Sigoglin Hills Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Sigoglin Hills Observatory clear sky chart from 2005-11-06 to 2024-11-04.

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	14% 8% 3 7% 5% 4 5% 4 6% 7% 38%	101485
	Night	14% 8% 3 7% 5% 4 4 3 5% 7% 39%	97489
Transparency	Day	44% 3 10% 25% 16% 2	105200
	Night	43% 3 10% 24% 17% 3	101900
Seeing	Day	17% 6% 22% 25% 19% 10%	15087
	Night	18% 6% 23% 32% 18% 3	24750

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% 15% 6% 8% 5% 4 5% 4 6% 6% 27%	2836
	11th to 20th	Day	16% 12% 4 16% 5% 6% 3 3 3 5% 26%	2840
	21st to end	Day	27% 14% 8% 7% 4 3 4 3 3 5% 22%	3124
February	1st to 10th	Day	18% 12% 5% 10% 5% 4 3 3 5% 5% 30%	1836
	11th to 20th	Day	17% 11% 4 8% 5% 4 5% 3 4 5% 33%	1848
	21st to end	Day	19% 12% 3 8% 5% 5% 3 4 6% 6% 30%	1570
March	1st to 10th	Day	23% 14% 3 7% 3 4 3 3 4 5% 30%	3166
	11th to 20th	Day	14% 6% 2 5% 4 4 4 3 5% 8% 44%	3480
	21st to end	Day	15% 8% 3 7% 5% 5% 5% 4 6% 7% 37%	3815
April	1st to 10th	Day	14% 8% 3 6% 5% 4 4 4 5% 8% 38%	2223
	11th to 20th	Day	16% 8% 3 6% 4 4 4 4 5% 7% 40%	2292
	21st to end	Day	16% 7% 2 6% 5% 5% 5% 4 6% 7% 37%	2470
May	1st to 10th	Day	19% 9% 3 8% 5% 5% 5% 4 6% 7% 30%	4082
	11th to 20th	Day	18% 8% 3 8% 4 3 4 3 5% 7% 37%	4081
	21st to end	Day	10% 5% 2 7% 5% 5% 6% 5% 8% 10% 36%	4476
June	1st to 10th	Day	12% 4 2 7% 5% 5% 5% 4 6% 8% 42%	2470
	11th to 20th	Day	8% 5% 2 6% 5% 5% 5% 6% 7% 9% 43%	2504
	21st to end	Day	8% 5% 2 6% 5% 5% 5% 5% 8% 10% 41%	2660
July	1st to 10th	Day	11% 6% 2 7% 5% 5% 5% 4 7% 10% 39%	4377
	11th to 20th	Day	7% 5% 2 5% 4 5% 6% 5% 8% 10% 44%	4120
	21st to end	Day	13% 10% 3 10% 7% 7% 6% 4 7% 8% 25%	4466
August	1st to 10th	Day	7% 5% 2 6% 5% 4 5% 4 8% 10% 45%	4104
	11th to 20th	Day	7% 6% 2 6% 5% 5% 5% 5% 8% 11% 39%	4026
	21st to end	Day	5% 3 2 5% 3 4 5% 4 6% 9% 55%	4180
September	1st to 10th	Day	14% 5% 2 5% 5% 4 5% 4 6% 7% 43%	2151
	11th to 20th	Day	11% 5% 2 5% 5% 4 4 4 5% 7% 48%	2090
	21st to end	Day	14% 7% 2 6% 4 3 3 3 5% 7% 46%	2090
October	1st to 10th	Day	10% 5% 1 5% 4 4 4 3 5% 7% 53%	2090
	11th to 20th	Day	13% 6% 2 5% 3 4 4 3 5% 6% 49%	1938
	21st to end	Day	19% 6% 2 6% 4 3 3 3 6% 6% 43%	1974
November	1st to 10th	Day	12% 5% 2 5% 3 4 3 3 4 5% 55%	1699
	11th to 20th	Day	16% 10% 3 7% 4 4 3 3 5% 6% 42%	1710
	21st to end	Day	17% 9% 3 7% 4 3 4 3 5% 6% 38%	1710
December	1st to 10th	Day	21% 13% 4 8% 4 4 4 3 4 5% 29%	1710
	11th to 20th	Day	14% 13% 3 9% 6% 5% 5% 3 5% 5% 33%	2153
	21st to end	Day	18% 15% 5% 10% 6% 5% 5% 4 4 6% 22%	3124
January	1st to 10th	Night	14% 15% 5% 11% 6% 5% 4 4 5% 6% 26%	4109
	11th to 20th	Night	17% 13% 5% 13% 5% 4 4 2 4 4 28%	4120
	21st to end	Night	24% 14% 5% 8% 4 4 3 3 4 5% 27%	4532
February	1st to 10th	Night	21% 11% 5% 8% 4 5% 4 3 4 6% 30%	2342
	11th to 20th	Night	18% 10% 4 8% 5% 5% 4 3 4 6% 32%	2218
