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 2024-11-02.

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 2 2 4 5% 66%	101134
	Night	11% 4 1 3 2 2 3 2 4 5% 62%	98018
Transparency	Day	23% 2 6% 18% 24% 27%	100885
	Night	27% 2 7% 20% 22% 23%	97856
Seeing	Day	9% 9% 25% 34% 18% 5%	15217
	Night	11% 3 12% 38% 29% 7%	24580

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	22% 7% 2 5% 3 4 3 2 4 5% 44%	2539
	11th to 20th	Day	21% 9% 2 8% 5% 5% 4 3 4 5% 35%	2769
	21st to end	Day	21% 8% 2 7% 5% 4 4 4 6% 7% 31%	3146
February	1st to 10th	Day	20% 6% 2 4 3 2 3 4 3 5% 48%	1710
	11th to 20th	Day	14% 7% 2 5% 4 3 4 3 4 7% 47%	1841
	21st to end	Day	19% 6% 1 5% 4 3 4 3 4 5% 45%	1570
March	1st to 10th	Day	16% 11% 3 8% 5% 5% 5% 5% 7% 6% 30%	3183
	11th to 20th	Day	13% 5% 1 3 2 2 3 3 5% 6% 57%	3490
	21st to end	Day	15% 8% 3 6% 4 5% 5% 4 6% 8% 37%	4010
April	1st to 10th	Day	13% 5% 2 4 3 3 4 3 5% 7% 51%	2280
	11th to 20th	Day	11% 4 2 4 3 3 3 2 5% 7% 57%	2249
	21st to end	Day	8% 4 1 3 2 2 3 3 4 5% 64%	2280
May	1st to 10th	Day	6% 3 1 2 2 2 2 2 3 5% 72%	3848
	11th to 20th	Day	3 2 1 2 2 1 2 2 3 5% 79%	4305
	21st to end	Day	4 2 1 2 1 2 2 2 3 5% 77%	4813
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	4 3 1 2 2 2 2 2 3 6% 73%	1900
	11th to 20th	Day	4 2 1 3 2 2 2 3 4 4 73%	1900
	21st to end	Day	7% 2 1 2 2 3 2 3 4 5% 69%	2090
November	1st to 10th	Day	9% 5% 2 4 3 3 4 3 5% 7% 55%	1704
	11th to 20th	Day	10% 4 1 4 3 3 3 4 4 6% 59%	1710
	21st to end	Day	12% 4 1 4 2 3 3 2 5% 6% 57%	1659
December	1st to 10th	Day	15% 4 2 5% 3 4 3 2 4 6% 51%	1520
	11th to 20th	Day	28% 8% 2 5% 3 3 3 2 4 5% 34%	1928
	21st to end	Day	14% 7% 3 6% 4 4 5% 4 7% 9% 37%	2794
January	1st to 10th	Night	17% 8% 2 5% 3 3 3 3 4 6% 45%	4406
	11th to 20th	Night	21% 8% 3 6% 4 5% 4 3 5% 6% 35%	4194
	21st to end	Night	23% 8% 2 5% 5% 4 4 4 5% 5% 35%	4521
February	1st to 10th	Night	16% 7% 1 5% 4 2 3 2 4 5% 50%	2470
	11th to 20th	Night	17% 5% 1 3 3 3 3 3 5% 7% 50%	2224
	21st to end	Night	18% 8% 1 4 3 3 3 2 4 5% 50%	1884
March	1st to 10th	Night	21% 10% 2 6% 4 4 4 3 5% 5% 36%	3688
	11th to 20th	Night	16% 4 1 4 2 2 2 2 3 5% 58%	3490
	21st to end	Night	23% 8% 2 5% 3 3 4 3 5% 6% 39%	3629
April	1st to 10th	Night	13% 4 2 5% 3 3 4 4 5% 7% 51%	1900
	11th to 20th	Night	11% 4 1 4 3 2 4 3 4 6% 59%	1879
	21st to end	Night	7% 4 1 3 3 2 3 3 4 6% 64%	1900
May	1st to 10th	Night	4 5% 1 2 1 1 2 2 3 5% 74%	3128
	11th to 20th	Night	3 1 2 1 1 1 2 3 5% 80%	2586
	21st to end	Night	2 2 1 2 1 2 1 2 3 4 80%	2762
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	5% 2 1 2 2 2 2 2 4 4 73%	2280
	11th to 20th	Night	5% 2 1 2 2 2 2 2 3 4 76%	2280
	21st to end	Night	5% 2 2 1 2 2 2 4 6% 73%	2508
November	1st to 10th	Night	12% 4 1 3 2 2 2 2 4 7% 61%	2394
	11th to 20th	Night	10% 3 1 4 3 3 2 3 5% 6% 60%	2470
	21st to end	Night	11% 5% 1 4 3 3 3 2 4 6% 58%	2517
December	1st to 10th	Night	16% 5% 1 5% 3 2 4 2 4 6% 51%	2660
	11th to 20th	Night	28% 7% 2 5% 4 3 3 3 5% 5% 37%	3276
	21st to end	Night	17% 7% 3 7% 5% 4 5% 4 5% 7% 35%	4862

