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 2025-05-26.

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	8% 4 1 3 2 2 3 2 4 5% 66%	117981
	Night	10% 4 1 3 2 2 3 2 4 5% 62%	120150
Transparency	Day	23% 2 6% 18% 25% 25%	117732
	Night	27% 2 7% 20% 23% 21%	119988
Seeing	Day	10% 9% 25% 34% 18% 5%	15891
	Night	11% 3 12% 39% 28% 7%	25371

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	17% 5% 2 4 3 3 3 2 4 5% 53%	3639
	11th to 20th	Day	14% 6% 2 5% 4 4 3 2 3 4 54%	3981
	21st to end	Day	16% 7% 2 6% 4 4 4 3 5% 6% 44%	4510
February	1st to 10th	Day	20% 6% 2 4 3 2 3 4 3 5% 47%	1800
	11th to 20th	Day	15% 6% 2 5% 4 3 4 3 5% 7% 46%	1941
	21st to end	Day	18% 6% 2 5% 4 3 4 3 4 5% 45%	1650
March	1st to 10th	Day	16% 10% 3 7% 4 4 5% 4 6% 6% 35%	4576
	11th to 20th	Day	17% 5% 1 4 2 3 4 3 5% 6% 49%	5000
	21st to end	Day	16% 6% 3 6% 4 4 4 4 6% 8% 40%	5749
April	1st to 10th	Day	13% 5% 2 4 3 3 4 3 5% 7% 51%	2400
	11th to 20th	Day	11% 4 2 4 3 3 3 2 5% 7% 57%	2369
	21st to end	Day	8% 4 1 3 2 2 3 3 4 6% 63%	2400
May	1st to 10th	Day	6% 3 1 2 2 2 2 2 3 5% 72%	3969
	11th to 20th	Day	3 2 1 2 2 1 2 2 3 5% 79%	4443
	21st to end	Day	4 2 1 2 1 2 2 2 3 5% 77%	4886
June	1st to 10th	Day	4 3 1 3 3 3 2 3 4 6% 69%	2660
	11th to 20th	Day	1 1 2 1 2 2 1 3 4 83%	2660
	21st to end	Day	2 2 1 1 1 2 1 2 3 84%	2660
July	1st to 10th	Day	1 1 1 1 1 1 2 93%	4420
	11th to 20th	Day	1 1 2 1 2 2 2 2 4 84%	4420
	21st to end	Day	1 1 1 1 1 1 1 2 3 89%	4490
August	1st to 10th	Day	2 1 1 2 1 1 1 2 3 3 83%	4046
	11th to 20th	Day	1 1 1 1 1 2 4 89%	3724
	21st to end	Day	1 1 1 1 1 1 1 1 2 2 89%	4180
September	1st to 10th	Day	2 1 1 1 1 1 1 1 2 89%	2280
	11th to 20th	Day	2 1 1 2 1 2 2 2 4 5% 78%	2275
	21st to end	Day	3 1 1 2 1 1 1 1 3 4 81%	2081
October	1st to 10th	Day	3 2 1 2 2 1 2 2 4 5% 76%	3180
	11th to 20th	Day	3 2 2 2 2 2 2 3 3 79%	3161
	21st to end	Day	5% 2 1 3 2 3 3 3 5% 6% 67%	3448
November	1st to 10th	Day	9% 5% 2 4 3 3 4 3 5% 7% 56%	1785
	11th to 20th	Day	10% 4 1 5% 3 3 3 4 4 6% 57%	1800
	21st to end	Day	12% 5% 2 4 2 3 3 2 5% 6% 55%	1746
December	1st to 10th	Day	9% 3 1 4 3 4 3 2 4 7% 60%	2620
	11th to 20th	Day	26% 7% 2 5% 3 3 3 2 5% 7% 38%	3028
	21st to end	Day	20% 7% 3 6% 4 4 5% 4 7% 8% 32%	4004
January	1st to 10th	Night	12% 6% 2 4 3 3 3 3 5% 9% 51%	6306
	11th to 20th	Night	15% 5% 2 4 3 3 3 2 4 5% 54%	5990
	21st to end	Night	17% 6% 2 4 4 4 4 3 4 5% 48%	6468
February	1st to 10th	Night	18% 7% 2 5% 4 2 3 2 4 5% 49%	2600
	11th to 20th	Night	16% 6% 1 3 4 3 3 3 5% 7% 50%	2344
	21st to end	Night	17% 7% 1 4 3 3 3 2 4 5% 50%	1980
March	1st to 10th	Night	19% 9% 2 5% 4 4 4 3 5% 6% 39%	5315
	11th to 20th	Night	19% 8% 2 4 2 3 3 2 3 5% 49%	5000
	21st to end	Night	20% 8% 2 4 3 3 4 3 5% 7% 42%	5212
