Killarney
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Killarney clear sky chart from 2005-11-06 to 2026-07-01.

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	14% 10% 3 8% 5% 4 4 4 5% 7% 36%	137769
	Night	14% 11% 4 9% 5% 5% 4 4 5% 6% 32%	134729
Transparency	Day	32% 36% 8% 16% 8% 1	141270
	Night	34% 36% 7% 15% 8% 1	139316
Seeing	Day	22% 13% 33% 22% 8% 2	17423
	Night	22% 11% 28% 27% 10% 1	26628

By Month

Percentage Cloud Cover NE (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	13% 19% 7% 11% 4 4 4 3 4 4 27%	4094
	11th to 20th	Day	9% 16% 8% 18% 8% 6% 4 3 5% 5% 17%	4559
	21st to end	Day	10% 16% 7% 13% 7% 6% 5% 4 5% 6% 23%	5534
February	1st to 10th	Day	11% 16% 5% 10% 7% 5% 5% 4 5% 6% 27%	1890
	11th to 20th	Day	12% 14% 4 10% 6% 5% 5% 4 5% 5% 30%	1843
	21st to end	Day	12% 16% 5% 11% 5% 5% 5% 4 4 6% 27%	1681
March	1st to 10th	Day	17% 12% 3 8% 4 4 4 3 5% 6% 32%	4828
	11th to 20th	Day	13% 12% 4 10% 5% 6% 5% 4 6% 8% 28%	5090
	21st to end	Day	16% 12% 4 9% 4 4 3 3 4 5% 34%	5586
April	1st to 10th	Day	17% 10% 4 7% 5% 4 4 3 5% 7% 32%	2466
	11th to 20th	Day	19% 8% 2 6% 4 3 4 4 5% 5% 38%	2702
	21st to end	Day	20% 8% 3 6% 4 3 3 3 5% 7% 37%	2730
May	1st to 10th	Day	15% 6% 2 6% 4 4 4 4 6% 7% 41%	7642
	11th to 20th	Day	15% 7% 3 6% 4 4 5% 4 5% 8% 38%	8079
	21st to end	Day	16% 7% 3 6% 4 4 4 3 5% 6% 42%	9316
June	1st to 10th	Day	14% 6% 2 7% 5% 4 5% 4 7% 7% 39%	3150
	11th to 20th	Day	12% 6% 2 6% 5% 4 5% 4 6% 8% 43%	3150
	21st to end	Day	15% 7% 2 7% 5% 5% 4 3 6% 8% 38%	3150
July	1st to 10th	Day	13% 7% 3 7% 5% 4 5% 4 6% 8% 40%	6820
	11th to 20th	Day	9% 4 2 6% 4 3 4 4 6% 8% 50%	6820
	21st to end	Day	8% 5% 2 5% 3 3 4 3 6% 9% 51%	6668
August	1st to 10th	Day	9% 6% 2 6% 4 4 4 4 7% 9% 43%	4234
	11th to 20th	Day	15% 6% 2 4 3 3 4 4 6% 9% 44%	4174
	21st to end	Day	9% 5% 2 6% 4 4 5% 4 6% 9% 45%	4675
September	1st to 10th	Day	11% 6% 3 7% 5% 4 4 4 6% 8% 42%	2383
	11th to 20th	Day	11% 5% 1 5% 4 5% 4 5% 7% 8% 46%	2200
	21st to end	Day	18% 7% 2 7% 5% 4 3 3 5% 7% 39%	2200
October	1st to 10th	Day	16% 7% 2 6% 5% 4 5% 3 6% 7% 39%	2035
	11th to 20th	Day	23% 10% 3 7% 5% 5% 5% 4 5% 6% 27%	2000
	21st to end	Day	24% 12% 3 8% 5% 4 4 3 5% 5% 26%	2065
November	1st to 10th	Day	19% 10% 3 9% 5% 5% 5% 3 6% 6% 29%	1777
	11th to 20th	Day	15% 14% 5% 9% 5% 6% 6% 4 6% 6% 24%	1680
	21st to end	Day	21% 18% 6% 11% 6% 4 5% 3 4 5% 18%	1680
