Eye In The Sky YOGO Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Eye In The Sky YOGO Observatory clear sky chart from 2005-11-06 to 2024-12-02.

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	6% 7% 3 7% 5% 5% 5% 4 7% 8% 44%	105736
	Night	4 6% 2 6% 4 4 5% 4 6% 8% 48%	102594
Transparency	Day	36% 5% 14% 24% 16% 5%	105468
	Night	32% 5% 16% 26% 16% 4	102452
Seeing	Day	15% 20% 31% 23% 10% 2	15655
	Night	11% 21% 29% 27% 10% 1	25117

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% 3 11% 7% 5% 6% 4 9% 11% 38%	2219
	11th to 20th	Day	1 7% 3 9% 7% 8% 8% 5% 7% 7% 38%	2284
	21st to end	Day	1 5% 2 6% 4 4 5% 4 6% 10% 52%	3082
February	1st to 10th	Day	2 8% 5% 11% 6% 6% 6% 5% 8% 9% 35%	1710
	11th to 20th	Day	1 9% 6% 13% 6% 6% 5% 4 6% 9% 34%	1665
	21st to end	Day	1 9% 5% 10% 7% 5% 5% 5% 7% 10% 36%	1427
March	1st to 10th	Day	1 5% 3 9% 6% 6% 6% 5% 7% 10% 42%	3375
	11th to 20th	Day	2 7% 4 7% 5% 4 5% 4 7% 9% 46%	3490
	21st to end	Day	4 16% 7% 14% 7% 7% 6% 5% 6% 6% 22%	3825
April	1st to 10th	Day	6% 15% 4 7% 6% 5% 5% 6% 7% 8% 31%	2237
	11th to 20th	Day	8% 14% 5% 11% 6% 5% 5% 4 6% 7% 28%	2416
	21st to end	Day	12% 16% 4 8% 5% 5% 4 5% 5% 7% 29%	2470
May	1st to 10th	Day	16% 17% 5% 8% 5% 4 4 4 5% 5% 27%	4225
	11th to 20th	Day	9% 9% 3 7% 6% 5% 6% 5% 8% 9% 33%	4388
	21st to end	Day	16% 9% 2 7% 6% 5% 6% 5% 7% 8% 30%	4908
June	1st to 10th	Day	13% 8% 3 6% 5% 6% 6% 5% 7% 8% 33%	2850
	11th to 20th	Day	13% 7% 3 6% 5% 5% 5% 5% 7% 9% 34%	2850
	21st to end	Day	4 4 2 6% 5% 4 5% 5% 7% 9% 48%	2850
July	1st to 10th	Day	4 3 1 5% 5% 5% 6% 6% 8% 9% 47%	4740
	11th to 20th	Day	2 2 1 3 3 3 5% 4 6% 9% 61%	4740
	21st to end	Day	3 2 1 4 4 4 5% 4 6% 7% 61%	4788
August	1st to 10th	Day	6% 4 2 6% 5% 5% 6% 5% 7% 8% 46%	4092
	11th to 20th	Day	4 3 1 5% 4 5% 6% 5% 7% 9% 49%	4028
	21st to end	Day	5% 3 1 4 3 4 4 4 6% 7% 59%	4504
September	1st to 10th	Day	7% 5% 1 5% 3 4 3 3 4 7% 58%	2280
	11th to 20th	Day	9% 6% 2 4 4 5% 4 4 6% 8% 49%	2142
	21st to end	Day	10% 5% 2 5% 3 3 4 3 4 7% 55%	2088
October	1st to 10th	Day	7% 7% 2 4 3 3 2 2 4 6% 59%	3170
	11th to 20th	Day	5% 7% 2 5% 3 3 4 3 5% 6% 57%	3150
	21st to end	Day	3 9% 4 7% 4 3 4 3 7% 7% 49%	3296
November	1st to 10th	Day	4 10% 4 8% 4 5% 5% 4 7% 8% 41%	1592
	11th to 20th	Day	2 8% 4 8% 4 6% 5% 5% 8% 11% 40%	1600
	21st to end	Day	1 9% 3 7% 4 5% 6% 5% 8% 9% 44%	1600
December	1st to 10th	Day	1 8% 3 7% 6% 5% 6% 5% 9% 10% 41%	1528
	11th to 20th	Day	2 6% 4 7% 5% 6% 4 5% 7% 11% 45%	1685
	21st to end	Day	1 8% 3 7% 5% 5% 4 5% 7% 9% 48%	2442
January	1st to 10th	Night	1 5% 2 6% 5% 5% 4 5% 7% 10% 49%	4726
	11th to 20th	Night	1 5% 3 9% 8% 8% 7% 6% 8% 8% 39%	4705
	21st to end	Night	2 7% 3 6% 4 4 4 4 7% 9% 49%	4580
February	1st to 10th	Night	2 9% 4 11% 7% 6% 6% 5% 6% 9% 36%	2470
	11th to 20th	Night	1 8% 5% 8% 5% 5% 6% 6% 8% 10% 38%	2402
	21st to end	Night	1 8% 4 9% 7% 6% 5% 5% 9% 10% 37%	2026
