Nicholia
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Nicholia clear sky chart from 2005-11-06 to 2026-08-15.

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	3 6% 3 8% 5% 5% 5% 5% 6% 7% 46%	152218
	Night	2 5% 3 7% 5% 5% 5% 4 7% 8% 48%	147057
Transparency	Day	32% 8% 12% 22% 19% 8%	146918
	Night	29% 8% 13% 25% 19% 7%	143364
Seeing	Day	8% 16% 32% 28% 12% 3	17503
	Night	5% 9% 28% 38% 16% 3	26924

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	5% 4 14% 9% 7% 7% 6% 8% 10% 31%	4660
	11th to 20th	Day	4 2 6% 7% 5% 6% 4 6% 8% 52%	4740
	21st to end	Day	7% 3 10% 6% 6% 6% 4 5% 7% 46%	5519
February	1st to 10th	Day	1 7% 4 12% 8% 6% 8% 6% 8% 7% 34%	1890
	11th to 20th	Day	1 6% 4 11% 9% 7% 8% 6% 7% 10% 30%	1903
	21st to end	Day	6% 4 12% 9% 8% 8% 7% 7% 9% 29%	1730
March	1st to 10th	Day	5% 4 10% 6% 6% 6% 5% 7% 9% 43%	4742
	11th to 20th	Day	1 9% 4 9% 5% 4 5% 4 7% 7% 44%	5110
	21st to end	Day	1 11% 6% 13% 8% 8% 8% 6% 8% 8% 23%	5607
April	1st to 10th	Day	3 11% 4 10% 7% 6% 6% 5% 8% 10% 33%	2431
	11th to 20th	Day	2 10% 3 8% 6% 6% 6% 5% 7% 8% 38%	2697
	21st to end	Day	4 11% 4 9% 6% 7% 6% 5% 8% 8% 32%	2730
May	1st to 10th	Day	2 7% 3 6% 4 4 6% 5% 7% 9% 46%	7626
	11th to 20th	Day	5% 10% 3 8% 5% 5% 5% 4 6% 8% 41%	7596
	21st to end	Day	6% 10% 4 7% 4 5% 5% 4 6% 8% 42%	9101
June	1st to 10th	Day	7% 8% 3 8% 6% 5% 5% 5% 8% 9% 36%	3150
	11th to 20th	Day	7% 9% 3 6% 5% 5% 4 3 6% 8% 44%	3150
	21st to end	Day	3 5% 2 5% 5% 5% 4 4 6% 6% 55%	3150
July	1st to 10th	Day	2 3 2 4 4 4 5% 4 6% 7% 58%	8643
	11th to 20th	Day	3 4 2 5% 4 5% 5% 4 6% 7% 54%	8220
	21st to end	Day	4 4 2 6% 5% 6% 6% 5% 7% 7% 48%	8646
August	1st to 10th	Day	4 4 2 6% 5% 5% 6% 5% 7% 7% 48%	5909
	11th to 20th	Day	2 2 1 4 4 4 4 4 6% 7% 62%	5851
	21st to end	Day	5% 5% 2 6% 4 4 4 3 5% 5% 56%	6468
September	1st to 10th	Day	5% 4 2 5% 2 4 4 3 5% 6% 61%	2319
	11th to 20th	Day	7% 8% 3 5% 3 5% 5% 3 6% 6% 50%	2200
	21st to end	Day	7% 6% 2 5% 4 3 3 3 4 7% 57%	2200
October	1st to 10th	Day	5% 6% 2 6% 5% 4 3 3 4 5% 58%	3478
	11th to 20th	Day	3 6% 2 5% 3 3 3 3 5% 6% 59%	3250
	21st to end	Day	2 7% 3 8% 4 5% 7% 4 5% 7% 47%	3246
November	1st to 10th	Day	3 9% 4 9% 7% 6% 5% 5% 6% 8% 38%	1854
	11th to 20th	Day	2 7% 4 11% 7% 7% 5% 6% 7% 8% 37%	1795
	21st to end	Day	1 8% 3 10% 5% 6% 6% 6% 6% 8% 42%	1680
December	1st to 10th	Day	1 4 3 7% 5% 5% 4 5% 5% 6% 55%	2637
	11th to 20th	Day	1 8% 6% 13% 8% 7% 7% 5% 8% 8% 29%	2715
	21st to end	Day	1 9% 4 12% 8% 6% 7% 4 7% 7% 34%	3575
January	1st to 10th	Night	6% 4 12% 7% 6% 7% 6% 8% 10% 34%	8289
	11th to 20th	Night	3 2 8% 7% 6% 5% 4 6% 9% 49%	8220
	21st to end	Night	6% 3 8% 6% 6% 5% 4 6% 8% 48%	8676
February	1st to 10th	Night	1 9% 4 11% 8% 7% 7% 6% 6% 9% 33%	2730
	11th to 20th	Night	1 7% 4 10% 7% 6% 7% 5% 7% 9% 36%	2603
	21st to end	Night	1 6% 2 9% 8% 8% 7% 7% 9% 9% 33%	2076
