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 2024-03-06.

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	9% 4 1 3 3 2 3 3 4 5% 63%	78644
	Night	12% 4 2 3 3 2 3 3 4 6% 59%	80900
Transparency	Day	26% 2 7% 19% 24% 22%	78358
	Night	29% 2 8% 20% 22% 19%	80707
Seeing	Day	10% 9% 25% 34% 18% 5%	14254
	Night	11% 3 12% 38% 29% 7%	23781

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 4 4 3 3 3 4 5% 44%	2539
	11th to 20th	Day	21% 8% 3 7% 6% 4 4 4 4 5% 35%	2769
	21st to end	Day	21% 8% 2 6% 6% 3 4 5% 5% 8% 31%	3146
February	1st to 10th	Day	20% 6% 2 4 3 2 3 4 4 5% 48%	1710
	11th to 20th	Day	15% 6% 3 5% 4 3 3 4 5% 7% 47%	1841
	21st to end	Day	19% 6% 2 4 5% 2 4 4 4 6% 45%	1570
March	1st to 10th	Day	19% 9% 2 5% 5% 3 4 5% 5% 6% 37%	1870
	11th to 20th	Day	18% 6% 2 4 4 2 5% 5% 6% 7% 41%	1980
	21st to end	Day	14% 6% 2 4 4 3 4 5% 4 7% 45%	2286
April	1st to 10th	Day	14% 5% 2 3 4 3 4 4 5% 7% 50%	2160
	11th to 20th	Day	11% 3 2 4 3 2 3 3 5% 7% 57%	2129
	21st to end	Day	9% 3 2 3 3 2 3 3 4 5% 63%	2160
May	1st to 10th	Day	6% 4 1 3 3 2 3 3 4 6% 65%	2182
	11th to 20th	Day	5% 3 1 3 3 2 2 3 4 6% 68%	2431
	21st to end	Day	7% 3 1 3 3 2 3 4 5% 6% 64%	2723
June	1st to 10th	Day	4 3 1 3 3 2 2 3 4 7% 69%	2520
	11th to 20th	Day	1 1 1 1 2 1 2 2 3 4 83%	2520
	21st to end	Day	2 2 1 1 1 2 2 2 3 84%	2520
July	1st to 10th	Day	1 1 1 1 2 2 3 88%	2520
	11th to 20th	Day	1 1 1 1 1 1 2 2 2 4 83%	2520
	21st to end	Day	1 1 1 1 2 1 2 2 3 4 82%	2568
August	1st to 10th	Day	2 1 1 2 1 1 1 2 2 3 84%	2309
	11th to 20th	Day	1 1 1 1 1 2 3 4 85%	2122
	21st to end	Day	1 1 1 1 1 1 1 1 2 2 88%	2376
September	1st to 10th	Day	2 1 1 1 1 1 1 2 2 89%	2160
	11th to 20th	Day	2 1 1 2 1 2 2 2 3 5% 79%	2156
	21st to end	Day	3 1 1 2 2 1 2 2 3 4 80%	1972
October	1st to 10th	Day	5% 2 1 2 3 1 2 2 3 6% 73%	1800
	11th to 20th	Day	5% 2 1 3 2 1 2 4 4 4 72%	1800
	21st to end	Day	7% 2 1 2 2 2 2 3 4 5% 69%	1980
November	1st to 10th	Day	10% 4 2 3 3 3 4 3 5% 6% 56%	1694
	11th to 20th	Day	10% 3 2 3 4 2 3 5% 4 6% 59%	1710
	21st to end	Day	12% 4 2 3 3 3 3 3 5% 6% 57%	1659
December	1st to 10th	Day	15% 4 2 4 4 3 4 3 4 6% 51%	1520
	11th to 20th	Day	29% 7% 3 5% 4 2 4 3 4 5% 34%	1928
	21st to end	Day	14% 7% 3 5% 5% 3 5% 5% 6% 9% 37%	2794
January	1st to 10th	Night	17% 8% 2 4 4 2 3 4 4 7% 46%	4406
	11th to 20th	Night	21% 7% 3 5% 5% 3 4 4 5% 6% 35%	4194
	21st to end	Night	23% 7% 2 4 6% 3 4 5% 5% 6% 35%	4521
February	1st to 10th	Night	17% 6% 2 4 4 2 3 2 4 5% 50%	2470
	11th to 20th	Night	17% 5% 1 3 4 2 3 4 5% 7% 50%	2224
	21st to end	Night	18% 7% 1 4 3 3 3 2 4 5% 50%	1884
March	1st to 10th	Night	22% 8% 3 4 5% 2 3 4 4 5% 41%	2203
	11th to 20th	Night	20% 4 1 4 3 3 4 4 4 7% 45%	1980
	21st to end	Night	18% 5% 2 3 4 3 4 3 4 6% 49%	2069
April	1st to 10th	Night	13% 4 2 4 4 2 4 5% 4 7% 51%	1800
	11th to 20th	Night	11% 4 1 3 3 1 4 4 4 6% 59%	1779
	21st to end	Night	7% 4 1 3 3 2 3 4 4 7% 63%	1800
May	1st to 10th	Night	6% 3 1 3 2 1 2 3 4 6% 68%	1776
	11th to 20th	Night	6% 2 1 2 2 1 2 2 4 7% 70%	1458