	21st to end	Night	20% 14% 4 8% 5% 4 4 3 4 4 30%	1884
March	1st to 10th	Night	20% 14% 3 7% 4 4 4 3 3 6% 33%	3684
	11th to 20th	Night	14% 6% 2 5% 4 3 4 3 4 6% 49%	3480
	21st to end	Night	14% 8% 2 6% 5% 4 4 4 6% 6% 39%	3817
April	1st to 10th	Night	12% 5% 2 6% 6% 5% 5% 4 7% 7% 41%	1971
	11th to 20th	Night	15% 7% 2 6% 4 4 4 3 5% 6% 43%	1835
	21st to end	Night	16% 7% 3 6% 4 5% 5% 3 6% 7% 40%	1710
May	1st to 10th	Night	18% 9% 3 9% 6% 5% 5% 4 7% 6% 27%	2813
	11th to 20th	Night	18% 7% 2 6% 4 4 4 4 6% 8% 37%	2812
	21st to end	Night	8% 5% 2 6% 4 5% 4 5% 7% 9% 44%	3079
June	1st to 10th	Night	8% 4 2 5% 4 5% 5% 4 6% 11% 46%	1710
	11th to 20th	Night	6% 4 2 6% 4 4 5% 5% 6% 10% 49%	1666
	21st to end	Night	7% 4 1 4 5% 5% 4 5% 8% 10% 46%	1520
July	1st to 10th	Night	7% 5% 2 7% 5% 5% 5% 4 5% 11% 44%	2582
	11th to 20th	Night	6% 4 2 5% 4 4 4 5% 7% 10% 49%	2840
	21st to end	Night	12% 10% 4 9% 4 5% 5% 4 6% 8% 33%	3087
August	1st to 10th	Night	6% 5% 2 6% 5% 4 4 4 6% 10% 47%	2825
	11th to 20th	Night	6% 5% 2 7% 5% 5% 5% 5% 7% 9% 44%	2799
	21st to end	Night	4 3 1 4 3 3 3 3 6% 9% 61%	3476
September	1st to 10th	Night	12% 5% 2 4 3 4 4 2 6% 9% 49%	2009
	11th to 20th	Night	10% 5% 2 4 4 4 4 2 5% 7% 53%	2090
	21st to end	Night	14% 6% 1 6% 3 3 4 3 5% 6% 50%	2090
October	1st to 10th	Night	9% 4 2 5% 3 3 3 4 4 7% 57%	2090
	11th to 20th	Night	13% 6% 2 6% 4 4 4 3 5% 6% 48%	2242
	21st to end	Night	17% 6% 2 7% 4 4 3 3 4 6% 45%	2621
November	1st to 10th	Night	12% 5% 2 5% 5% 3 4 3 4 5% 51%	2452
	11th to 20th	Night	15% 8% 3 7% 4 3 4 2 4 6% 43%	2470
	21st to end	Night	16% 10% 3 7% 5% 3 4 2 5% 6% 39%	2470
December	1st to 10th	Night	20% 12% 4 6% 4 4 4 4 5% 5% 32%	2470
	11th to 20th	Night	18% 9% 3 9% 5% 4 4 3 5% 7% 34%	3042
	21st to end	Night	17% 14% 5% 11% 6% 6% 6% 4 5% 6% 20%	4532

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	58% 2 11% 18% 11% 1	2837
	11th to 20th	Day	64% 1 7% 20% 7% 1	2840
	21st to end	Day	67% 1 5% 21% 4 1	3124
February	1st to 10th	Day	57% 2 8% 21% 10% 2	1836
	11th to 20th	Day	55% 2 7% 20% 12% 3	1858
	21st to end	Day	55% 2 8% 22% 10% 3	1570
March	1st to 10th	Day	58% 2 6% 19% 10% 4	3166
	11th to 20th	Day	40% 3 11% 27% 18% 1	3480
	21st to end	Day	47% 3 11% 27% 12% 1	3815
April	1st to 10th	Day	45% 3 11% 26% 13% 3	2223
	11th to 20th	Day	45% 2 8% 25% 16% 4	2292
	21st to end	Day	46% 3 12% 24% 12% 2	2470
May	1st to 10th	Day	53% 3 13% 21% 9% 1	4120
	11th to 20th	Day	48% 3 12% 24% 13% 1	4085
	21st to end	Day	41% 5% 14% 21% 18% 2	4489
June	1st to 10th	Day	40% 4 10% 27% 17% 1	2470
	11th to 20th	Day	35% 5% 15% 26% 18% 2	2504
	21st to end	Day	38% 5% 14% 23% 17% 3	2660
July	1st to 10th	Day	39% 5% 13% 23% 18% 1	4309
	11th to 20th	Day	32% 6% 14% 34% 14% 1	4051
	21st to end	Day	55% 6% 11% 16% 10% 2	4324
August	1st to 10th	Day	31% 6% 15% 35% 12% 1	4091
	11th to 20th	Day	35% 6% 13% 29% 15% 1	4065