April	1st to 10th	Night	12% 4 2 5% 3 3 4 4 5% 7% 52%	2000
	11th to 20th	Night	10% 4 1 4 3 2 4 3 4 6% 59%	1979
	21st to end	Night	8% 4 1 3 3 2 3 3 4 6% 63%	2000
May	1st to 10th	Night	4 4 1 2 1 1 2 2 3 5% 74%	3226
	11th to 20th	Night	3 1 2 1 1 1 2 3 5% 80%	2668
	21st to end	Night	2 2 1 2 1 2 1 2 3 4 80%	2805
June	1st to 10th	Night	4 2 1 2 2 1 2 2 3 7% 72%	1520
	11th to 20th	Night	1 1 1 1 2 2 4 4 85%	1520
	21st to end	Night	1 1 2 1 1 1 1 3 3 85%	1520
July	1st to 10th	Night	1 1 1 1 1 94%	2540
	11th to 20th	Night	3 1 1 2 2 2 2 2 3 3 80%	2540
	21st to end	Night	1 2 1 2 1 2 1 2 3 84%	3067
August	1st to 10th	Night	2 2 1 2 1 1 2 2 4 4 79%	2879
	11th to 20th	Night	1 1 1 1 1 1 2 3 87%	3126
	21st to end	Night	2 1 1 1 1 1 1 1 2 89%	3498
September	1st to 10th	Night	1 1 1 1 1 1 1 1 2 90%	1900
	11th to 20th	Night	2 2 1 2 1 1 2 2 3 4 81%	1903
	21st to end	Night	2 2 2 1 2 1 1 2 4 84%	2097
October	1st to 10th	Night	3 2 1 2 1 2 2 2 3 4 79%	3800
	11th to 20th	Night	3 1 2 1 2 2 1 3 4 82%	3777
	21st to end	Night	6% 3 1 3 2 2 3 3 4 5% 69%	4121
November	1st to 10th	Night	11% 4 1 3 2 2 2 2 4 7% 61%	2511
	11th to 20th	Night	10% 4 2 4 3 3 2 3 5% 7% 59%	2600
	21st to end	Night	12% 5% 1 4 3 3 3 2 4 6% 57%	2650
December	1st to 10th	Night	9% 3 1 3 2 2 4 3 5% 6% 61%	4560
	11th to 20th	Night	24% 6% 2 5% 3 3 3 3 6% 10% 34%	5176
	21st to end	Night	19% 8% 3 8% 5% 5% 5% 4 6% 6% 31%	6952

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	35% 2 16% 24% 18% 6%	3639
	11th to 20th	Day	38% 1 6% 16% 24% 16%	3981
	21st to end	Day	41% 2 8% 15% 26% 7%	4510
February	1st to 10th	Day	41% 1 8% 24% 17% 10%	1800
	11th to 20th	Day	38% 3 8% 22% 24% 5%	1951
	21st to end	Day	42% 2 8% 24% 18% 6%	1650
March	1st to 10th	Day	48% 2 10% 19% 17% 3	4576
	11th to 20th	Day	36% 3 14% 31% 10% 7%	5000
	21st to end	Day	43% 3 12% 28% 13% 2	5749
April	1st to 10th	Day	34% 3 12% 26% 18% 7%	2400
	11th to 20th	Day	29% 3 12% 30% 20% 7%	2372
	21st to end	Day	25% 2 9% 32% 26% 5%	2400
May	1st to 10th	Day	18% 2 6% 30% 29% 16%	3969
	11th to 20th	Day	11% 1 4 25% 44% 14%	4446
	21st to end	Day	14% 2 6% 28% 42% 8%	4887
June	1st to 10th	Day	18% 3 8% 22% 32% 18%	2660
	11th to 20th	Day	9% 1 4 21% 35% 30%	2660
	21st to end	Day	9% 1 1 9% 31% 48%	2660
July	1st to 10th	Day	3 1 4 13% 79%	4351
	11th to 20th	Day	7% 2 2 5% 15% 68%	4345
	21st to end	Day	5% 1 1 4 22% 67%	4348
August	1st to 10th	Day	9% 1 1 6% 21% 62%	4031
	11th to 20th	Day	4 1 5% 29% 61%	3760
	21st to end	Day	6% 1 2 5% 33% 53%	4179
September	1st to 10th	Day	6% 1 1 6% 28% 58%	2280
	11th to 20th	Day	11% 2 2 20% 39% 25%	2275
	21st to end	Day	11% 1 2 17% 37% 32%	2081
October	1st to 10th	Day	12% 1 4 10% 21% 52%	3180