	21st to end	Night	5% 2 1 3 2 1 3 3 4 6% 69%	1552
June	1st to 10th	Night	4 2 1 2 2 1 2 3 3 7% 73%	1440
	11th to 20th	Night	1 1 1 1 2 2 4 4 85%	1440
	21st to end	Night	1 1 1 2 1 1 1 2 3 3 85%	1440
July	1st to 10th	Night	1 1 1 1 2 2 3 89%	1440
	11th to 20th	Night	2 1 1 1 1 2 2 2 3 3 83%	1440
	21st to end	Night	1 2 1 2 2 2 3 2 3 4 78%	1745
August	1st to 10th	Night	2 2 1 1 1 1 2 3 3 82%	1628
	11th to 20th	Night	1 1 1 1 2 1 2 3 4 5% 80%	1780
	21st to end	Night	2 1 1 1 1 2 1 3 87%	1980
September	1st to 10th	Night	1 1 1 1 1 1 2 1 2 90%	1800
	11th to 20th	Night	2 2 1 1 1 1 1 2 3 4 82%	1802
	21st to end	Night	2 2 1 1 2 1 1 1 2 4 83%	1986
October	1st to 10th	Night	5% 2 1 2 2 1 3 3 4 4 73%	2160
	11th to 20th	Night	5% 2 1 2 2 2 2 3 3 4 75%	2160
	21st to end	Night	5% 2 2 2 1 2 2 3 6% 74%	2376
November	1st to 10th	Night	12% 3 1 3 2 2 2 3 4 7% 61%	2382
	11th to 20th	Night	10% 3 1 3 3 2 3 3 5% 6% 60%	2470
	21st to end	Night	11% 4 1 3 3 2 3 3 4 6% 58%	2517
December	1st to 10th	Night	16% 5% 1 5% 4 2 4 3 4 6% 51%	2660
	11th to 20th	Night	28% 6% 2 5% 4 2 3 3 5% 6% 37%	3276
	21st to end	Night	17% 6% 3 6% 6% 3 5% 5% 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	49% 3 9% 19% 17% 3	1870
	11th to 20th	Day	43% 3 8% 26% 17% 4	1980
	21st to end	Day	39% 4 14% 24% 14% 4	2286
April	1st to 10th	Day	35% 3 12% 24% 17% 8%	2160
	11th to 20th	Day	29% 2 11% 29% 20% 8%	2132
	21st to end	Day	25% 2 9% 32% 27% 5%	2160
May	1st to 10th	Day	22% 2 9% 26% 31% 10%	2182
	11th to 20th	Day	20% 2 7% 27% 34% 11%	2434
	21st to end	Day	23% 3 10% 29% 27% 8%	2724
June	1st to 10th	Day	18% 3 7% 22% 31% 18%	2520
	11th to 20th	Day	9% 1 5% 21% 34% 30%	2520
	21st to end	Day	10% 1 1 9% 32% 46%	2520
July	1st to 10th	Day	5% 1 1 7% 22% 63%	2451
	11th to 20th	Day	9% 1 2 8% 24% 55%	2445
	21st to end	Day	9% 1 1 7% 25% 57%	2425
August	1st to 10th	Day	10% 1 1 9% 26% 54%	2293
	11th to 20th	Day	6% 2 8% 30% 54%	2122
	21st to end	Day	6% 1 7% 36% 50%	2376
September	1st to 10th	Day	6% 1 1 6% 28% 57%	2160
	11th to 20th	Day	11% 2 2 21% 39% 26%	2156
	21st to end	Day	12% 1 2 18% 38% 30%	1972
October	1st to 10th	Day	17% 1 5% 17% 28% 32%	1800
	11th to 20th	Day	17% 2 5% 22% 25% 30%	1800
	21st to end	Day	20% 2 5% 21% 29% 24%	1980
November	1st to 10th	Day	30% 2 7% 23% 23% 14%	1694
	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	47% 3 9% 19% 17% 5%	2203
	11th to 20th	Night	40% 3 9% 22% 19% 7%	1980
	21st to end	Night	37% 3 12% 25% 16% 7%	2069
April	1st to 10th	Night	33% 4 15% 22% 19% 7%	1800
	11th to 20th	Night	28% 4 12% 26% 20% 9%	1779
	21st to end	Night	23% 4 11% 32% 23% 7%	1800
May	1st to 10th	Night	20% 2 11% 24% 32% 10%	1776
	11th to 20th	Night	16% 2 11% 31% 29% 11%	1458
	21st to end	Night	18% 3 12% 32% 27% 8%	1552
June	1st to 10th	Night	15% 3 12% 25% 31% 15%	1440
	11th to 20th	Night	6% 2 6% 24% 33% 29%	1440
	21st to end	Night	9% 1 1 13% 31% 45%	1440
July	1st to 10th	Night	4 1 1 8% 25% 62%	1400
	11th to 20th	Night	8% 2 2 8% 23% 57%	1392
