AngelKillarney s City
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the AngelKillarney s City clear sky chart from 2005-11-06 to 2026-09-29.

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	7% 3 1 3 2 2 2 2 4 5% 69%	157523
	Night	9% 4 1 3 2 2 3 2 4 5% 64%	151398
Transparency	Day	21% 2 6% 18% 27% 27%	152495
	Night	25% 2 7% 19% 25% 22%	147410
Seeing	Day	9% 8% 25% 34% 18% 6%	17708
	Night	11% 3 13% 39% 28% 7%	27039

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	20% 5% 2 4 3 3 2 2 5% 6% 48%	4722
	11th to 20th	Day	11% 5% 1 4 3 3 2 2 3 4 61%	5193
	21st to end	Day	13% 6% 2 6% 4 4 4 4 6% 8% 44%	5843
February	1st to 10th	Day	20% 6% 2 4 3 2 3 4 3 5% 48%	1890
	11th to 20th	Day	15% 7% 2 5% 4 3 4 3 5% 7% 45%	2041
	21st to end	Day	18% 6% 2 5% 4 3 4 3 5% 6% 45%	1730
March	1st to 10th	Day	16% 9% 3 7% 4 4 4 4 6% 6% 36%	4677
	11th to 20th	Day	16% 5% 1 4 2 3 4 3 5% 6% 50%	5110
	21st to end	Day	16% 6% 3 6% 4 4 4 4 6% 8% 40%	5876
April	1st to 10th	Day	13% 5% 2 4 3 3 4 3 5% 7% 51%	2520
	11th to 20th	Day	11% 4 2 4 3 3 3 2 5% 7% 57%	2489
	21st to end	Day	8% 5% 1 3 2 3 3 3 4 5% 62%	2520
May	1st to 10th	Day	6% 3 1 3 2 2 2 2 3 5% 71%	7131
	11th to 20th	Day	2 1 1 2 1 1 2 2 3 5% 81%	8025
	21st to end	Day	3 2 1 2 1 2 2 2 3 4 79%	8992
June	1st to 10th	Day	3 2 1 3 3 2 2 3 4 6% 70%	2940
	11th to 20th	Day	1 1 1 1 1 2 1 2 4 84%	2940
	21st to end	Day	2 2 1 1 1 1 1 2 2 85%	2940
July	1st to 10th	Day	1 1 1 1 1 1 2 92%	8219
	11th to 20th	Day	2 2 1 2 1 1 2 2 2 3 82%	8220
	21st to end	Day	1 1 1 1 1 1 2 3 89%	8365
August	1st to 10th	Day	1 1 1 1 1 1 1 2 2 88%	7477
	11th to 20th	Day	1 1 1 1 1 2 3 4 86%	7001
	21st to end	Day	2 2 1 2 1 2 2 2 3 5% 78%	7750
September	1st to 10th	Day	2 1 1 1 1 1 1 2 3 87%	2520
	11th to 20th	Day	2 1 1 2 1 2 2 2 3 5% 78%	2515
	21st to end	Day	3 1 1 2 1 1 2 1 3 4 80%	2279
October	1st to 10th	Day	3 2 1 2 2 1 2 2 4 5% 76%	3280
	11th to 20th	Day	4 2 2 2 2 2 2 3 3 79%	3261
	21st to end	Day	5% 2 1 3 3 3 3 3 5% 6% 67%	3558
November	1st to 10th	Day	9% 4 1 3 3 3 4 3 5% 7% 57%	1876
	11th to 20th	Day	11% 4 1 5% 3 3 3 4 4 6% 55%	1890
	21st to end	Day	12% 4 2 4 2 3 3 2 5% 6% 57%	1833
December	1st to 10th	Day	9% 2 1 4 3 4 3 2 4 7% 60%	2700
	11th to 20th	Day	26% 7% 2 5% 3 3 3 2 5% 7% 38%	3108
	21st to end	Day	20% 7% 3 6% 4 4 5% 4 7% 8% 32%	4092
January	1st to 10th	Night	19% 6% 2 4 3 3 3 3 5% 8% 46%	8172
	11th to 20th	Night	11% 4 1 3 2 3 3 3 4 5% 60%	7786
	21st to end	Night	14% 6% 2 6% 4 4 4 3 4 6% 48%	8371
February	1st to 10th	Night	17% 7% 2 5% 4 2 3 2 4 5% 50%	2730
	11th to 20th	Night	17% 6% 1 3 4 3 3 3 5% 6% 48%	2464
	21st to end	Night	17% 7% 1 4 3 3 3 2 4 5% 50%	2076
March	1st to 10th	Night	19% 9% 2 5% 4 4 4 3 5% 6% 39%	5434
	11th to 20th	Night	18% 8% 2 4 2 3 3 2 3 5% 50%	5110
