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 2024-04-10.

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	15% 8% 3 6% 6% 3 5% 5% 5% 7% 37%	83778
	Night	14% 8% 3 6% 5% 3 4 4 5% 7% 39%	84996
Transparency	Day	47% 3 10% 23% 14% 2	83498
	Night	46% 3 10% 23% 16% 3	84796
Seeing	Day	17% 6% 22% 25% 19% 10%	14246
	Night	18% 6% 23% 32% 18% 3	24066

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	15% 14% 6% 7% 6% 3 5% 5% 6% 6% 27%	2836
	11th to 20th	Day	16% 12% 5% 15% 6% 5% 4 4 3 5% 26%	2840
	21st to end	Day	27% 13% 9% 7% 5% 2 4 3 3 5% 22%	3124
February	1st to 10th	Day	18% 11% 5% 9% 6% 3 4 3 5% 6% 30%	1836
	11th to 20th	Day	17% 10% 4 8% 6% 3 5% 5% 4 5% 33%	1848
	21st to end	Day	19% 11% 3 7% 5% 4 4 5% 6% 6% 30%	1570
March	1st to 10th	Day	23% 13% 3 6% 4 3 3 4 4 6% 30%	3166
	11th to 20th	Day	14% 5% 3 4 5% 3 4 4 5% 8% 44%	3480
	21st to end	Day	15% 7% 3 6% 6% 4 5% 5% 6% 7% 38%	3815
April	1st to 10th	Day	14% 8% 3 5% 6% 3 4 5% 5% 8% 38%	2212
	11th to 20th	Day	16% 8% 3 5% 4 3 4 5% 5% 7% 39%	2169
	21st to end	Day	17% 7% 3 5% 6% 3 5% 5% 6% 7% 36%	2340
May	1st to 10th	Day	19% 6% 3 5% 5% 4 5% 5% 6% 7% 35%	2340
	11th to 20th	Day	17% 7% 4 7% 6% 3 4 5% 6% 7% 35%	2301
	21st to end	Day	8% 5% 3 5% 7% 4 7% 7% 7% 9% 38%	2531
June	1st to 10th	Day	12% 4 3 6% 6% 3 5% 5% 6% 8% 43%	2340
	11th to 20th	Day	8% 4 2 5% 5% 4 6% 7% 7% 9% 43%	2372
	21st to end	Day	9% 4 3 5% 5% 4 6% 6% 7% 10% 40%	2520
July	1st to 10th	Day	13% 6% 2 6% 5% 3 6% 7% 7% 9% 36%	2485
	11th to 20th	Day	9% 5% 2 6% 6% 4 7% 7% 7% 10% 38%	2340
	21st to end	Day	11% 5% 2 5% 6% 4 6% 5% 7% 9% 39%	2547
August	1st to 10th	Day	10% 5% 2 4 5% 3 5% 5% 8% 10% 41%	2327
	11th to 20th	Day	8% 6% 3 6% 7% 4 5% 6% 8% 10% 37%	2299
	21st to end	Day	8% 4 2 5% 6% 3 5% 6% 6% 9% 44%	2376
September	1st to 10th	Day	15% 5% 2 4 6% 3 5% 5% 6% 7% 42%	2038
	11th to 20th	Day	11% 4 2 4 5% 4 4 5% 6% 7% 48%	1980
	21st to end	Day	13% 6% 2 5% 5% 3 3 3 4 7% 49%	1980
October	1st to 10th	Day	10% 5% 1 4 5% 3 4 4 5% 7% 51%	1980
	11th to 20th	Day	14% 6% 2 4 4 3 4 4 5% 6% 48%	1836
	21st to end	Day	20% 6% 2 5% 5% 2 3 3 6% 5% 42%	1871
November	1st to 10th	Day	12% 4 3 4 4 3 4 4 3 5% 55%	1672
	11th to 20th	Day	16% 9% 3 6% 4 3 3 4 5% 6% 42%	1710
	21st to end	Day	18% 8% 3 6% 5% 3 3 4 5% 6% 39%	1710
December	1st to 10th	Day	21% 12% 4 8% 5% 3 4 5% 4 5% 29%	1710
	11th to 20th	Day	14% 13% 3 8% 7% 3 5% 5% 4 5% 33%	2153
	21st to end	Day	18% 15% 5% 8% 7% 4 5% 5% 4 6% 22%	3124
January	1st to 10th	Night	15% 14% 5% 9% 7% 4 4 5% 5% 6% 26%	4109
	11th to 20th	Night	18% 13% 5% 11% 7% 3 4 3 4 4 28%	4120
	21st to end	Night	24% 13% 5% 7% 5% 3 4 3 4 5% 27%	4532
February	1st to 10th	Night	21% 10% 5% 7% 5% 4 4 4 4 6% 30%	2342
	11th to 20th	Night	18% 9% 4 8% 6% 3 5% 4 4 6% 32%	2218
	21st to end	Night	21% 13% 4 6% 6% 3 4 4 4 4 30%	1884
March	1st to 10th	Night	20% 13% 3 6% 5% 3 4 4 3 6% 33%	3684
	11th to 20th	Night	14% 6% 2 4 4 2 4 4 4 6% 49%	3480