	21st to end	Night	14% 2 1 6% 23% 55%	1648
August	1st to 10th	Night	10% 2 1 11% 26% 52%	1619
	11th to 20th	Night	9% 2 10% 27% 52%	1780
	21st to end	Night	7% 1 8% 30% 54%	1980
September	1st to 10th	Night	5% 1 2 7% 28% 57%	1800
	11th to 20th	Night	10% 1 2 17% 41% 28%	1802
	21st to end	Night	9% 2 2 16% 41% 30%	1986
October	1st to 10th	Night	16% 2 5% 18% 27% 31%	2160
	11th to 20th	Night	15% 2 5% 20% 27% 31%	2160
	21st to end	Night	15% 1 5% 23% 31% 26%	2376
November	1st to 10th	Night	26% 2 8% 24% 20% 20%	2382
	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	24% 13% 27% 25% 10% 1	441
	11th to 20th	Day	21% 15% 28% 18% 15% 3	420
	21st to end	Day	19% 15% 28% 27% 11% 1	462
April	1st to 10th	Day	16% 15% 34% 22% 11% 2	420
	11th to 20th	Day	16% 18% 29% 26% 9% 3	412
	21st to end	Day	8% 15% 30% 28% 14% 4	420
May	1st to 10th	Day	9% 18% 26% 31% 11% 5%	423
	11th to 20th	Day	9% 14% 31% 30% 12% 5%	448
	21st to end	Day	8% 13% 24% 33% 15% 6%	485
June	1st to 10th	Day	4 12% 28% 35% 13% 8%	450
	11th to 20th	Day	2 12% 31% 37% 14% 5%	450
	21st to end	Day	2 6% 28% 38% 18% 8%	450
July	1st to 10th	Day	1 2 26% 45% 17% 8%	446
	11th to 20th	Day	1 1 20% 47% 22% 9%	444
	21st to end	Day	1 1 20% 49% 21% 8%	487
August	1st to 10th	Day	3 3 21% 48% 18% 7%	447
	11th to 20th	Day	2 3 25% 43% 20% 8%	437
	21st to end	Day	1 3 22% 47% 21% 6%	495
September	1st to 10th	Day	3 3 23% 44% 24% 5%	450
	11th to 20th	Day	4 5% 28% 38% 21% 4	450
	21st to end	Day	4 6% 23% 40% 24% 2	450
October	1st to 10th	Day	4 11% 25% 33% 23% 4	450
	11th to 20th	Day	7% 7% 21% 33% 27% 6%	450
	21st to end	Day	7% 8% 23% 32% 24% 5%	495
November	1st to 10th	Day	11% 9% 16% 28% 29% 7%	290
	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	24% 6% 15% 31% 20% 4	742
	11th to 20th	Night	19% 4 15% 30% 25% 7%	720
	21st to end	Night	18% 6% 18% 34% 21% 3	792
April	1st to 10th	Night	14% 4 14% 42% 23% 3	720
	11th to 20th	Night	10% 7% 18% 38% 21% 6%	711
	21st to end	Night	8% 4 16% 41% 25% 7%	720
May	1st to 10th	Night	7% 4 17% 42% 24% 6%	696
	11th to 20th	Night	6% 3 14% 40% 35% 3	396
	21st to end	Night	5% 2 14% 38% 39% 2	389
June	1st to 10th	Night	5% 1 12% 38% 39% 4	360
	11th to 20th	Night	1 12% 45% 38% 4	360
	21st to end	Night	2 1 9% 45% 41% 4	360
July	1st to 10th	Night	2 44% 51% 3	350
	11th to 20th	Night	1 1 3 43% 46% 5%	348
	21st to end	Night	1 1 4 36% 48% 10%	563
August	1st to 10th	Night	3 4 37% 47% 9%	554
	11th to 20th	Night	1 1 7% 43% 39% 10%	712
	21st to end	Night	2 4 43% 44% 7%	792
September	1st to 10th	Night	1 1 5% 40% 44% 9%	720
	11th to 20th	Night	3 1 8% 41% 37% 10%	720
	21st to end	Night	3 1 9% 39% 37% 12%	720
October	1st to 10th	Night	5% 2 9% 46% 30% 8%	720
	11th to 20th	Night	6% 2 10% 40% 33% 9%	720
	21st to end	Night	6% 2 12% 38% 27% 16%	792
November	1st to 10th	Night	12% 2 9% 38% 28% 11%	740
	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

Page generated at 2024-03-03 03:28:53. Version ac07

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