March	1st to 10th	Night	6% 4 11% 5% 5% 5% 4 6% 9% 45%	5370
	11th to 20th	Night	1 9% 3 8% 5% 5% 6% 5% 8% 7% 44%	5110
	21st to end	Night	1 7% 4 9% 7% 6% 7% 6% 8% 11% 33%	5610
April	1st to 10th	Night	2 10% 3 8% 6% 6% 7% 5% 7% 8% 38%	2185
	11th to 20th	Night	3 6% 2 7% 7% 7% 6% 5% 8% 10% 40%	1871
	21st to end	Night	4 9% 4 9% 6% 6% 5% 4 6% 8% 39%	1890
May	1st to 10th	Night	2 5% 3 6% 4 4 5% 4 6% 7% 54%	5321
	11th to 20th	Night	4 8% 3 6% 4 4 4 4 6% 8% 48%	5296
	21st to end	Night	5% 7% 3 6% 4 4 4 4 6% 8% 49%	5067
June	1st to 10th	Night	5% 6% 2 7% 6% 5% 4 4 7% 10% 43%	1470
	11th to 20th	Night	6% 5% 2 6% 4 4 5% 4 5% 8% 51%	1470
	21st to end	Night	3 4 2 4 3 4 5% 3 6% 7% 60%	1470
July	1st to 10th	Night	1 1 2 2 3 4 4 7% 8% 68%	4311
	11th to 20th	Night	1 2 1 3 2 3 3 3 6% 8% 68%	4740
	21st to end	Night	2 2 1 4 3 4 5% 4 6% 8% 62%	5441
August	1st to 10th	Night	2 2 1 4 4 4 6% 4 7% 9% 58%	4123
	11th to 20th	Night	1 1 1 3 2 3 3 3 5% 6% 72%	4087
	21st to end	Night	6% 5% 1 4 3 3 3 3 4 6% 63%	4509
September	1st to 10th	Night	4 4 1 3 2 3 4 3 5% 6% 65%	2077
	11th to 20th	Night	4 4 1 6% 4 4 4 3 5% 7% 58%	2200
	21st to end	Night	6% 5% 2 4 3 3 3 3 4 6% 62%	2200
October	1st to 10th	Night	3 4 1 4 3 3 3 3 5% 7% 63%	3718
	11th to 20th	Night	3 7% 3 6% 4 4 4 3 5% 6% 55%	3898
	21st to end	Night	2 6% 3 7% 4 5% 5% 5% 8% 8% 46%	4537
November	1st to 10th	Night	2 8% 3 8% 6% 6% 5% 5% 8% 9% 40%	2665
	11th to 20th	Night	1 8% 4 8% 6% 6% 6% 5% 8% 9% 39%	2802
	21st to end	Night	1 6% 3 8% 6% 6% 5% 5% 8% 8% 43%	2940
December	1st to 10th	Night	1 4 2 6% 6% 5% 4 4 6% 8% 54%	4766
	11th to 20th	Night	1 7% 4 12% 8% 7% 8% 6% 8% 10% 30%	5696
	21st to end	Night	1 7% 4 12% 8% 7% 7% 6% 8% 8% 31%	7623

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	40% 13% 18% 17% 12%	4661
	11th to 20th	Day	25% 9% 16% 28% 14% 8%	4740
	21st to end	Day	36% 6% 13% 18% 21% 6%	5519
February	1st to 10th	Day	39% 13% 20% 18% 9% 1	1890
	11th to 20th	Day	40% 12% 19% 18% 9% 2	1912
	21st to end	Day	40% 14% 17% 18% 9% 3	1730
March	1st to 10th	Day	32% 8% 16% 21% 17% 6%	4742
	11th to 20th	Day	32% 9% 16% 29% 14% 1	5110
	21st to end	Day	46% 13% 18% 18% 4	5607
April	1st to 10th	Day	39% 10% 19% 22% 9%	2431
	11th to 20th	Day	36% 8% 18% 24% 13% 1	2700
	21st to end	Day	40% 8% 17% 26% 8%	2730
May	1st to 10th	Day	26% 9% 13% 31% 19% 2	7626
	11th to 20th	Day	35% 8% 9% 24% 18% 6%	7599
	21st to end	Day	36% 8% 11% 29% 16% 1	9102
June	1st to 10th	Day	40% 7% 17% 25% 10% 1	3150
	11th to 20th	Day	37% 6% 9% 21% 20% 8%	3150
	21st to end	Day	26% 5% 8% 23% 30% 7%	3150
July	1st to 10th	Day	21% 6% 5% 16% 27% 25%	8572
	11th to 20th	Day	25% 6% 5% 16% 23% 25%	8145
	21st to end	Day	28% 8% 5% 12% 30% 17%	8453
August	1st to 10th	Day	32% 7% 6% 14% 28% 12%	4338
	11th to 20th	Day	19% 6% 5% 19% 36% 15%	4250
	21st to end	Day	25% 5% 5% 20% 28% 17%	4663
September	1st to 10th	Day	22% 5% 6% 20% 30% 16%	2319
