Ocean View Sky Shed
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Ocean View Sky Shed clear sky chart from 2005-11-06 to 2025-12-18.

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	12% 6% 2 6% 4 4 5% 4 6% 8% 42%	126714
	Night	13% 7% 2 6% 4 4 4 3 5% 7% 43%	124307
Transparency	Day	24% 39% 9% 15% 11% 2	130305
	Night	25% 38% 7% 15% 12% 3	128785
Seeing	Day	15% 8% 25% 27% 19% 6%	16713
	Night	16% 8% 26% 31% 16% 2	26311

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	14% 5% 1 4 3 3 4 3 3 5% 56%	3799
	11th to 20th	Day	11% 6% 2 6% 3 3 3 3 4 5% 53%	4060
	21st to end	Day	10% 8% 3 8% 5% 5% 4 4 5% 6% 44%	4466
February	1st to 10th	Day	13% 8% 3 6% 4 4 5% 4 6% 7% 40%	1800
	11th to 20th	Day	20% 7% 2 4 3 3 4 3 5% 5% 43%	1918
	21st to end	Day	16% 8% 2 6% 4 3 4 4 6% 8% 40%	1650
March	1st to 10th	Day	18% 8% 3 6% 4 3 4 3 5% 6% 41%	4745
	11th to 20th	Day	10% 7% 3 5% 3 4 4 3 4 6% 51%	4980
	21st to end	Day	13% 7% 2 5% 3 4 4 4 5% 7% 47%	5645
April	1st to 10th	Day	12% 6% 2 6% 4 3 4 3 5% 7% 49%	2400
	11th to 20th	Day	10% 5% 2 5% 4 4 5% 4 6% 6% 49%	2374
	21st to end	Day	12% 6% 2 6% 5% 4 4 3 6% 7% 45%	2400
May	1st to 10th	Day	13% 7% 2 8% 5% 5% 5% 5% 7% 10% 34%	5405
	11th to 20th	Day	17% 8% 3 7% 5% 5% 4 4 6% 8% 32%	6055
	21st to end	Day	13% 6% 2 6% 4 4 4 3 6% 9% 42%	6934
June	1st to 10th	Day	9% 5% 2 5% 3 4 5% 5% 8% 11% 42%	2800
	11th to 20th	Day	10% 6% 2 5% 4 5% 5% 4 7% 11% 42%	2800
	21st to end	Day	6% 4 2 5% 5% 5% 6% 5% 8% 12% 42%	2800
July	1st to 10th	Day	7% 5% 2 6% 4 5% 6% 6% 9% 13% 38%	6360
	11th to 20th	Day	10% 6% 3 8% 6% 6% 6% 6% 8% 12% 30%	6048
	21st to end	Day	6% 4 2 7% 6% 6% 6% 6% 8% 11% 37%	6424
August	1st to 10th	Day	14% 8% 4 9% 5% 6% 6% 5% 8% 10% 25%	4182
	11th to 20th	Day	9% 6% 2 7% 5% 6% 6% 5% 7% 10% 37%	3850
	21st to end	Day	8% 4 2 5% 4 5% 5% 5% 7% 11% 44%	4312
September	1st to 10th	Day	14% 5% 2 6% 4 4 5% 5% 7% 9% 41%	2400
	11th to 20th	Day	14% 8% 2 7% 4 4 4 4 6% 7% 41%	2400
	21st to end	Day	20% 8% 2 6% 4 4 4 3 5% 8% 36%	2146
October	1st to 10th	Day	17% 5% 3 5% 3 4 3 3 5% 6% 46%	2000
	11th to 20th	Day	15% 5% 2 6% 3 3 4 3 4 5% 51%	2000
	21st to end	Day	12% 5% 2 5% 5% 3 4 3 4 6% 51%	2200
November	1st to 10th	Day	15% 6% 1 5% 3 3 3 4 4 7% 49%	1947
	11th to 20th	Day	13% 7% 2 4 5% 3 4 3 4 8% 48%	1890
	21st to end	Day	13% 4 2 5% 4 3 5% 3 5% 5% 51%	1838
December	1st to 10th	Day	12% 5% 2 5% 4 3 4 3 5% 5% 52%	2680
	11th to 20th	Day	15% 8% 3 6% 4 3 4 3 5% 5% 44%	3046
	21st to end	Day	12% 5% 2 5% 3 3 3 3 5% 8% 49%	3960
January	1st to 10th	Night	12% 7% 3 5% 3 3 3 3 4 5% 52%	6142
	11th to 20th	Night	13% 7% 2 5% 4 3 3 3 4 5% 52%	5900
	21st to end	Night	14% 7% 2 6% 4 3 3 2 5% 6% 47%	6490
February	1st to 10th	Night	16% 7% 3 6% 4 4 4 3 5% 6% 42%	2600
	11th to 20th	Night	21% 7% 2 5% 4 3 4 3 4 7% 40%	2366
	21st to end	Night	15% 8% 2 5% 4 3 3 3 4 6% 47%	1980