	21st to end	Day	26% 4 13% 33% 20% 3	4179
September	1st to 10th	Day	40% 3 10% 20% 20% 5%	2151
	11th to 20th	Day	36% 4 9% 25% 23% 3	2090
	21st to end	Day	39% 2 7% 28% 21% 3	2090
October	1st to 10th	Day	22% 3 6% 28% 39% 3	3480
	11th to 20th	Day	25% 3 10% 29% 31% 2	3204
	21st to end	Day	31% 2 9% 29% 23% 6%	3224
November	1st to 10th	Day	34% 2 7% 28% 25% 4	1699
	11th to 20th	Day	44% 2 8% 23% 19% 4	1710
	21st to end	Day	48% 2 7% 23% 18% 2	1710
December	1st to 10th	Day	59% 2 9% 19% 10% 1	1710
	11th to 20th	Day	56% 2 8% 19% 15% 1	2150
	21st to end	Day	64% 3 8% 17% 7% 1	3124
January	1st to 10th	Night	60% 2 7% 18% 12% 1	4109
	11th to 20th	Night	62% 2 6% 19% 9% 2	4120
	21st to end	Night	62% 1 7% 20% 9% 1	4532
February	1st to 10th	Night	56% 2 9% 22% 9% 1	2342
	11th to 20th	Night	55% 3 6% 22% 13% 1	2219
	21st to end	Night	59% 2 9% 16% 11% 3	1884
March	1st to 10th	Night	55% 2 5% 23% 12% 2	3684
	11th to 20th	Night	38% 2 10% 30% 18% 3	3480
	21st to end	Night	45% 2 10% 26% 15% 1	3817
April	1st to 10th	Night	41% 4 11% 25% 17% 2	1971
	11th to 20th	Night	42% 2 9% 21% 20% 6%	1835
	21st to end	Night	45% 3 11% 25% 14% 3	1710
May	1st to 10th	Night	56% 4 10% 21% 7% 2	2840
	11th to 20th	Night	46% 4 13% 26% 10% 1	2813
	21st to end	Night	35% 4 13% 26% 18% 3	3087
June	1st to 10th	Night	32% 4 13% 29% 17% 5%	1710
	11th to 20th	Night	30% 6% 16% 25% 20% 4	1666
	21st to end	Night	31% 6% 17% 24% 17% 5%	1520
July	1st to 10th	Night	36% 7% 12% 24% 18% 3	2541
	11th to 20th	Night	28% 6% 14% 32% 17% 2	2786
	21st to end	Night	47% 6% 11% 21% 13% 1	2988
August	1st to 10th	Night	30% 6% 16% 33% 13% 1	2814
	11th to 20th	Night	34% 6% 12% 30% 17% 1	2826
	21st to end	Night	20% 5% 14% 34% 22% 4	3476
September	1st to 10th	Night	33% 4 14% 23% 20% 7%	2009
	11th to 20th	Night	32% 3 9% 27% 26% 3	2090
	21st to end	Night	37% 3 7% 25% 24% 3	2090
October	1st to 10th	Night	22% 3 7% 23% 42% 3	3480
	11th to 20th	Night	26% 2 7% 26% 34% 5%	3715
	21st to end	Night	31% 2 7% 22% 30% 8%	4308
November	1st to 10th	Night	36% 3 7% 25% 25% 4	2452
	11th to 20th	Night	43% 2 6% 21% 22% 5%	2470
	21st to end	Night	48% 1 8% 26% 15% 2	2470
December	1st to 10th	Night	54% 2 9% 22% 12% 1	2470
	11th to 20th	Night	51% 2 8% 24% 14% 2	3044
	21st to end	Night	66% 2 9% 16% 8%	4532

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% 11% 37% 21% 9% 1	270
	11th to 20th	Day	27% 18% 32% 20% 4	270
	21st to end	Day	23% 15% 41% 16% 4 1	297
February	1st to 10th	Day	23% 12% 40% 19% 6%	270
	11th to 20th	Day	26% 16% 34% 17% 5% 1	270
	21st to end	Day	30% 11% 40% 15% 4	225
March	1st to 10th	Day	24% 13% 34% 22% 6%	290
	11th to 20th	Day	20% 12% 37% 23% 7% 1	460
	21st to end	Day	23% 13% 34% 21% 8% 1	506
April	1st to 10th	Day	20% 12% 28% 23% 13% 2	460
	11th to 20th	Day	19% 11% 29% 24% 13% 5%	452
	21st to end	Day	21% 8% 29% 27% 12% 4	460