	11th to 20th	Day	31% 6% 9% 20% 25% 8%	2200
	21st to end	Day	27% 4 11% 26% 24% 8%	2200
October	1st to 10th	Day	27% 4 8% 22% 31% 7%	3478
	11th to 20th	Day	24% 5% 15% 32% 19% 5%	3250
	21st to end	Day	31% 8% 12% 25% 23% 2	3246
November	1st to 10th	Day	40% 9% 15% 21% 14% 1	1854
	11th to 20th	Day	38% 10% 19% 24% 8% 2	1795
	21st to end	Day	35% 8% 20% 22% 12% 4	1680
December	1st to 10th	Day	26% 8% 19% 26% 19% 3	2637
	11th to 20th	Day	45% 10% 18% 18% 8% 1	2714
	21st to end	Day	43% 11% 11% 18% 11% 6%	3575
January	1st to 10th	Night	37% 12% 13% 23% 15% 1	8290
	11th to 20th	Night	26% 10% 12% 32% 15% 6%	8220
	21st to end	Night	32% 7% 14% 19% 20% 9%	8676
February	1st to 10th	Night	42% 11% 18% 18% 11% 1	2730
	11th to 20th	Night	38% 10% 19% 20% 10% 2	2604
	21st to end	Night	37% 12% 15% 23% 10% 3	2076
March	1st to 10th	Night	32% 8% 12% 23% 15% 9%	5370
	11th to 20th	Night	31% 9% 14% 31% 15% 1	5110
	21st to end	Night	34% 12% 18% 29% 6% 1	5610
April	1st to 10th	Night	37% 10% 16% 25% 11% 1	2185
	11th to 20th	Night	33% 8% 18% 27% 13% 1	1871
	21st to end	Night	38% 8% 16% 28% 9%	1890
May	1st to 10th	Night	24% 6% 11% 35% 21% 2	5319
	11th to 20th	Night	29% 8% 9% 32% 19% 3	5297
	21st to end	Night	28% 8% 13% 33% 19%	5068
June	1st to 10th	Night	32% 8% 16% 31% 12% 1	1470
	11th to 20th	Night	29% 7% 12% 23% 22% 7%	1470
	21st to end	Night	22% 5% 10% 24% 30% 9%	1470
July	1st to 10th	Night	11% 4 6% 20% 30% 28%	4274
	11th to 20th	Night	13% 4 5% 25% 27% 27%	4692
	21st to end	Night	17% 6% 5% 21% 34% 17%	5322
August	1st to 10th	Night	20% 8% 7% 19% 31% 15%	3018
	11th to 20th	Night	16% 5% 6% 25% 30% 17%	2964
	21st to end	Night	16% 4 7% 24% 33% 16%	3245
September	1st to 10th	Night	18% 6% 7% 22% 30% 17%	2077
	11th to 20th	Night	25% 5% 10% 26% 25% 9%	2200
	21st to end	Night	24% 4 10% 27% 30% 5%	2200
October	1st to 10th	Night	18% 5% 10% 27% 32% 7%	3718
	11th to 20th	Night	27% 6% 13% 25% 23% 6%	3898
	21st to end	Night	29% 7% 14% 29% 20% 1	4537
November	1st to 10th	Night	35% 8% 15% 25% 15% 2	2665
	11th to 20th	Night	36% 9% 19% 24% 10% 2	2802
	21st to end	Night	34% 8% 15% 25% 14% 4	2940
December	1st to 10th	Night	24% 8% 22% 26% 18% 2	4766
	11th to 20th	Night	43% 11% 18% 19% 8% 1	5697
	21st to end	Night	41% 11% 13% 19% 10% 6%	7623

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	6% 15% 30% 35% 10% 5%	220
	11th to 20th	Day	4 13% 38% 28% 13% 5%	220
	21st to end	Day	8% 12% 35% 30% 13% 2	303
February	1st to 10th	Day	5% 22% 44% 22% 5% 2	330
	11th to 20th	Day	5% 18% 38% 26% 10% 2	388
	21st to end	Day	3 17% 39% 30% 10% 1	446
March	1st to 10th	Day	6% 18% 38% 30% 7% 1	540
	11th to 20th	Day	10% 14% 29% 34% 10% 1	540
	21st to end	Day	9% 20% 32% 28% 11% 1	594
April	1st to 10th	Day	8% 18% 31% 27% 13% 2	540
	11th to 20th	Day	7% 23% 38% 20% 9% 2	532
	21st to end	Day	10% 19% 31% 27% 11% 3	540