	21st to end	Night	14% 7% 3 5% 6% 3 5% 4 6% 6% 40%	3817
April	1st to 10th	Night	13% 5% 3 5% 6% 4 5% 5% 7% 7% 41%	1971
	11th to 20th	Night	15% 7% 3 6% 4 3 4 4 5% 6% 44%	1738
	21st to end	Night	16% 7% 3 5% 5% 3 6% 4 5% 6% 40%	1620
May	1st to 10th	Night	16% 6% 3 6% 7% 4 6% 5% 7% 6% 34%	1620
	11th to 20th	Night	14% 6% 3 6% 6% 4 6% 6% 6% 8% 35%	1592
	21st to end	Night	7% 4 2 5% 5% 4 6% 7% 8% 10% 41%	1744
June	1st to 10th	Night	8% 3 3 4 4 3 5% 5% 6% 11% 47%	1620
	11th to 20th	Night	6% 3 2 5% 5% 2 5% 7% 6% 10% 49%	1579
	21st to end	Night	7% 4 2 4 5% 4 5% 5% 7% 10% 47%	1440
July	1st to 10th	Night	9% 6% 2 6% 5% 4 5% 5% 6% 9% 42%	1466
	11th to 20th	Night	5% 3 2 5% 5% 3 4 6% 7% 11% 48%	1620
	21st to end	Night	8% 5% 3 4 4 4 6% 5% 6% 8% 48%	1771
August	1st to 10th	Night	7% 4 2 5% 5% 2 4 5% 6% 11% 48%	1611
	11th to 20th	Night	7% 4 2 5% 5% 3 5% 7% 7% 10% 45%	1598
	21st to end	Night	6% 4 2 4 5% 2 4 4 6% 9% 55%	1980
September	1st to 10th	Night	12% 4 2 4 3 3 4 3 6% 9% 49%	1903
	11th to 20th	Night	10% 5% 2 4 5% 3 4 3 4 7% 53%	1980
	21st to end	Night	13% 5% 2 5% 4 2 4 4 4 6% 52%	1980
October	1st to 10th	Night	9% 4 2 4 4 2 3 5% 4 7% 56%	1980
	11th to 20th	Night	13% 6% 2 5% 5% 3 4 5% 5% 7% 46%	2124
	21st to end	Night	18% 6% 2 6% 5% 3 3 4 4 6% 43%	2483
November	1st to 10th	Night	12% 5% 2 4 6% 2 4 4 4 5% 52%	2406
	11th to 20th	Night	15% 7% 3 6% 5% 2 4 4 4 6% 44%	2470
	21st to end	Night	16% 9% 4 6% 5% 2 4 3 5% 6% 39%	2470
December	1st to 10th	Night	20% 11% 4 6% 4 3 4 4 5% 5% 32%	2470
	11th to 20th	Night	18% 9% 4 8% 5% 2 4 4 5% 7% 34%	3042
	21st to end	Night	17% 14% 5% 9% 8% 4 5% 6% 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	2212
	11th to 20th	Day	45% 3 8% 24% 16% 4	2169
	21st to end	Day	47% 4 11% 24% 12% 2	2340
May	1st to 10th	Day	48% 4 12% 23% 11% 1	2340
	11th to 20th	Day	49% 3 13% 21% 12% 1	2305
	21st to end	Day	40% 6% 17% 23% 13% 1	2531
June	1st to 10th	Day	40% 3 10% 28% 17% 1	2340
	11th to 20th	Day	36% 5% 15% 25% 17% 2	2372
	21st to end	Day	38% 5% 14% 23% 17% 3	2520
July	1st to 10th	Day	43% 5% 13% 20% 17% 2	2417
	11th to 20th	Day	40% 5% 14% 24% 15% 2	2271
	21st to end	Day	41% 4 14% 26% 13% 3	2405
August	1st to 10th	Day	37% 5% 15% 28% 14% 1	2314
	11th to 20th	Day	41% 4 13% 26% 15% 1	2299
	21st to end	Day	36% 4 13% 26% 17% 5%	2376
September	1st to 10th	Day	42% 3 11% 21% 19% 5%	2038
	11th to 20th	Day	36% 4 9% 25% 23% 3	1980
	21st to end	Day	36% 2 7% 29% 23% 3	1980
October	1st to 10th	Day	33% 3 8% 27% 25% 4	1980
	11th to 20th	Day	38% 2 8% 27% 21% 4	1836
	21st to end	Day	45% 2 9% 24% 16% 3	1871
November	1st to 10th	Day	35% 2 7% 28% 25% 4	1672
	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% 20% 20% 7%	1738
	21st to end	Night	45% 3 11% 24% 14% 3	1620
May	1st to 10th	Night	49% 4 11% 23% 10% 3	1620
	11th to 20th	Night	47% 5% 13% 21% 13% 2	1593
	21st to end	Night	36% 5% 17% 22% 17% 3	1745