December	1st to 10th	Day	14% 20% 5% 11% 6% 5% 5% 4 6% 7% 18%	2624
	11th to 20th	Day	18% 16% 7% 11% 5% 5% 4 4 5% 5% 20%	2691
	21st to end	Day	27% 21% 5% 9% 4 5% 4 3 3 4 16%	3553
January	1st to 10th	Night	11% 14% 7% 12% 6% 5% 5% 4 6% 6% 24%	8831
	11th to 20th	Night	11% 19% 6% 13% 6% 5% 5% 4 5% 6% 21%	8338
	21st to end	Night	9% 16% 7% 14% 6% 6% 5% 4 6% 6% 22%	8659
February	1st to 10th	Night	12% 13% 5% 12% 5% 5% 5% 4 5% 6% 28%	2730
	11th to 20th	Night	10% 14% 5% 10% 7% 6% 6% 4 6% 5% 29%	2663
	21st to end	Night	13% 16% 4 11% 6% 5% 5% 4 5% 5% 27%	2123
March	1st to 10th	Night	16% 10% 3 8% 4 4 4 3 4 6% 36%	5231
	11th to 20th	Night	12% 11% 4 9% 5% 5% 5% 5% 6% 8% 31%	5089
	21st to end	Night	18% 11% 5% 10% 4 4 3 3 3 5% 34%	5588
April	1st to 10th	Night	19% 10% 3 7% 4 4 5% 4 5% 5% 34%	2170
	11th to 20th	Night	19% 8% 3 6% 5% 3 4 3 5% 6% 39%	1867
	21st to end	Night	19% 10% 3 9% 5% 4 4 3 4 6% 33%	1890
May	1st to 10th	Night	14% 7% 3 7% 5% 4 5% 3 6% 8% 39%	5257
	11th to 20th	Night	14% 7% 3 7% 4 4 4 3 6% 8% 40%	4781
	21st to end	Night	15% 8% 3 6% 4 4 3 3 5% 6% 43%	4855
June	1st to 10th	Night	12% 8% 2 5% 5% 4 5% 4 8% 7% 40%	1470
	11th to 20th	Night	10% 5% 2 6% 5% 5% 5% 4 6% 9% 42%	1470
	21st to end	Night	13% 6% 3 7% 5% 4 4 5% 6% 9% 40%	1470
July	1st to 10th	Night	13% 7% 2 6% 4 4 4 3 5% 7% 45%	3160
	11th to 20th	Night	10% 4 2 4 4 3 4 3 5% 8% 51%	3160
	21st to end	Night	9% 5% 2 5% 4 4 4 4 6% 8% 50%	4190
August	1st to 10th	Night	9% 7% 3 6% 4 4 5% 4 6% 9% 43%	2915
	11th to 20th	Night	14% 6% 2 5% 4 4 4 3 5% 7% 45%	2875
	21st to end	Night	9% 6% 2 5% 4 4 4 4 5% 7% 50%	3223
September	1st to 10th	Night	11% 6% 3 6% 4 3 5% 3 5% 7% 47%	1992
	11th to 20th	Night	11% 5% 2 4 3 4 3 4 5% 8% 51%	2200
	21st to end	Night	16% 7% 2 6% 4 4 4 3 5% 7% 41%	2200
October	1st to 10th	Night	18% 8% 2 6% 4 4 4 3 5% 7% 38%	2364
	11th to 20th	Night	23% 9% 3 7% 4 5% 5% 4 5% 6% 28%	2400
	21st to end	Night	23% 11% 3 9% 5% 5% 4 3 5% 6% 27%	2770
November	1st to 10th	Night	18% 12% 2 8% 4 4 4 4 6% 6% 31%	2740
	11th to 20th	Night	17% 13% 5% 10% 6% 5% 5% 3 5% 6% 25%	2940
	21st to end	Night	21% 16% 5% 10% 6% 5% 4 4 5% 5% 20%	2940
December	1st to 10th	Night	16% 18% 4 10% 6% 5% 5% 4 5% 5% 21%	4775
	11th to 20th	Night	16% 14% 6% 14% 6% 5% 4 3 5% 5% 20%	5736
	21st to end	Night	25% 18% 6% 11% 6% 4 4 2 4 4 16%	7667