May	1st to 10th	Day	7% 18% 30% 30% 13% 2	543
	11th to 20th	Day	19% 16% 27% 25% 12% 2	568
	21st to end	Day	15% 12% 25% 30% 14% 5%	772
June	1st to 10th	Day	9% 13% 28% 29% 15% 5%	780
	11th to 20th	Day	15% 21% 30% 23% 9% 2	780
	21st to end	Day	7% 14% 31% 31% 15% 2	780
July	1st to 10th	Day	6% 12% 31% 30% 17% 4	714
	11th to 20th	Day	4 15% 38% 32% 10% 2	564
	21st to end	Day	6% 12% 36% 29% 14% 4	619
August	1st to 10th	Day	8% 13% 30% 32% 14% 3	567
	11th to 20th	Day	5% 12% 30% 31% 17% 6%	534
	21st to end	Day	7% 11% 34% 28% 16% 4	583
September	1st to 10th	Day	6% 12% 34% 27% 16% 6%	530
	11th to 20th	Day	10% 15% 30% 28% 13% 5%	530
	21st to end	Day	11% 15% 33% 24% 15% 3	530
October	1st to 10th	Day	12% 14% 32% 25% 13% 5%	460
	11th to 20th	Day	9% 22% 22% 23% 16% 7%	330
	21st to end	Day	9% 22% 32% 29% 7% 1	363
November	1st to 10th	Day	9% 20% 33% 25% 11% 2	330
	11th to 20th	Day	7% 17% 32% 33% 8% 2	330
	21st to end	Day	5% 11% 33% 38% 11% 2	330
December	1st to 10th	Day	5% 9% 35% 30% 16% 5%	311
	11th to 20th	Day	9% 14% 36% 29% 10% 2	220
	21st to end	Day	8% 18% 33% 27% 13% 2	242
January	1st to 10th	Night	3 9% 32% 42% 12% 2	882
	11th to 20th	Night	3 13% 31% 37% 12% 3	840
	21st to end	Night	4 11% 32% 39% 12% 2	924
February	1st to 10th	Night	4 13% 37% 35% 9% 2	840
	11th to 20th	Night	4 10% 37% 36% 11% 2	824
	21st to end	Night	3 8% 36% 38% 13% 2	692
March	1st to 10th	Night	3 9% 35% 41% 11% 1	840
	11th to 20th	Night	6% 9% 33% 34% 15% 3	840
	21st to end	Night	7% 13% 29% 36% 13% 1	924
April	1st to 10th	Night	6% 13% 30% 35% 13% 3	830
	11th to 20th	Night	6% 11% 37% 33% 12% 1	623
	21st to end	Night	9% 9% 28% 36% 14% 3	630
May	1st to 10th	Night	5% 11% 28% 35% 17% 3	630
	11th to 20th	Night	10% 6% 24% 34% 22% 3	621
	21st to end	Night	14% 8% 23% 31% 21% 3	581
June	1st to 10th	Night	7% 6% 22% 40% 22% 3	420
	11th to 20th	Night	8% 9% 26% 40% 15% 1	420
	21st to end	Night	4 2 20% 46% 26% 2	420
July	1st to 10th	Night	3 3 14% 48% 30% 3	410
	11th to 20th	Night	2 3 16% 55% 23% 2	408
	21st to end	Night	3 2 14% 49% 29% 4	556
August	1st to 10th	Night	5% 3 19% 46% 25% 3	627
	11th to 20th	Night	2 3 16% 49% 27% 3	606
	21st to end	Night	5% 5% 20% 39% 27% 4	660
September	1st to 10th	Night	6% 3 18% 39% 29% 6%	759
	11th to 20th	Night	6% 5% 16% 37% 30% 7%	800
	21st to end	Night	9% 6% 19% 36% 23% 7%	800
October	1st to 10th	Night	7% 6% 27% 37% 19% 4	800
	11th to 20th	Night	8% 10% 23% 37% 18% 5%	800
	21st to end	Night	7% 10% 30% 36% 13% 4	880
November	1st to 10th	Night	6% 8% 30% 39% 15% 3	820
	11th to 20th	Night	5% 9% 35% 40% 10% 1	912
	21st to end	Night	4 11% 34% 35% 13% 2	1050
December	1st to 10th	Night	5% 12% 33% 39% 10% 2	1050
	11th to 20th	Night	4 8% 36% 41% 10% 1	1050
	21st to end	Night	6% 13% 37% 33% 9% 1	1155

Page generated at 2026-08-12 01:37:16. Version ac07

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