 18% 3	1474
	21st to end	Night	36% 5% 13% 26% 17% 2	1397
July	1st to 10th	Night	34% 5% 12% 24% 18% 6%	2580
	11th to 20th	Night	32% 5% 13% 28% 18% 3	2786
	21st to end	Night	34% 7% 13% 20% 23% 2	2988
August	1st to 10th	Night	32% 6% 14% 28% 19% 1	1690
	11th to 20th	Night	37% 5% 16% 27% 13% 2	1688
	21st to end	Night	37% 4 12% 27% 17% 3	1873
September	1st to 10th	Night	39% 4 13% 25% 15% 4	1920
	11th to 20th	Night	33% 4 11% 28% 22% 2	1980
	21st to end	Night	44% 3 11% 22% 19% 1	1980
October	1st to 10th	Night	40% 4 12% 24% 19% 1	2082
	11th to 20th	Night	51% 4 10% 21% 13% 1	2160
	21st to end	Night	58% 3 9% 18% 9% 1	2402
November	1st to 10th	Night	48% 3 11% 22% 13% 2	2406
	11th to 20th	Night	59% 2 8% 19% 9% 2	2470
	21st to end	Night	64% 3 11% 16% 5%	2641
December	1st to 10th	Night	69% 3 10% 12% 5%	2660
	11th to 20th	Night	66% 3 12% 16% 3	3288
	21st to end	Night	77% 2 11% 8% 2	4660

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	30% 20% 31% 13% 6% 1	270
	11th to 20th	Day	31% 24% 32% 9% 3 1	270
	21st to end	Day	31% 22% 32% 12% 2 1	297
February	1st to 10th	Day	32% 20% 36% 10% 3	270
	11th to 20th	Day	29% 26% 33% 10% 2	270
	21st to end	Day	32% 29% 32% 7%	225
March	1st to 10th	Day	28% 20% 30% 16% 5%	389
	11th to 20th	Day	27% 13% 37% 17% 5% 1	460
	21st to end	Day	33% 16% 28% 18% 6%	506
April	1st to 10th	Day	26% 14% 34% 18% 7% 1	460
	11th to 20th	Day	28% 16% 27% 18% 8% 4	452
	21st to end	Day	30% 13% 33% 15% 7% 2	460
May	1st to 10th	Day	25% 13% 29% 22% 8% 3	463
	11th to 20th	Day	22% 10% 29% 23% 11% 4	487
	21st to end	Day	15% 8% 26% 29% 16% 6%	529
June	1st to 10th	Day	16% 7% 31% 30% 13% 3	490
	11th to 20th	Day	15% 8% 23% 34% 16% 4	526
	21st to end	Day	15% 8% 32% 28% 14% 4	680
July	1st to 10th	Day	12% 5% 23% 30% 19% 11%	612
	11th to 20th	Day	15% 5% 22% 30% 20% 8%	484
	21st to end	Day	12% 5% 24% 30% 22% 7%	532
August	1st to 10th	Day	14% 5% 20% 28% 23% 10%	486
	11th to 20th	Day	15% 4 23% 27% 20% 10%	479
	21st to end	Day	13% 5% 21% 28% 23% 10%	532
September	1st to 10th	Day	17% 5% 21% 25% 20% 11%	450
	11th to 20th	Day	13% 5% 17% 28% 25% 13%	450
	21st to end	Day	21% 11% 25% 21% 13% 9%	450
October	1st to 10th	Day	15% 8% 27% 24% 19% 7%	450
	11th to 20th	Day	22% 16% 33% 20% 8% 1	450
	21st to end	Day	32% 16% 31% 17% 5%	464
November	1st to 10th	Day	21% 20% 33% 16% 10% 1	270
	11th to 20th	Day	30% 21% 28% 14% 5% 1	270
	21st to end	Day	29% 20% 35% 14% 1	187
December	1st to 10th	Day	26% 21% 36% 12% 4 2	180
	11th to 20th	Day	24% 26% 37% 10% 3	180
	21st to end	Day	29% 21% 34% 14% 2	258
January	1st to 10th	Night	29% 19% 31% 16% 4	760
	11th to 20th	Night	33% 17% 30% 16% 4 1	760
	21st to end	Night	30% 16% 30% 20% 3	836
February	1st to 10th	Night	30% 16% 30% 21% 3	760
	11th to 20th	Night	26% 17% 34% 20% 3	743
	21st to end	Night	28% 17% 34% 19% 2	628
March	1st to 10th	Night	24% 15% 32% 24% 5%	760
	11th to 20th	Night	23% 15% 32% 23% 6% 1	760
	21st to end	Night	26% 11% 28% 25% 9%	836
April	1st to 10th	Night	22% 14% 30% 27% 6%	760
	11th to 20th	Night	23% 10% 32% 24% 10% 1	578
	21st to end	Night	20% 9% 33% 29% 8% 1	570
May	1st to 10th	Night	23% 6% 27% 34% 9% 1	570
	11th to 20th	Night	21% 5% 24% 35% 13% 2	561
	21st to end	Night	11% 4 23% 38% 21% 2	617
June	1st to 10th	Night	11% 4 26% 42% 16% 1	404
	11th to 20th	Night	12% 5% 23% 43% 17% 1	380
	21st to end	Night	12% 4 23% 41% 19%	447
July	1st to 10th	Night	11% 2 15% 40% 29% 3	555
	11th to 20th	Night	11% 2 20% 38% 27% 3	552
	21st to end	Night	11% 2 15% 42% 28% 2	624
August	1st to 10th	Night	10% 2 14% 44% 26% 4	567
	11th to 20th	Night	13% 4 13% 38% 28% 4	564
	21st to end	Night	11% 3 16% 36% 30% 4	625
September	1st to 10th	Night	15% 6% 13% 34% 26% 5%	720
	11th to 20th	Night	13% 3 15% 33% 29% 5%	720
	21st to end	Night	17% 6% 23% 30% 19% 4	720
October	1st to 10th	Night	18% 7% 22% 32% 19% 2	720
	11th to 20th	Night	25% 13% 28% 25% 8% 1	720
	21st to end	Night	32% 12% 27% 24% 5%	792
November	1st to 10th	Night	23% 12% 29% 26% 10% 1	740
	11th to 20th	Night	30% 14% 30% 17% 7% 1	760
	21st to end	Night	32% 14% 30% 18% 6%	760
December	1st to 10th	Night	33% 13% 31% 17% 5%	760
	11th to 20th	Night	29% 17% 31% 19% 3	760
	21st to end	Night	32% 14% 33% 19% 2	836

Page generated at 2024-08-27 09:49:42. Version ac07

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