March	1st to 10th	Night	17% 8% 2 7% 4 4 4 3 4 5% 42%	5103
	11th to 20th	Night	12% 6% 3 5% 4 4 4 3 4 5% 48%	4980
	21st to end	Night	15% 8% 3 5% 3 4 4 3 4 5% 46%	5285
April	1st to 10th	Night	13% 7% 2 5% 5% 4 5% 4 6% 7% 43%	2000
	11th to 20th	Night	12% 6% 2 5% 4 3 3 3 5% 7% 50%	1975
	21st to end	Night	14% 6% 2 4 3 5% 5% 3 5% 7% 46%	2000
May	1st to 10th	Night	12% 9% 3 8% 5% 5% 6% 4 6% 9% 32%	4490
	11th to 20th	Night	20% 8% 3 7% 5% 5% 4 3 5% 8% 31%	3863
	21st to end	Night	14% 8% 3 7% 5% 5% 4 4 5% 8% 36%	3920
June	1st to 10th	Night	11% 6% 2 5% 5% 5% 4 5% 7% 11% 39%	1600
	11th to 20th	Night	8% 6% 3 7% 5% 5% 5% 5% 7% 10% 41%	1600
	21st to end	Night	6% 6% 2 6% 4 6% 5% 5% 7% 10% 44%	1600
July	1st to 10th	Night	7% 5% 2 6% 5% 5% 7% 5% 9% 13% 36%	3598
	11th to 20th	Night	9% 7% 3 8% 5% 5% 6% 6% 8% 12% 32%	3890
	21st to end	Night	10% 7% 3 8% 5% 6% 5% 4 7% 10% 35%	4427
August	1st to 10th	Night	15% 9% 3 8% 5% 5% 5% 4 7% 10% 29%	2933
	11th to 20th	Night	9% 7% 3 8% 5% 5% 5% 4 6% 9% 40%	3197
	21st to end	Night	9% 5% 2 6% 4 4 5% 4 8% 9% 44%	3586
September	1st to 10th	Night	11% 6% 1 6% 5% 3 5% 4 5% 9% 45%	2000
	11th to 20th	Night	14% 7% 2 6% 5% 4 4 3 4 7% 43%	2000
	21st to end	Night	19% 8% 3 6% 5% 5% 4 3 6% 7% 35%	2248
October	1st to 10th	Night	14% 6% 2 5% 4 4 4 3 5% 6% 47%	2400
	11th to 20th	Night	17% 6% 2 5% 3 3 3 3 4 6% 49%	2400
	21st to end	Night	14% 5% 2 5% 3 4 3 3 4 6% 50%	2640
November	1st to 10th	Night	15% 6% 2 6% 3 3 3 3 5% 6% 48%	2567
	11th to 20th	Night	15% 6% 3 6% 3 3 4 4 5% 6% 46%	2730
	21st to end	Night	11% 5% 1 5% 4 4 4 3 5% 7% 50%	2777
December	1st to 10th	Night	10% 5% 2 6% 4 4 4 3 4 5% 53%	4720
	11th to 20th	Night	16% 8% 3 7% 5% 5% 4 3 5% 5% 39%	5304
	21st to end	Night	11% 6% 2 6% 4 4 4 4 5% 7% 48%	6996

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	24% 26% 2 20% 18% 11%	3800
	11th to 20th	Day	24% 26% 3 14% 27% 5%	4060
	21st to end	Day	32% 29% 6% 21% 11% 2	4466
February	1st to 10th	Day	17% 62% 5% 11% 5% 1	1800
	11th to 20th	Day	19% 61% 4 7% 6% 3	1927
	21st to end	Day	15% 62% 5% 8% 7% 2	1650
March	1st to 10th	Day	37% 28% 5% 11% 13% 6%	4745
	11th to 20th	Day	24% 28% 5% 14% 21% 8%	4980
	21st to end	Day	26% 30% 10% 14% 16% 5%	5645
April	1st to 10th	Day	16% 62% 5% 8% 9% 1	2400
	11th to 20th	Day	13% 63% 5% 10% 8% 1	2374
	21st to end	Day	14% 63% 6% 9% 6% 2	2400
May	1st to 10th	Day	34% 31% 14% 13% 6% 1	5437
	11th to 20th	Day	37% 30% 11% 16% 6%	6059
	21st to end	Day	28% 30% 10% 20% 10% 2	6949
June	1st to 10th	Day	14% 63% 6% 10% 6% 1	2800
	11th to 20th	Day	11% 64% 7% 10% 7%	2800
	21st to end	Day	11% 62% 7% 13% 7%	2800
July	1st to 10th	Day	25% 32% 18% 17% 8% 1	6290
	11th to 20th	Day	34% 33% 20% 11% 1	5975
	21st to end	Day	28% 30% 11% 20% 11%	6240
August	1st to 10th	Day	37% 39% 12% 11% 1	4169
	11th to 20th	Day	23% 41% 11% 16% 8%	3886