June	1st to 10th	Night	31% 4 14% 30% 17% 4	1620
	11th to 20th	Night	31% 5% 16% 25% 20% 3	1579
	21st to end	Night	31% 6% 17% 24% 16% 5%	1440
July	1st to 10th	Night	40% 5% 12% 23% 16% 4	1425
	11th to 20th	Night	29% 5% 17% 26% 19% 4	1566
	21st to end	Night	33% 5% 14% 30% 17% 2	1672
August	1st to 10th	Night	30% 5% 17% 28% 18% 2	1600
	11th to 20th	Night	34% 5% 14% 29% 17% 2	1598
	21st to end	Night	28% 4 14% 29% 20% 5%	1980
September	1st to 10th	Night	33% 3 14% 24% 19% 6%	1903
	11th to 20th	Night	32% 3 9% 27% 26% 3	1980
	21st to end	Night	34% 3 7% 26% 26% 4	1980
October	1st to 10th	Night	29% 3 9% 28% 25% 5%	1980
	11th to 20th	Night	39% 3 7% 25% 22% 4	2124
	21st to end	Night	44% 2 6% 24% 20% 4	2483
November	1st to 10th	Night	36% 3 7% 26% 25% 4	2406
	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	19% 12% 28% 24% 14% 2	457
	11th to 20th	Day	19% 11% 28% 23% 14% 6%	412
	21st to end	Day	22% 8% 29% 25% 11% 4	420
May	1st to 10th	Day	20% 6% 29% 25% 14% 6%	423
	11th to 20th	Day	19% 3 20% 29% 20% 8%	447
	21st to end	Day	14% 1 18% 26% 22% 18%	485
June	1st to 10th	Day	14% 2 14% 25% 28% 17%	450
	11th to 20th	Day	11% 2 16% 30% 28% 14%	482
	21st to end	Day	10% 3 16% 33% 24% 14%	630
July	1st to 10th	Day	17% 1 9% 22% 24% 27%	587
	11th to 20th	Day	9% 2 11% 25% 30% 23%	444
	21st to end	Day	13% 1 9% 26% 31% 22%	488
August	1st to 10th	Day	14% 1 9% 23% 30% 24%	446
	11th to 20th	Day	13% 1 7% 29% 32% 18%	439
	21st to end	Day	11% 1 9% 24% 34% 22%	495
September	1st to 10th	Day	17% 1 8% 24% 28% 21%	450
	11th to 20th	Day	12% 1 8% 22% 34% 22%	450
	21st to end	Day	15% 4 17% 23% 30% 11%	450
October	1st to 10th	Day	11% 2 17% 35% 24% 11%	450
	11th to 20th	Day	14% 8% 28% 31% 15% 5%	450
	21st to end	Day	23% 6% 29% 27% 13% 2	386
November	1st to 10th	Day	16% 4 30% 28% 16% 6%	270
	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	533
	21st to end	Night	19% 4 31% 33% 11% 1	540
May	1st to 10th	Night	19% 3 26% 35% 14% 3	540
	11th to 20th	Night	16% 3 17% 39% 22% 2	531
	21st to end	Night	9% 2 14% 38% 31% 6%	584
June	1st to 10th	Night	10% 14% 44% 29% 4	540
	11th to 20th	Night	9% 1 11% 40% 34% 4	540
	21st to end	Night	8% 1 13% 45% 31% 4	540
July	1st to 10th	Night	13% 1 8% 30% 34% 14%	525
	11th to 20th	Night	8% 1 8% 36% 43% 5%	522
	21st to end	Night	11% 1 8% 37% 38% 6%	591
August	1st to 10th	Night	9% 1 5% 36% 43% 6%	537
	11th to 20th	Night	9% 6% 35% 43% 7%	534
	21st to end	Night	8% 5% 35% 44% 8%	594
September	1st to 10th	Night	14% 1 6% 32% 40% 6%	643
	11th to 20th	Night	13% 2 9% 30% 39% 8%	720
	21st to end	Night	15% 3 15% 33% 31% 3	720
October	1st to 10th	Night	11% 3 17% 35% 29% 6%	720
	11th to 20th	Night	16% 4 25% 37% 16% 2	720
	21st to end	Night	22% 6% 27% 30% 13% 2	792
November	1st to 10th	Night	16% 6% 23% 35% 19% 2	740
	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 2024-04-07 09:28:10. Version ac07

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