March	1st to 10th	Night	1 6% 2 6% 5% 4 5% 5% 7% 11% 48%	3499
	11th to 20th	Night	1 5% 2 5% 4 4 5% 4 6% 9% 55%	3490
	21st to end	Night	4 12% 5% 14% 6% 6% 5% 5% 8% 9% 26%	3828
April	1st to 10th	Night	6% 11% 3 7% 5% 5% 6% 4 7% 9% 38%	1942
	11th to 20th	Night	6% 11% 4 10% 6% 5% 5% 5% 7% 8% 33%	1710
	21st to end	Night	11% 10% 2 7% 4 5% 5% 4 6% 7% 40%	1710
May	1st to 10th	Night	15% 14% 3 7% 4 4 4 3 5% 6% 36%	2742
	11th to 20th	Night	8% 8% 3 5% 4 4 4 4 6% 10% 44%	2517
	21st to end	Night	13% 7% 3 7% 4 4 4 3 7% 8% 42%	2672
June	1st to 10th	Night	12% 6% 2 5% 5% 5% 5% 4 6% 9% 41%	1330
	11th to 20th	Night	10% 6% 2 6% 5% 5% 4 4 8% 8% 42%	1330
	21st to end	Night	5% 3 2 4 3 3 4 5% 7% 9% 57%	1330
July	1st to 10th	Night	3 2 1 3 2 3 4 3 6% 9% 62%	2220
	11th to 20th	Night	2 1 1 2 2 2 3 3 5% 6% 72%	2220
	21st to end	Night	4 3 1 4 4 4 5% 4 6% 8% 57%	2768
August	1st to 10th	Night	5% 4 1 5% 4 4 5% 4 6% 9% 52%	2847
	11th to 20th	Night	5% 4 1 4 4 4 6% 6% 8% 10% 50%	2811
	21st to end	Night	5% 3 1 5% 3 4 4 4 6% 7% 56%	3163
September	1st to 10th	Night	8% 4 1 4 4 3 4 3 4 7% 56%	1900
	11th to 20th	Night	9% 5% 2 5% 3 4 4 3 7% 8% 51%	2036
	21st to end	Night	9% 5% 1 4 3 3 4 3 6% 7% 55%	2091
October	1st to 10th	Night	7% 5% 2 4 3 3 3 3 4 6% 62%	3800
	11th to 20th	Night	5% 6% 2 6% 4 3 4 3 5% 7% 55%	3778
	21st to end	Night	4 7% 2 5% 3 4 4 4 6% 7% 55%	4258
November	1st to 10th	Night	4 9% 3 7% 5% 4 4 5% 7% 9% 45%	2687
	11th to 20th	Night	3 7% 3 6% 4 4 5% 4 8% 8% 48%	2800
	21st to end	Night	1 8% 3 6% 5% 5% 5% 5% 6% 10% 46%	2800
December	1st to 10th	Night	1 5% 3 7% 6% 6% 5% 6% 7% 9% 45%	2687
	11th to 20th	Night	2 6% 3 7% 4 4 5% 4 6% 9% 51%	3505
	21st to end	Night	1 6% 3 6% 3 5% 5% 5% 6% 7% 52%	5214

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	38% 4 17% 28% 12%	2219
	11th to 20th	Day	44% 5% 17% 17% 12% 5%	2284
	21st to end	Day	28% 4 27% 28% 12% 1	3082
February	1st to 10th	Day	45% 7% 20% 17% 9% 1	1710
	11th to 20th	Day	47% 6% 16% 21% 8% 2	1674
	21st to end	Day	43% 5% 17% 19% 12% 3	1427
March	1st to 10th	Day	34% 6% 14% 24% 21% 1	3375
	11th to 20th	Day	35% 4 22% 29% 9% 1	3490
	21st to end	Day	63% 3 14% 15% 4	3825
April	1st to 10th	Day	50% 5% 16% 22% 7% 1	2237
	11th to 20th	Day	55% 5% 12% 20% 8%	2419
	21st to end	Day	54% 3 15% 19% 7% 1	2470
May	1st to 10th	Day	60% 3 10% 21% 6% 1	4225
	11th to 20th	Day	45% 5% 14% 22% 11% 3	4392
	21st to end	Day	50% 5% 14% 20% 10% 1	4908
June	1st to 10th	Day	48% 5% 18% 22% 6% 1	2850
	11th to 20th	Day	45% 5% 14% 20% 12% 5%	2850
	21st to end	Day	30% 5% 15% 28% 19% 2	2850
July	1st to 10th	Day	26% 8% 12% 28% 20% 6%	4666
	11th to 20th	Day	16% 6% 9% 20% 28% 21%	4659
	21st to end	Day	18% 6% 6% 20% 29% 20%	4636
August	1st to 10th	Day	30% 7% 10% 20% 22% 10%	4078
	11th to 20th	Day	26% 9% 10% 27% 24% 5%	4067
	21st to end	Day	22% 5% 9% 28% 28% 8%	4503