	21st to end	Day	18% 38% 10% 21% 13% 1	4312
September	1st to 10th	Day	17% 59% 8% 10% 5% 2	2400
	11th to 20th	Day	19% 58% 5% 9% 7% 2	2400
	21st to end	Day	24% 58% 5% 9% 3	2146
October	1st to 10th	Day	17% 37% 8% 20% 17% 2	3260
	11th to 20th	Day	13% 36% 4 12% 29% 6%	3240
	21st to end	Day	9% 36% 7% 20% 19% 9%	3538
November	1st to 10th	Day	19% 54% 5% 13% 8% 1	1947
	11th to 20th	Day	18% 54% 5% 10% 11% 3	1890
	21st to end	Day	16% 55% 4 13% 11% 1	1838
December	1st to 10th	Day	22% 35% 5% 21% 15% 2	2680
	11th to 20th	Day	30% 31% 10% 13% 12% 3	3042
	21st to end	Day	25% 27% 11% 24% 12%	3960
January	1st to 10th	Night	26% 26% 2 16% 22% 7%	6142
	11th to 20th	Night	26% 25% 2 17% 25% 4	5900
	21st to end	Night	28% 29% 5% 21% 14% 3	6490
February	1st to 10th	Night	16% 62% 6% 9% 6%	2600
	11th to 20th	Night	21% 61% 3 8% 7% 1	2368
	21st to end	Night	15% 61% 3 10% 7% 4	1980
March	1st to 10th	Night	35% 29% 5% 13% 12% 6%	5103
	11th to 20th	Night	26% 29% 5% 12% 18% 8%	4980
	21st to end	Night	29% 30% 6% 18% 12% 5%	5285
April	1st to 10th	Night	17% 63% 4 6% 9% 1	2000
	11th to 20th	Night	14% 63% 5% 10% 7% 1	1975
	21st to end	Night	16% 62% 5% 9% 7% 1	2000
May	1st to 10th	Night	35% 32% 13% 12% 6%	4520
	11th to 20th	Night	40% 30% 8% 17% 4	3864
	21st to end	Night	36% 30% 9% 17% 8%	3927
June	1st to 10th	Night	16% 64% 5% 7% 6% 1	1600
	11th to 20th	Night	13% 64% 7% 9% 7%	1600
	21st to end	Night	13% 62% 5% 13% 7% 1	1600
July	1st to 10th	Night	28% 33% 14% 16% 7% 1	3560
	11th to 20th	Night	34% 34% 19% 12% 1	3843
	21st to end	Night	34% 29% 8% 17% 12%	4297
August	1st to 10th	Night	36% 38% 12% 12% 2	2922
	11th to 20th	Night	26% 39% 10% 17% 8%	3227
	21st to end	Night	19% 38% 6% 19% 17% 1	3586
September	1st to 10th	Night	17% 58% 9% 11% 4 1	2000
	11th to 20th	Night	20% 58% 4 9% 8% 2	2000
	21st to end	Night	26% 58% 5% 8% 3	2248
October	1st to 10th	Night	23% 37% 6% 17% 16% 1	3920
	11th to 20th	Night	15% 36% 3 12% 26% 8%	3899
	21st to end	Night	10% 35% 4 23% 20% 9%	4252
November	1st to 10th	Night	20% 53% 5% 11% 9% 1	2567
	11th to 20th	Night	19% 54% 4 10% 9% 5%	2730
	21st to end	Night	15% 55% 5% 13% 11% 1	2777
December	1st to 10th	Night	21% 35% 4 19% 18% 2	4720
	11th to 20th	Night	35% 32% 7% 12% 10% 4	5307
	21st to end	Night	27% 28% 11% 22% 11% 1	6996

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	19% 17% 43% 16% 5%	243
	11th to 20th	Day	20% 19% 38% 21% 2	300
	21st to end	Day	17% 14% 40% 24% 4 1	330
February	1st to 10th	Day	18% 14% 43% 19% 6%	300
	11th to 20th	Day	27% 18% 37% 15% 2	466
	21st to end	Day	20% 15% 39% 22% 4	414
March	1st to 10th	Day	15% 18% 39% 22% 6%	500
	11th to 20th	Day	19% 17% 35% 22% 6% 1	500
	21st to end	Day	14% 15% 38% 27% 5%	550
April	1st to 10th	Day	15% 16% 38% 22% 8% 1	500
	11th to 20th	Day	11% 12% 33% 29% 12% 2	492
	21st to end	Day	13% 11% 32% 30% 12% 2	500