	21st to end	Night	20% 8% 2 4 3 3 4 3 5% 7% 42%	5327
April	1st to 10th	Night	13% 4 2 5% 3 3 4 4 5% 7% 52%	2100
	11th to 20th	Night	11% 4 1 4 3 3 4 3 4 6% 59%	2079
	21st to end	Night	8% 4 1 3 3 2 3 3 4 6% 62%	2100
May	1st to 10th	Night	4 4 1 3 2 2 3 2 3 5% 71%	5826
	11th to 20th	Night	2 1 2 2 2 1 2 2 4 81%	4824
	21st to end	Night	2 1 1 2 1 1 2 2 3 4 82%	5181
June	1st to 10th	Night	4 2 1 2 2 1 2 3 3 7% 73%	1680
	11th to 20th	Night	1 1 1 2 2 3 4 86%	1680
	21st to end	Night	1 1 2 1 1 1 1 2 3 86%	1680
July	1st to 10th	Night	1 1 1 1 1 1 94%	4740
	11th to 20th	Night	3 3 1 2 2 2 2 1 3 3 79%	4740
	21st to end	Night	1 1 2 1 1 2 1 2 3 85%	5736
August	1st to 10th	Night	1 1 1 1 1 1 1 2 2 3 86%	5333
	11th to 20th	Night	1 1 1 1 2 2 3 5% 84%	5886
	21st to end	Night	2 1 1 2 1 2 2 2 3 5% 79%	6499
September	1st to 10th	Night	1 1 1 1 1 1 1 1 3 88%	2100
	11th to 20th	Night	2 2 1 2 1 1 2 2 3 4 81%	2103
	21st to end	Night	2 2 1 2 1 2 1 1 3 4 82%	2296
October	1st to 10th	Night	3 2 1 2 1 2 2 2 3 4 79%	3920
	11th to 20th	Night	3 1 1 2 1 2 2 1 3 4 81%	3897
	21st to end	Night	6% 3 1 3 2 2 3 2 4 6% 68%	4253
November	1st to 10th	Night	11% 4 1 3 2 2 2 2 4 7% 62%	2640
	11th to 20th	Night	11% 4 2 4 3 3 2 3 5% 7% 57%	2730
	21st to end	Night	11% 4 1 4 3 3 3 2 4 6% 58%	2783
December	1st to 10th	Night	9% 3 1 3 2 2 4 3 5% 6% 62%	4700
	11th to 20th	Night	24% 6% 2 5% 3 3 3 3 6% 10% 35%	5316
	21st to end	Night	20% 8% 3 8% 5% 5% 5% 4 5% 6% 30%	7106

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	39% 2 14% 25% 15% 5%	4723
	11th to 20th	Day	30% 1 5% 14% 27% 23%	5193
	21st to end	Day	38% 2 7% 19% 25% 8%	5843
February	1st to 10th	Day	40% 1 7% 24% 17% 11%	1890
	11th to 20th	Day	39% 2 8% 22% 23% 5%	2051
	21st to end	Day	42% 3 8% 24% 18% 6%	1730
March	1st to 10th	Day	48% 2 10% 19% 18% 3	4677
	11th to 20th	Day	35% 3 13% 31% 11% 7%	5110
	21st to end	Day	42% 3 12% 28% 13% 2	5876
April	1st to 10th	Day	34% 3 11% 25% 19% 7%	2520
	11th to 20th	Day	29% 3 12% 30% 19% 7%	2492
	21st to end	Day	26% 2 9% 32% 26% 4	2520
May	1st to 10th	Day	19% 2 6% 27% 34% 12%	7131
	11th to 20th	Day	9% 1 4 24% 44% 17%	8028
	21st to end	Day	12% 2 5% 20% 51% 10%	8994
June	1st to 10th	Day	17% 3 7% 22% 33% 18%	2940
	11th to 20th	Day	8% 1 4 19% 35% 33%	2940
	21st to end	Day	9% 1 1 8% 32% 48%	2940
July	1st to 10th	Day	4 1 4 18% 73%	8151
	11th to 20th	Day	9% 1 2 5% 11% 71%	8145
	21st to end	Day	5% 1 1 8% 28% 58%	8178
August	1st to 10th	Day	7% 1 1 4 24% 63%	5917
	11th to 20th	Day	6% 2 2 15% 32% 43%	5517
	21st to end	Day	11% 2 2 12% 36% 38%	6077
September	1st to 10th	Day	6% 1 2 9% 28% 54%	2520
	11th to 20th	Day	11% 2 2 20% 40% 25%	2515
	21st to end	Day	12% 1 2 18% 37% 30%	2279
October	1st to 10th	Day	12% 1 4 11% 21% 50%	3280