September	1st to 10th	Day	28% 3 8% 29% 23% 10%	2280
	11th to 20th	Day	33% 4 11% 30% 18% 4	2142
	21st to end	Day	30% 4 11% 30% 19% 5%	2088
October	1st to 10th	Day	29% 2 8% 31% 25% 5%	3170
	11th to 20th	Day	28% 4 16% 28% 21% 3	3150
	21st to end	Day	32% 5% 13% 25% 18% 7%	3296
November	1st to 10th	Day	40% 5% 14% 25% 11% 4	1592
	11th to 20th	Day	35% 7% 20% 25% 10% 3	1600
	21st to end	Day	32% 7% 19% 26% 12% 3	1600
December	1st to 10th	Day	35% 7% 20% 23% 12% 3	1528
	11th to 20th	Day	34% 5% 30% 22% 7% 2	1684
	21st to end	Day	34% 4 11% 26% 13% 12%	2442
January	1st to 10th	Night	29% 6% 18% 31% 14% 2	4726
	11th to 20th	Night	41% 6% 16% 18% 15% 5%	4705
	21st to end	Night	29% 5% 23% 28% 13% 2	4580
February	1st to 10th	Night	45% 7% 18% 20% 9% 2	2470
	11th to 20th	Night	38% 5% 22% 24% 9% 2	2403
	21st to end	Night	39% 5% 18% 21% 12% 4	2026
March	1st to 10th	Night	28% 6% 14% 22% 27% 2	3499
	11th to 20th	Night	25% 4 27% 31% 10% 1	3490
	21st to end	Night	54% 3 20% 18% 3 1	3828
April	1st to 10th	Night	42% 6% 17% 24% 10% 1	1942
	11th to 20th	Night	46% 5% 15% 23% 9% 1	1710
	21st to end	Night	43% 4 18% 26% 8% 1	1710
May	1st to 10th	Night	51% 2 12% 21% 12% 2	2742
	11th to 20th	Night	35% 4 15% 31% 14% 1	2518
	21st to end	Night	41% 3 16% 28% 12% 1	2672
June	1st to 10th	Night	39% 6% 25% 22% 6% 1	1330
	11th to 20th	Night	38% 5% 17% 23% 13% 4	1330
	21st to end	Night	23% 4 18% 34% 19% 2	1330
July	1st to 10th	Night	17% 5% 12% 35% 29% 3	2185
	11th to 20th	Night	13% 3 6% 26% 31% 22%	2178
	21st to end	Night	22% 4 7% 24% 29% 13%	2682
August	1st to 10th	Night	25% 6% 12% 26% 21% 9%	2838
	11th to 20th	Night	25% 6% 11% 31% 22% 4	2838
	21st to end	Night	24% 5% 10% 34% 23% 4	3163
September	1st to 10th	Night	29% 3 8% 27% 24% 10%	1900
	11th to 20th	Night	32% 3 14% 30% 17% 4	2036
	21st to end	Night	28% 3 13% 30% 22% 4	2091
October	1st to 10th	Night	25% 3 9% 34% 23% 6%	3800
	11th to 20th	Night	30% 4 17% 24% 21% 4	3778
	21st to end	Night	27% 5% 15% 25% 22% 7%	4258
November	1st to 10th	Night	33% 8% 17% 25% 13% 4	2687
	11th to 20th	Night	30% 6% 21% 28% 14% 2	2800
	21st to end	Night	31% 6% 20% 27% 11% 5%	2800
December	1st to 10th	Night	32% 8% 22% 24% 11% 4	2687
	11th to 20th	Night	30% 6% 26% 29% 8% 1	3506
	21st to end	Night	30% 5% 12% 28% 13% 12%	5214

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	18% 27% 26% 18% 9% 2	180
	11th to 20th	Day	11% 33% 32% 15% 5% 3	180
	21st to end	Day	9% 35% 41% 10% 3 1	279
February	1st to 10th	Day	13% 36% 35% 12% 3	270
	11th to 20th	Day	10% 37% 31% 18% 3 1	270
	21st to end	Day	15% 30% 33% 15% 5% 2	239
March	1st to 10th	Day	12% 34% 37% 13% 4 1	460
	11th to 20th	Day	12% 28% 34% 19% 6% 1	460
	21st to end	Day	19% 22% 33% 17% 7% 2	506
April	1st to 10th	Day	20% 26% 37% 14% 2 1	460
	11th to 20th	Day	17% 30% 34% 15% 4	452
	21st to end	Day	26% 13% 32% 20% 8% 1	460