May	1st to 10th	Day	20% 6% 29% 25% 15% 6%	463
	11th to 20th	Day	19% 3 20% 29% 21% 9%	487
	21st to end	Day	13% 2 19% 26% 22% 17%	529
June	1st to 10th	Day	14% 2 15% 26% 27% 16%	490
	11th to 20th	Day	10% 2 15% 31% 28% 14%	524
	21st to end	Day	9% 3 16% 34% 24% 14%	680
July	1st to 10th	Day	17% 1 10% 23% 24% 25%	635
	11th to 20th	Day	9% 2 12% 26% 30% 21%	484
	21st to end	Day	13% 2 9% 26% 31% 20%	532
August	1st to 10th	Day	13% 1 9% 23% 29% 24%	486
	11th to 20th	Day	12% 1 8% 31% 31% 16%	479
	21st to end	Day	10% 1 8% 23% 35% 23%	539
September	1st to 10th	Day	16% 1 8% 26% 27% 21%	490
	11th to 20th	Day	13% 1 9% 23% 33% 21%	490
	21st to end	Day	17% 4 17% 22% 29% 10%	490
October	1st to 10th	Day	11% 2 16% 34% 26% 11%	490
	11th to 20th	Day	13% 8% 27% 29% 16% 6%	490
	21st to end	Day	21% 6% 28% 28% 13% 2	423
November	1st to 10th	Day	16% 4 29% 29% 17% 5%	279
	11th to 20th	Day	22% 9% 31% 26% 10% 3	270
	21st to end	Day	22% 8% 31% 28% 9% 2	270
December	1st to 10th	Day	24% 13% 28% 25% 9% 1	270
	11th to 20th	Day	17% 13% 37% 21% 11%	270
	21st to end	Day	24% 13% 36% 19% 8%	297
January	1st to 10th	Night	22% 12% 36% 24% 5%	760
	11th to 20th	Night	29% 12% 33% 22% 4	760
	21st to end	Night	25% 10% 34% 28% 4	836
February	1st to 10th	Night	28% 8% 33% 28% 3	760
	11th to 20th	Night	25% 10% 38% 25% 2	743
	21st to end	Night	28% 10% 37% 23% 2	628
March	1st to 10th	Night	22% 13% 30% 28% 6%	760
	11th to 20th	Night	23% 9% 32% 28% 7% 1	760
	21st to end	Night	20% 8% 31% 33% 9%	836
April	1st to 10th	Night	16% 8% 31% 36% 9%	641
	11th to 20th	Night	17% 7% 30% 32% 13% 1	563
	21st to end	Night	19% 4 31% 34% 11% 1	570
May	1st to 10th	Night	20% 3 25% 34% 15% 3	570
	11th to 20th	Night	17% 3 16% 40% 22% 2	561
	21st to end	Night	10% 2 14% 38% 31% 6%	617
June	1st to 10th	Night	10% 14% 44% 28% 3	570
	11th to 20th	Night	8% 1 11% 41% 34% 4	570
	21st to end	Night	8% 1 13% 45% 30% 4	570
July	1st to 10th	Night	13% 1 9% 31% 33% 13%	555
	11th to 20th	Night	8% 1 8% 38% 41% 4	552
	21st to end	Night	11% 1 8% 37% 37% 6%	624
August	1st to 10th	Night	9% 1 5% 36% 43% 6%	567
	11th to 20th	Night	8% 1 6% 37% 41% 7%	564
	21st to end	Night	8% 4 34% 45% 8%	627
September	1st to 10th	Night	13% 1 7% 33% 40% 6%	679
	11th to 20th	Night	13% 2 9% 31% 39% 7%	760
	21st to end	Night	16% 3 15% 33% 30% 3	760
October	1st to 10th	Night	10% 3 17% 36% 29% 6%	760
	11th to 20th	Night	16% 4 25% 36% 18% 2	760
	21st to end	Night	21% 6% 26% 31% 14% 1	836
November	1st to 10th	Night	15% 6% 23% 36% 19% 2	755
	11th to 20th	Night	18% 7% 32% 31% 11% 1	760
	21st to end	Night	22% 8% 26% 32% 11% 1	760
December	1st to 10th	Night	25% 8% 31% 30% 6%	760
	11th to 20th	Night	24% 6% 32% 30% 6% 1	760
	21st to end	Night	27% 13% 30% 26% 4	836

Page generated at 2024-11-01 22:47:46. Version ac07

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