	11th to 20th	Day	14% 1 4 19% 40% 23%	3261
	21st to end	Day	19% 2 5% 17% 40% 17%	3558
November	1st to 10th	Day	28% 2 8% 25% 24% 13%	1876
	11th to 20th	Day	31% 2 10% 22% 25% 10%	1890
	21st to end	Day	30% 2 7% 22% 27% 12%	1833
December	1st to 10th	Day	26% 2 8% 28% 25% 11%	2700
	11th to 20th	Day	49% 2 8% 17% 17% 7%	3108
	21st to end	Day	50% 3 14% 21% 8% 4	4092
January	1st to 10th	Night	39% 2 17% 23% 15% 4	8172
	11th to 20th	Night	29% 1 7% 16% 30% 18%	7786
	21st to end	Night	39% 2 6% 19% 24% 10%	8371
February	1st to 10th	Night	39% 2 7% 21% 21% 10%	2730
	11th to 20th	Night	37% 2 9% 25% 18% 9%	2465
	21st to end	Night	38% 2 11% 24% 19% 6%	2076
March	1st to 10th	Night	47% 2 8% 21% 15% 7%	5434
	11th to 20th	Night	39% 3 9% 27% 13% 8%	5110
	21st to end	Night	43% 3 13% 25% 13% 3	5327
April	1st to 10th	Night	32% 3 14% 23% 21% 7%	2100
	11th to 20th	Night	28% 4 13% 27% 19% 9%	2079
	21st to end	Night	24% 3 11% 33% 22% 6%	2100
May	1st to 10th	Night	18% 3 9% 28% 28% 14%	5824
	11th to 20th	Night	10% 2 5% 26% 43% 15%	4824
	21st to end	Night	10% 2 5% 29% 48% 6%	5182
June	1st to 10th	Night	14% 2 11% 25% 33% 15%	1680
	11th to 20th	Night	5% 2 5% 22% 34% 32%	1680
	21st to end	Night	8% 1 1 12% 31% 48%	1680
July	1st to 10th	Night	3 1 4 22% 70%	4700
	11th to 20th	Night	13% 1 2 5% 11% 68%	4692
	21st to end	Night	8% 1 1 8% 28% 54%	5611
August	1st to 10th	Night	8% 1 1 5% 22% 62%	4215
	11th to 20th	Night	8% 2 2 16% 31% 42%	4636
	21st to end	Night	12% 1 1 15% 33% 39%	5092
September	1st to 10th	Night	6% 1 2 8% 29% 54%	2100
	11th to 20th	Night	11% 1 2 18% 40% 28%	2103
	21st to end	Night	10% 2 2 17% 38% 30%	2296
October	1st to 10th	Night	12% 2 3 12% 20% 52%	3920
	11th to 20th	Night	11% 1 3 25% 37% 23%	3897
	21st to end	Night	19% 2 4 18% 36% 21%	4253
November	1st to 10th	Night	25% 2 9% 26% 21% 18%	2640
	11th to 20th	Night	28% 2 8% 24% 25% 12%	2730
	21st to end	Night	29% 3 6% 22% 28% 12%	2783
December	1st to 10th	Night	25% 2 8% 26% 27% 12%	4700
	11th to 20th	Night	46% 3 10% 16% 19% 6%	5316
	21st to end	Night	53% 3 12% 20% 8% 5%	7106

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	28% 15% 20% 22% 13% 3	220
	11th to 20th	Day	17% 6% 19% 29% 21% 7%	374
	21st to end	Day	18% 6% 22% 28% 22% 4	473
February	1st to 10th	Day	22% 12% 20% 24% 17% 5%	430
	11th to 20th	Day	21% 10% 30% 26% 12% 2	531
	21st to end	Day	15% 13% 26% 33% 11% 1	446
March	1st to 10th	Day	22% 12% 28% 27% 10% 1	540
	11th to 20th	Day	20% 13% 27% 20% 16% 4	540
	21st to end	Day	18% 13% 29% 26% 12% 2	594
April	1st to 10th	Day	15% 15% 30% 24% 12% 4	540
	11th to 20th	Day	15% 16% 28% 27% 11% 4	532
	21st to end	Day	8% 14% 31% 30% 13% 4	540
May	1st to 10th	Day	8% 17% 26% 31% 12% 6%	543