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	47% 23% 6% 16% 5% 2	4095
	11th to 20th	Day	57% 23% 5% 8% 5% 1	4590
	21st to end	Day	48% 24% 5% 12% 10%	5534
February	1st to 10th	Day	25% 59% 4 9% 3	1890
	11th to 20th	Day	25% 58% 4 8% 5%	1852
	21st to end	Day	26% 59% 2 9% 4	1681
March	1st to 10th	Day	41% 30% 7% 6% 13% 3	4831
	11th to 20th	Day	41% 30% 10% 10% 7% 1	5090
	21st to end	Day	39% 30% 9% 11% 9% 2	5586
April	1st to 10th	Day	22% 58% 4 10% 5%	2466
	11th to 20th	Day	21% 59% 2 11% 6% 1	2702
	21st to end	Day	20% 59% 4 10% 5% 1	2730
May	1st to 10th	Day	32% 25% 9% 21% 10% 3	7651
	11th to 20th	Day	34% 25% 9% 18% 12% 2	8083
	21st to end	Day	35% 24% 6% 20% 12% 3	9317
June	1st to 10th	Day	17% 59% 4 11% 8% 1	3150
	11th to 20th	Day	18% 59% 4 11% 7% 1	3150
	21st to end	Day	20% 57% 5% 11% 6% 1	3150
July	1st to 10th	Day	33% 27% 12% 20% 7%	6747
	11th to 20th	Day	23% 27% 11% 33% 6%	6739
	21st to end	Day	21% 27% 11% 27% 13%	6477
August	1st to 10th	Day	22% 38% 10% 22% 7% 1	4221
	11th to 20th	Day	27% 38% 10% 17% 8%	4213
	21st to end	Day	22% 37% 10% 24% 7%	4674
September	1st to 10th	Day	19% 58% 7% 11% 4	2383
	11th to 20th	Day	12% 57% 6% 17% 8%	2200
	21st to end	Day	18% 57% 7% 12% 5%	2200
October	1st to 10th	Day	23% 36% 6% 22% 13%	3308
	11th to 20th	Day	25% 37% 11% 22% 5%	3240
	21st to end	Day	38% 36% 8% 13% 5%	3315
November	1st to 10th	Day	29% 53% 5% 9% 4	1777
	11th to 20th	Day	28% 54% 6% 8% 4	1680
	21st to end	Day	29% 55% 5% 8% 3	1680
December	1st to 10th	Day	41% 37% 13% 7% 2	2624
	11th to 20th	Day	46% 32% 5% 9% 8% 1	2691
	21st to end	Day	56% 26% 4 9% 5%	3553
January	1st to 10th	Night	45% 25% 7% 15% 7% 1	8831
	11th to 20th	Night	51% 24% 8% 9% 9%	8382
	21st to end	Night	48% 25% 6% 11% 9% 1	8659
February	1st to 10th	Night	23% 59% 3 10% 4	2730
	11th to 20th	Night	23% 58% 4 9% 5%	2665
	21st to end	Night	25% 60% 2 8% 5%	2123
March	1st to 10th	Night	36% 30% 6% 12% 11% 4	5241
	11th to 20th	Night	37% 31% 11% 14% 6% 1	5090
	21st to end	Night	41% 29% 4 13% 12% 2	5588
April	1st to 10th	Night	24% 59% 3 9% 6%	2170
	11th to 20th	Night	19% 59% 3 9% 8% 1	1867
	21st to end	Night	22% 59% 4 9% 6% 1	1890
May	1st to 10th	Night	33% 24% 6% 22% 12% 3	5264
	11th to 20th	Night	33% 24% 7% 20% 13% 2	4782
	21st to end	Night	35% 23% 4 23% 11% 3	4856
June	1st to 10th	Night	15% 59% 3 12% 8% 3	1470
	11th to 20th	Night	16% 59% 5% 11% 8% 1	1470
	21st to end	Night	16% 57% 5% 12% 8% 1	1470
July	1st to 10th	Night	31% 27% 9% 21% 9% 1	3125
	11th to 20th	Night	23% 27% 10% 32% 8%	3118
	21st to end	Night	23% 26% 8% 28% 14%	4067
August	1st to 10th	Night	23% 38% 10% 19% 10%	2904
	11th to 20th	Night	25% 38% 14% 16% 7%	2902
	21st to end	Night	19% 38% 9% 25% 9%	3223
September	1st to 10th	Night	16% 58% 8% 14% 5%	1992
	11th to 20th	Night	12% 57% 7% 17% 8%	2200
	21st to end	Night	17% 58% 6% 12% 7%	2200
October	1st to 10th	Night	22% 36% 6% 24% 13%	3871
	11th to 20th	Night	23% 37% 11% 23% 7%	3899
	21st to end	Night	30% 37% 14% 13% 5%	4470
November	1st to 10th	Night	26% 54% 6% 9% 4	2740
	11th to 20th	Night	26% 55% 6% 9% 4	2940
	21st to end	Night	29% 56% 4 6% 5%	2940
December	1st to 10th	Night	41% 36% 10% 10% 3	4775
	11th to 20th	Night	43% 32% 5% 8% 10% 1	5735
	21st to end	Night	53% 27% 5% 9% 6%	7667