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	44% 1 10% 26% 15% 3	2539
	11th to 20th	Day	54% 1 9% 16% 12% 8%	2769
	21st to end	Day	52% 2 10% 20% 12% 3	3146
February	1st to 10th	Day	40% 1 8% 24% 17% 9%	1710
	11th to 20th	Day	38% 2 8% 21% 25% 6%	1851
	21st to end	Day	42% 3 8% 24% 19% 4	1570
March	1st to 10th	Day	53% 2 12% 17% 13% 2	3183
	11th to 20th	Day	30% 2 11% 34% 13% 10%	3490
	21st to end	Day	46% 2 12% 26% 11% 2	4010
April	1st to 10th	Day	34% 3 12% 26% 17% 8%	2280
	11th to 20th	Day	29% 2 12% 30% 20% 7%	2252
	21st to end	Day	25% 2 9% 32% 27% 5%	2280
May	1st to 10th	Day	18% 2 6% 30% 28% 16%	3848
	11th to 20th	Day	11% 1 4 25% 44% 14%	4308
	21st to end	Day	14% 2 6% 28% 42% 8%	4814
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	16% 1 5% 16% 27% 35%	1900
	11th to 20th	Day	17% 2 5% 21% 27% 29%	1900
	21st to end	Day	20% 2 5% 21% 30% 23%	2090
November	1st to 10th	Day	30% 2 8% 24% 23% 14%	1704
	11th to 20th	Day	27% 2 10% 22% 27% 11%	1710
	21st to end	Day	30% 2 7% 22% 27% 12%	1659
December	1st to 10th	Day	36% 2 9% 22% 19% 12%	1520
	11th to 20th	Day	54% 2 7% 16% 15% 7%	1928
	21st to end	Day	45% 1 14% 24% 10% 5%	2794
January	1st to 10th	Night	41% 1 15% 25% 14% 3	4406
	11th to 20th	Night	50% 2 12% 16% 11% 9%	4194
	21st to end	Night	52% 1 9% 20% 12% 6%	4521
February	1st to 10th	Night	39% 2 7% 21% 21% 10%	2470
	11th to 20th	Night	35% 2 9% 26% 19% 9%	2225
	21st to end	Night	39% 2 10% 24% 19% 5%	1884
March	1st to 10th	Night	51% 2 10% 20% 12% 5%	3688
	11th to 20th	Night	31% 2 8% 31% 16% 11%	3490
	21st to end	Night	48% 2 10% 26% 10% 4	3629
April	1st to 10th	Night	33% 4 14% 23% 19% 7%	1900
	11th to 20th	Night	28% 4 12% 27% 20% 9%	1879
	21st to end	Night	23% 4 11% 33% 23% 7%	1900
May	1st to 10th	Night	16% 2 10% 29% 28% 16%	3128
	11th to 20th	Night	10% 1 7% 28% 38% 15%	2586
	21st to end	Night	12% 1 7% 37% 36% 7%	2762
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	16% 2 5% 17% 26% 34%	2280
	11th to 20th	Night	14% 2 5% 20% 29% 30%	2280
	21st to end	Night	15% 1 5% 22% 32% 25%	2508
November	1st to 10th	Night	26% 2 9% 24% 20% 20%	2394
	11th to 20th	Night	26% 2 8% 24% 27% 13%	2470
	21st to end	Night	30% 3 6% 21% 28% 12%	2517
December	1st to 10th	Night	36% 2 9% 22% 19% 13%	2660
	11th to 20th	Night	51% 2 8% 15% 17% 7%	3276
	21st to end	Night	49% 2 12% 22% 10% 5%	4862