May	1st to 10th	Day	16% 10% 32% 28% 13% 1	503
	11th to 20th	Day	18% 7% 25% 32% 17% 2	527
	21st to end	Day	18% 3 21% 30% 21% 6%	573
June	1st to 10th	Day	12% 3 18% 34% 27% 6%	530
	11th to 20th	Day	12% 5% 18% 27% 27% 11%	530
	21st to end	Day	8% 3 14% 36% 31% 8%	530
July	1st to 10th	Day	9% 1 9% 31% 38% 12%	525
	11th to 20th	Day	9% 2 7% 28% 40% 14%	524
	21st to end	Day	7% 2 13% 30% 34% 13%	576
August	1st to 10th	Day	14% 2 12% 32% 31% 9%	526
	11th to 20th	Day	12% 3 10% 31% 33% 13%	519
	21st to end	Day	11% 2 12% 30% 33% 12%	583
September	1st to 10th	Day	16% 2 14% 28% 26% 13%	530
	11th to 20th	Day	16% 3 17% 28% 25% 11%	530
	21st to end	Day	22% 7% 19% 27% 21% 4	530
October	1st to 10th	Day	20% 4 18% 25% 24% 10%	530
	11th to 20th	Day	16% 8% 24% 28% 20% 4	530
	21st to end	Day	15% 7% 31% 27% 14% 5%	583
November	1st to 10th	Day	17% 8% 25% 29% 17% 4	477
	11th to 20th	Day	16% 14% 31% 25% 12% 2	430
	21st to end	Day	16% 13% 27% 27% 15% 2	378
December	1st to 10th	Day	22% 9% 40% 21% 7% 1	220
	11th to 20th	Day	18% 13% 33% 28% 9%	214
	21st to end	Day	20% 13% 31% 23% 13%	220
January	1st to 10th	Night	16% 18% 36% 24% 6%	800
	11th to 20th	Night	20% 16% 32% 26% 7%	800
	21st to end	Night	20% 13% 37% 28% 2	880
February	1st to 10th	Night	20% 10% 40% 26% 4	800
	11th to 20th	Night	24% 17% 39% 18% 3	783
	21st to end	Night	19% 15% 35% 27% 4	660
March	1st to 10th	Night	17% 11% 37% 29% 7%	800
	11th to 20th	Night	20% 12% 37% 25% 6% 1	800
	21st to end	Night	19% 11% 36% 28% 5%	880
April	1st to 10th	Night	18% 13% 38% 26% 6%	800
	11th to 20th	Night	13% 10% 34% 32% 10% 1	791
	21st to end	Night	14% 8% 30% 37% 10% 1	800
May	1st to 10th	Night	15% 9% 33% 33% 9% 1	800
	11th to 20th	Night	16% 4 25% 39% 15% 1	526
	21st to end	Night	15% 3 17% 37% 24% 4	433
June	1st to 10th	Night	12% 3 17% 42% 22% 4	400
	11th to 20th	Night	11% 2 17% 40% 28% 4	400
	21st to end	Night	8% 2 13% 43% 32% 3	400
July	1st to 10th	Night	6% 1 12% 41% 36% 4	390
	11th to 20th	Night	8% 1 5% 38% 42% 5%	510
	21st to end	Night	9% 3 11% 40% 32% 5%	657
August	1st to 10th	Night	11% 2 10% 41% 32% 5%	602
	11th to 20th	Night	13% 2 11% 35% 34% 6%	790
	21st to end	Night	12% 2 11% 30% 37% 8%	880
September	1st to 10th	Night	15% 2 11% 36% 28% 7%	800
	11th to 20th	Night	16% 2 12% 33% 30% 6%	800
	21st to end	Night	22% 5% 15% 32% 23% 3	800
October	1st to 10th	Night	18% 4 16% 29% 27% 7%	800
	11th to 20th	Night	19% 8% 24% 30% 18% 2	800
	21st to end	Night	15% 8% 27% 28% 18% 4	880
November	1st to 10th	Night	18% 7% 24% 30% 17% 3	820
	11th to 20th	Night	16% 11% 31% 29% 12% 1	840
	21st to end	Night	14% 11% 30% 31% 13% 1	840
December	1st to 10th	Night	20% 13% 32% 26% 8% 1	840
	11th to 20th	Night	19% 10% 35% 29% 7%	829
	21st to end	Night	17% 11% 30% 33% 8%	880

Page generated at 2025-12-15 01:13:53. Version ac07

Copyright © 2025 Attilla Danko.