	11th to 20th	Day	8% 13% 30% 31% 13% 5%	568
	21st to end	Day	6% 11% 26% 34% 17% 6%	617
June	1st to 10th	Day	3 9% 29% 36% 14% 8%	570
	11th to 20th	Day	2 10% 31% 38% 14% 5%	570
	21st to end	Day	2 6% 28% 38% 18% 8%	570
July	1st to 10th	Day	1 2 28% 43% 18% 8%	566
	11th to 20th	Day	1 1 19% 48% 22% 8%	564
	21st to end	Day	1 1 19% 49% 22% 8%	619
August	1st to 10th	Day	3 3 19% 47% 20% 9%	567
	11th to 20th	Day	1 3 25% 41% 21% 8%	557
	21st to end	Day	1 3 21% 46% 21% 7%	627
September	1st to 10th	Day	3 3 25% 42% 23% 4	570
	11th to 20th	Day	4 6% 29% 36% 21% 4	570
	21st to end	Day	3 6% 25% 39% 24% 4	563
October	1st to 10th	Day	5% 10% 24% 33% 22% 7%	530
	11th to 20th	Day	7% 7% 21% 32% 26% 6%	530
	21st to end	Day	7% 7% 23% 32% 25% 5%	583
November	1st to 10th	Day	11% 8% 17% 28% 28% 9%	352
	11th to 20th	Day	14% 8% 20% 32% 21% 6%	330
	21st to end	Day	13% 5% 21% 30% 26% 4	300
December	1st to 10th	Day	14% 6% 22% 29% 19% 10%	220
	11th to 20th	Day	19% 7% 22% 25% 20% 7%	220
	21st to end	Day	25% 10% 19% 25% 15% 5%	242
January	1st to 10th	Night	21% 4 16% 33% 18% 8%	840
	11th to 20th	Night	15% 4 12% 37% 25% 7%	840
	21st to end	Night	19% 4 13% 36% 21% 7%	924
February	1st to 10th	Night	20% 3 15% 37% 19% 6%	840
	11th to 20th	Night	20% 5% 16% 33% 19% 7%	824
	21st to end	Night	20% 5% 16% 41% 15% 3	692
March	1st to 10th	Night	22% 6% 17% 33% 19% 4	840
	11th to 20th	Night	19% 5% 16% 30% 24% 6%	840
	21st to end	Night	18% 6% 18% 36% 20% 3	924
April	1st to 10th	Night	14% 4 15% 43% 23% 2	840
	11th to 20th	Night	10% 6% 17% 39% 21% 6%	831
	21st to end	Night	10% 3 17% 40% 24% 6%	840
May	1st to 10th	Night	6% 4 19% 41% 24% 6%	811
	11th to 20th	Night	5% 3 15% 42% 33% 2	462
	21st to end	Night	4 2 14% 42% 36% 2	455
June	1st to 10th	Night	5% 1 13% 42% 35% 4	420
	11th to 20th	Night	1 13% 47% 35% 3	420
	21st to end	Night	1 10% 48% 37% 3	420
July	1st to 10th	Night	6% 45% 47% 3	410
	11th to 20th	Night	2 1 5% 45% 42% 5%	408
	21st to end	Night	1 1 5% 38% 46% 9%	659
August	1st to 10th	Night	2 4 36% 48% 8%	647
	11th to 20th	Night	1 7% 45% 38% 9%	832
	21st to end	Night	2 6% 44% 42% 6%	924
September	1st to 10th	Night	1 1 8% 42% 40% 8%	840
	11th to 20th	Night	3 1 10% 42% 35% 9%	840
	21st to end	Night	2 1 10% 41% 35% 10%	832
October	1st to 10th	Night	5% 2 10% 46% 30% 8%	800
	11th to 20th	Night	6% 3 11% 39% 33% 9%	800
	21st to end	Night	6% 2 12% 39% 26% 15%	880
November	1st to 10th	Night	11% 3 10% 37% 29% 10%	820
	11th to 20th	Night	12% 3 16% 39% 22% 8%	840
	21st to end	Night	13% 2 13% 39% 25% 8%	840
December	1st to 10th	Night	17% 3 12% 37% 24% 7%	840
	11th to 20th	Night	24% 3 12% 36% 20% 5%	840
	21st to end	Night	24% 3 19% 33% 18% 4	924

Page generated at 2026-09-26 01:18:39. Version ac07

Copyright © 2026 Attilla Danko.