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	30% 13% 19% 22% 13% 2	180
	11th to 20th	Day	20% 6% 20% 29% 18% 6%	318
	21st to end	Day	20% 7% 20% 28% 22% 4	407
February	1st to 10th	Day	23% 12% 18% 24% 18% 5%	370
	11th to 20th	Day	20% 10% 29% 26% 13% 2	451
	21st to end	Day	18% 13% 26% 30% 12% 1	382
March	1st to 10th	Day	23% 13% 27% 26% 10% 1	460
	11th to 20th	Day	20% 14% 28% 19% 15% 3	460
	21st to end	Day	19% 15% 29% 26% 10% 1	506
April	1st to 10th	Day	16% 15% 33% 22% 12% 2	460
	11th to 20th	Day	15% 17% 28% 27% 10% 3	452
	21st to end	Day	8% 15% 31% 29% 13% 4	460
May	1st to 10th	Day	8% 19% 27% 30% 11% 5%	463
	11th to 20th	Day	8% 13% 30% 31% 13% 5%	488
	21st to end	Day	7% 12% 25% 33% 16% 7%	529
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% 9% 16% 29% 29% 7%	294
	11th to 20th	Day	9% 6% 20% 33% 24% 7%	270
	21st to end	Day	12% 5% 23% 30% 26% 4	246
December	1st to 10th	Day	17% 7% 22% 29% 16% 8%	180
	11th to 20th	Day	19% 8% 24% 25% 17% 6%	180
	21st to end	Day	22% 11% 21% 24% 16% 6%	198
January	1st to 10th	Night	21% 3 16% 32% 19% 9%	760
	11th to 20th	Night	16% 4 12% 36% 25% 7%	760
	21st to end	Night	21% 4 12% 33% 22% 8%	836
February	1st to 10th	Night	19% 3 15% 37% 19% 6%	760
	11th to 20th	Night	18% 5% 15% 33% 21% 8%	744
	21st to end	Night	21% 5% 14% 40% 15% 4	628
March	1st to 10th	Night	23% 6% 15% 32% 19% 4	760
	11th to 20th	Night	19% 5% 16% 30% 24% 6%	760
	21st to end	Night	19% 6% 18% 34% 20% 3	836
April	1st to 10th	Night	14% 4 15% 43% 22% 3	760
	11th to 20th	Night	10% 7% 17% 38% 21% 6%	751
	21st to end	Night	8% 3 16% 41% 25% 6%	760
May	1st to 10th	Night	7% 4 19% 41% 23% 6%	734
	11th to 20th	Night	5% 3 14% 41% 35% 2	418
	21st to end	Night	4 2 13% 39% 39% 2	411
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 9% 38% 28% 11%	744
	11th to 20th	Night	11% 2 14% 40% 24% 9%	760
	21st to end	Night	13% 2 13% 39% 25% 9%	760
December	1st to 10th	Night	19% 3 13% 37% 21% 7%	760
	11th to 20th	Night	25% 3 12% 35% 20% 6%	760
	21st to end	Night	22% 3 18% 33% 20% 4	836

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