	11th to 20th	Day	13% 1 4 18% 41% 23%	3161
	21st to end	Day	19% 2 5% 17% 40% 18%	3448
November	1st to 10th	Day	29% 3 7% 25% 23% 13%	1785
	11th to 20th	Day	28% 2 10% 23% 26% 10%	1800
	21st to end	Day	31% 2 7% 21% 26% 12%	1746
December	1st to 10th	Day	26% 2 8% 27% 25% 11%	2620
	11th to 20th	Day	49% 2 8% 17% 18% 7%	3028
	21st to end	Day	49% 3 14% 21% 8% 4	4004
January	1st to 10th	Night	32% 2 18% 26% 16% 6%	6306
	11th to 20th	Night	36% 1 8% 16% 26% 12%	5990
	21st to end	Night	40% 2 7% 16% 24% 11%	6468
February	1st to 10th	Night	40% 2 7% 20% 21% 10%	2600
	11th to 20th	Night	36% 2 8% 26% 19% 9%	2345
	21st to end	Night	38% 2 10% 24% 20% 6%	1980
March	1st to 10th	Night	47% 2 8% 21% 15% 6%	5315
	11th to 20th	Night	40% 3 10% 27% 13% 8%	5000
	21st to end	Night	43% 3 13% 25% 12% 3	5212
April	1st to 10th	Night	32% 3 14% 23% 20% 6%	2000
	11th to 20th	Night	27% 4 13% 27% 20% 9%	1979
	21st to end	Night	23% 3 11% 33% 23% 7%	2000
May	1st to 10th	Night	16% 2 10% 29% 29% 16%	3226
	11th to 20th	Night	10% 1 7% 29% 38% 15%	2668
	21st to end	Night	11% 1 7% 36% 37% 7%	2805
June	1st to 10th	Night	15% 3 12% 25% 31% 15%	1520
	11th to 20th	Night	5% 2 6% 24% 34% 29%	1520
	21st to end	Night	8% 1 1 12% 30% 48%	1520
July	1st to 10th	Night	2 1 4 14% 79%	2500
	11th to 20th	Night	11% 2 2 5% 14% 66%	2492
	21st to end	Night	8% 1 1 4 23% 63%	2971
August	1st to 10th	Night	10% 2 1 7% 20% 60%	2870
	11th to 20th	Night	5% 1 6% 28% 59%	3156
	21st to end	Night	7% 1 8% 32% 51%	3498
September	1st to 10th	Night	5% 1 1 6% 28% 58%	1900
	11th to 20th	Night	11% 1 3 18% 41% 27%	1903
	21st to end	Night	9% 2 2 16% 41% 31%	2097
October	1st to 10th	Night	12% 2 3 11% 19% 54%	3800
	11th to 20th	Night	10% 1 3 25% 37% 23%	3777
	21st to end	Night	19% 2 4 17% 37% 21%	4121
November	1st to 10th	Night	25% 2 8% 25% 21% 19%	2511
	11th to 20th	Night	26% 2 8% 25% 26% 12%	2600
	21st to end	Night	30% 3 6% 21% 28% 12%	2650
December	1st to 10th	Night	25% 2 8% 25% 28% 12%	4560
	11th to 20th	Night	47% 3 10% 16% 19% 5%	5176
	21st to end	Night	53% 3 12% 20% 7% 5%	6952

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% 13% 21% 23% 14% 2	200
	11th to 20th	Day	19% 6% 21% 30% 18% 6%	346
	21st to end	Day	19% 6% 21% 28% 21% 5%	440
February	1st to 10th	Day	24% 12% 20% 23% 17% 5%	400
	11th to 20th	Day	20% 9% 30% 27% 12% 2	491
	21st to end	Day	16% 13% 26% 32% 12% 1	414
March	1st to 10th	Day	23% 12% 27% 26% 10% 1	500
	11th to 20th	Day	22% 14% 28% 19% 14% 3	500
	21st to end	Day	19% 14% 29% 25% 11% 2	550
April	1st to 10th	Day	16% 15% 31% 24% 12% 3	500
	11th to 20th	Day	14% 16% 29% 27% 10% 3	492
	21st to end	Day	8% 14% 30% 30% 13% 4	500
May	1st to 10th	Day	8% 18% 27% 31% 11% 5%	503
	11th to 20th	Day	8% 13% 30% 31% 13% 5%	528