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	23% 16% 33% 21% 6%	220
	11th to 20th	Day	23% 15% 36% 19% 6%	308
	21st to end	Day	25% 13% 33% 21% 7% 1	363
February	1st to 10th	Day	27% 22% 31% 14% 6%	330
	11th to 20th	Day	26% 20% 38% 12% 3 1	330
	21st to end	Day	32% 22% 35% 10%	273
March	1st to 10th	Day	27% 21% 32% 16% 4	438
	11th to 20th	Day	26% 14% 35% 19% 6% 1	540
	21st to end	Day	28% 15% 34% 17% 5% 1	594
April	1st to 10th	Day	27% 15% 30% 21% 7% 1	540
	11th to 20th	Day	31% 16% 26% 16% 8% 3	532
	21st to end	Day	32% 14% 30% 15% 8% 1	540
May	1st to 10th	Day	22% 15% 34% 20% 6% 2	543
	11th to 20th	Day	21% 12% 34% 19% 13% 2	567
	21st to end	Day	19% 10% 35% 23% 10% 2	704
June	1st to 10th	Day	17% 12% 35% 28% 7% 1	780
	11th to 20th	Day	18% 13% 37% 24% 8% 1	780
	21st to end	Day	21% 11% 33% 25% 8% 2	780
July	1st to 10th	Day	11% 10% 36% 31% 11% 2	722
	11th to 20th	Day	12% 10% 35% 28% 10% 4	718
	21st to end	Day	12% 7% 36% 29% 13% 4	683
August	1st to 10th	Day	15% 6% 30% 30% 13% 5%	526
	11th to 20th	Day	12% 4 32% 29% 13% 9%	519
	21st to end	Day	15% 9% 30% 26% 14% 6%	583
September	1st to 10th	Day	15% 9% 32% 25% 12% 6%	530
	11th to 20th	Day	14% 5% 27% 31% 15% 7%	530
	21st to end	Day	23% 10% 25% 27% 12% 2	530
October	1st to 10th	Day	22% 12% 30% 22% 10% 3	530
	11th to 20th	Day	28% 13% 37% 17% 4 1	530
	21st to end	Day	33% 15% 33% 17% 2 1	448
November	1st to 10th	Day	33% 17% 34% 12% 5%	290
	11th to 20th	Day	25% 22% 35% 15% 3	220
	21st to end	Day	31% 23% 28% 13% 5%	220
December	1st to 10th	Day	29% 13% 35% 16% 7%	220
	11th to 20th	Day	32% 20% 33% 14% 1	220
	21st to end	Day	38% 15% 32% 10% 4	242
January	1st to 10th	Night	23% 13% 32% 24% 7% 1	1050
	11th to 20th	Night	26% 16% 28% 23% 7%	1050
	21st to end	Night	20% 9% 31% 29% 8% 1	1013
February	1st to 10th	Night	21% 14% 35% 25% 5%	840
	11th to 20th	Night	20% 15% 33% 25% 6% 1	823
	21st to end	Night	21% 17% 34% 23% 5%	692
March	1st to 10th	Night	19% 17% 35% 23% 6%	840
	11th to 20th	Night	21% 13% 35% 22% 8% 1	840
	21st to end	Night	22% 11% 31% 28% 7% 1	924
April	1st to 10th	Night	25% 12% 32% 26% 5%	799
	11th to 20th	Night	25% 12% 26% 25% 11% 1	623
	21st to end	Night	25% 10% 27% 27% 11%	630
May	1st to 10th	Night	16% 7% 27% 36% 13% 1	630
	11th to 20th	Night	15% 8% 29% 34% 13% 1	467
	21st to end	Night	16% 7% 28% 33% 14% 2	455
June	1st to 10th	Night	18% 6% 28% 36% 12%	420
	11th to 20th	Night	14% 7% 25% 40% 14% 1	420
	21st to end	Night	16% 4 25% 36% 16% 2	420
July	1st to 10th	Night	11% 4 23% 47% 14% 1	390
	11th to 20th	Night	9% 3 21% 45% 21% 1	388
	21st to end	Night	10% 4 22% 40% 21% 2	647
August	1st to 10th	Night	12% 3 22% 38% 23% 2	597
	11th to 20th	Night	14% 3 23% 33% 24% 4	594
	21st to end	Night	15% 5% 23% 29% 25% 3	660
September	1st to 10th	Night	17% 6% 27% 30% 18% 3	762
	11th to 20th	Night	14% 6% 25% 29% 22% 6%	800
	21st to end	Night	20% 7% 26% 27% 17% 3	800
October	1st to 10th	Night	24% 8% 25% 28% 13% 2	800
	11th to 20th	Night	30% 12% 27% 23% 6% 2	800
	21st to end	Night	30% 14% 28% 24% 4 1	880
November	1st to 10th	Night	27% 15% 28% 24% 7%	820
	11th to 20th	Night	26% 18% 28% 22% 6%	840
	21st to end	Night	32% 17% 29% 18% 4 1	840
December	1st to 10th	Night	26% 17% 31% 19% 7%	869
	11th to 20th	Night	27% 17% 34% 17% 4 1	1050
	21st to end	Night	33% 14% 27% 19% 6%	1155

Page generated at 2026-06-28 02:10:45. Version ac07

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