May	1st to 10th	Day	21% 12% 29% 22% 13% 3	526
	11th to 20th	Day	22% 11% 25% 25% 13% 4	675
	21st to end	Day	24% 13% 21% 21% 17% 4	734
June	1st to 10th	Day	16% 14% 26% 25% 13% 6%	680
	11th to 20th	Day	20% 23% 29% 20% 7% 1	680
	21st to end	Day	9% 13% 29% 30% 16% 2	680
July	1st to 10th	Day	8% 9% 30% 31% 17% 4	671
	11th to 20th	Day	4 10% 32% 38% 14% 2	668
	21st to end	Day	5% 7% 33% 36% 17% 2	673
August	1st to 10th	Day	9% 10% 34% 34% 10% 2	487
	11th to 20th	Day	9% 6% 32% 32% 18% 3	477
	21st to end	Day	8% 12% 33% 29% 15% 4	539
September	1st to 10th	Day	10% 11% 37% 29% 11% 2	490
	11th to 20th	Day	16% 16% 34% 21% 11% 3	490
	21st to end	Day	18% 17% 31% 22% 11% 2	488
October	1st to 10th	Day	18% 17% 32% 16% 13% 4	300
	11th to 20th	Day	16% 24% 31% 17% 9% 3	300
	21st to end	Day	16% 34% 27% 14% 6% 2	330
November	1st to 10th	Day	21% 27% 30% 15% 6% 2	300
	11th to 20th	Day	15% 44% 26% 12% 3	300
	21st to end	Day	14% 34% 28% 18% 5% 1	300
December	1st to 10th	Day	17% 41% 20% 14% 7% 1	273
	11th to 20th	Day	17% 35% 26% 17% 4 1	180
	21st to end	Day	16% 29% 31% 16% 7% 2	198
January	1st to 10th	Night	11% 35% 30% 17% 6% 1	950
	11th to 20th	Night	9% 35% 34% 14% 6% 1	928
	21st to end	Night	9% 33% 34% 16% 7%	836
February	1st to 10th	Night	8% 33% 29% 20% 8% 2	760
	11th to 20th	Night	7% 31% 33% 22% 6% 1	744
	21st to end	Night	9% 24% 33% 22% 10% 1	628
March	1st to 10th	Night	7% 25% 37% 22% 9% 1	760
	11th to 20th	Night	7% 24% 32% 27% 8% 1	760
	21st to end	Night	11% 16% 34% 28% 9% 1	836
April	1st to 10th	Night	13% 16% 34% 29% 8% 1	612
	11th to 20th	Night	12% 18% 32% 31% 7% 1	563
	21st to end	Night	18% 10% 28% 32% 11% 2	570
May	1st to 10th	Night	17% 13% 19% 33% 16% 1	570
	11th to 20th	Night	19% 7% 21% 36% 15% 2	561
	21st to end	Night	21% 9% 18% 33% 17% 2	566
June	1st to 10th	Night	16% 9% 16% 34% 21% 3	380
	11th to 20th	Night	15% 14% 29% 29% 11% 1	380
	21st to end	Night	6% 7% 20% 51% 15% 1	380
July	1st to 10th	Night	6% 3 21% 46% 24% 1	370
	11th to 20th	Night	5% 4 24% 52% 14% 1	368
	21st to end	Night	6% 3 25% 48% 18% 1	558
August	1st to 10th	Night	6% 2 23% 46% 21% 2	567
	11th to 20th	Night	7% 4 20% 45% 22% 3	564
	21st to end	Night	8% 7% 23% 39% 21% 2	627
September	1st to 10th	Night	10% 4 23% 44% 17% 2	570
	11th to 20th	Night	11% 6% 26% 38% 16% 3	706
	21st to end	Night	12% 11% 29% 31% 13% 4	760
October	1st to 10th	Night	15% 13% 25% 31% 14% 2	760
	11th to 20th	Night	12% 21% 29% 26% 10% 2	760
	21st to end	Night	11% 27% 31% 21% 8% 1	836
November	1st to 10th	Night	13% 29% 33% 19% 5% 1	932
	11th to 20th	Night	13% 35% 33% 15% 3	1000
	21st to end	Night	8% 31% 35% 21% 4 1	1000
December	1st to 10th	Night	11% 31% 30% 20% 7% 1	960
	11th to 20th	Night	10% 35% 32% 17% 6% 1	950
	21st to end	Night	11% 34% 29% 18% 7% 1	1045

Page generated at 2024-11-29 08:43:03. Version ac07

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