	21st to end	Day	7% 12% 25% 34% 16% 7%	550
June	1st to 10th	Day	4 11% 29% 35% 13% 8%	490
	11th to 20th	Day	2 11% 31% 37% 14% 5%	490
	21st to end	Day	2 6% 28% 38% 18% 8%	490
July	1st to 10th	Day	1 2 26% 45% 18% 9%	486
	11th to 20th	Day	1 1 20% 48% 22% 9%	484
	21st to end	Day	1 1 20% 48% 21% 9%	531
August	1st to 10th	Day	3 3 20% 48% 18% 8%	487
	11th to 20th	Day	1 3 28% 41% 19% 8%	477
	21st to end	Day	1 3 23% 46% 20% 7%	539
September	1st to 10th	Day	2 3 24% 43% 23% 4	490
	11th to 20th	Day	3 6% 29% 38% 20% 4	490
	21st to end	Day	3 6% 23% 40% 24% 3	490
October	1st to 10th	Day	4 10% 23% 34% 23% 6%	490
	11th to 20th	Day	7% 7% 21% 33% 27% 6%	490
	21st to end	Day	6% 8% 24% 33% 24% 5%	539
November	1st to 10th	Day	11% 8% 17% 28% 28% 7%	321
	11th to 20th	Day	10% 8% 21% 32% 22% 6%	300
	21st to end	Day	14% 5% 22% 29% 25% 4	273
December	1st to 10th	Day	16% 7% 22% 29% 18% 10%	200
	11th to 20th	Day	21% 8% 23% 25% 18% 7%	200
	21st to end	Day	22% 10% 20% 26% 15% 5%	220
January	1st to 10th	Night	20% 3 16% 34% 19% 9%	800
	11th to 20th	Night	15% 4 13% 37% 24% 7%	800
	21st to end	Night	20% 4 13% 35% 21% 7%	880
February	1st to 10th	Night	20% 3 16% 36% 19% 6%	800
	11th to 20th	Night	18% 5% 16% 34% 20% 7%	784
	21st to end	Night	20% 5% 14% 41% 15% 3	660
March	1st to 10th	Night	23% 6% 15% 33% 19% 4	800
	11th to 20th	Night	20% 6% 16% 29% 23% 6%	800
	21st to end	Night	19% 6% 18% 35% 20% 3	880
April	1st to 10th	Night	14% 4 15% 43% 22% 2	800
	11th to 20th	Night	10% 6% 18% 39% 21% 6%	791
	21st to end	Night	9% 3 16% 40% 25% 6%	800
May	1st to 10th	Night	6% 4 19% 41% 23% 6%	772
	11th to 20th	Night	5% 3 15% 41% 33% 2	440
	21st to end	Night	4 2 13% 41% 38% 2	422
June	1st to 10th	Night	5% 1 12% 39% 38% 4	380
	11th to 20th	Night	1 13% 45% 37% 4	380
	21st to end	Night	2 1 8% 48% 39% 3	380
July	1st to 10th	Night	2 44% 51% 3	370
	11th to 20th	Night	1 1 4 43% 45% 5%	368
	21st to end	Night	1 1 4 37% 47% 10%	595
August	1st to 10th	Night	3 4 37% 47% 9%	585
	11th to 20th	Night	1 1 8% 44% 38% 10%	752
	21st to end	Night	2 5% 43% 44% 7%	836
September	1st to 10th	Night	1 1 6% 41% 43% 9%	760
	11th to 20th	Night	3 1 9% 41% 36% 10%	760
	21st to end	Night	3 1 9% 41% 36% 11%	760
October	1st to 10th	Night	5% 2 9% 46% 30% 8%	760
	11th to 20th	Night	6% 2 10% 39% 33% 9%	760
	21st to end	Night	6% 2 12% 39% 26% 15%	836
November	1st to 10th	Night	12% 2 10% 38% 28% 11%	780
	11th to 20th	Night	11% 2 16% 40% 23% 8%	800
	21st to end	Night	14% 2 13% 39% 24% 8%	800
December	1st to 10th	Night	18% 3 13% 37% 23% 7%	800
	11th to 20th	Night	25% 3 12% 36% 20% 5%	800
	21st to end	Night	22% 3 19% 33% 19% 4	880

Page generated at 2025-05-23 06:21:00. Version ac07

Copyright © 2025 Attilla Danko.