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 2025-02-25.

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% 35%	108349
	Night	15% 12% 4 9% 5% 5% 4 4 5% 6% 32%	110422
Transparency	Day	28% 44% 7% 14% 7% 1	111894
	Night	30% 42% 7% 13% 7% 1	115040
Seeing	Day	22% 12% 33% 22% 9% 2	15573
	Night	22% 11% 28% 27% 11% 1	24967

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% 17% 7% 9% 4 4 4 3 4 4 31%	3158
	11th to 20th	Day	9% 14% 7% 17% 9% 7% 5% 4 6% 5% 18%	3497
	21st to end	Day	13% 19% 7% 13% 7% 5% 5% 4 5% 5% 18%	4272
February	1st to 10th	Day	11% 15% 5% 10% 7% 5% 5% 4 5% 6% 27%	1800
	11th to 20th	Day	11% 14% 4 10% 6% 6% 5% 3 5% 5% 31%	1753
	21st to end	Day	13% 15% 5% 11% 6% 5% 5% 3 3 6% 28%	1563
March	1st to 10th	Day	16% 13% 4 8% 4 4 4 3 5% 7% 31%	3293
	11th to 20th	Day	9% 13% 4 11% 6% 6% 5% 3 5% 7% 31%	3480
	21st to end	Day	13% 11% 4 9% 5% 4 4 4 5% 5% 37%	3815
April	1st to 10th	Day	18% 10% 4 8% 6% 4 4 3 5% 7% 31%	2230
	11th to 20th	Day	19% 9% 2 6% 4 3 5% 4 5% 5% 37%	2442
	21st to end	Day	21% 8% 3 6% 4 3 3 3 5% 7% 37%	2470
May	1st to 10th	Day	17% 6% 2 6% 4 4 4 3 6% 7% 40%	4108
	11th to 20th	Day	13% 7% 3 7% 4 5% 6% 4 6% 8% 39%	4324
	21st to end	Day	15% 6% 2 6% 4 4 5% 4 5% 6% 44%	4981
June	1st to 10th	Day	15% 6% 2 7% 5% 4 5% 4 7% 7% 39%	2850
	11th to 20th	Day	12% 6% 2 6% 5% 3 5% 4 6% 8% 43%	2850
	21st to end	Day	15% 7% 2 7% 5% 4 4 3 6% 8% 39%	2850
July	1st to 10th	Day	14% 7% 3 7% 5% 4 5% 4 6% 8% 39%	4760
	11th to 20th	Day	9% 4 2 5% 4 4 5% 4 6% 9% 49%	4760
	21st to end	Day	10% 5% 2 5% 3 3 4 3 5% 8% 52%	4640
August	1st to 10th	Day	9% 6% 2 6% 4 4 4 4 7% 9% 43%	4104
	11th to 20th	Day	15% 6% 2 4 3 3 4 4 7% 9% 44%	4044
	21st to end	Day	9% 5% 2 6% 3 4 5% 4 6% 9% 45%	4532
September	1st to 10th	Day	11% 6% 3 7% 4 4 4 4 6% 8% 43%	2264
	11th to 20th	Day	12% 5% 1 5% 4 5% 4 4 6% 8% 45%	2090
	21st to end	Day	18% 7% 2 7% 5% 4 3 3 5% 7% 39%	2090
October	1st to 10th	Day	17% 7% 2 6% 5% 4 5% 4 6% 7% 38%	1933
	11th to 20th	Day	23% 10% 3 7% 5% 5% 5% 4 5% 6% 26%	1900
	21st to end	Day	25% 12% 3 8% 5% 4 4 3 5% 5% 25%	1962
November	1st to 10th	Day	18% 10% 3 9% 5% 5% 5% 3 6% 6% 29%	1691
	11th to 20th	Day	15% 14% 5% 10% 6% 5% 6% 4 6% 6% 24%	1600
	21st to end	Day	21% 18% 6% 11% 6% 3 5% 3 4 5% 17%	1600
December	1st to 10th	Day	14% 20% 5% 11% 6% 5% 5% 4 6% 7% 18%	2546
	11th to 20th	Day	18% 16% 7% 11% 6% 5% 4 4 5% 5% 20%	2621
	21st to end	Day	27% 21% 5% 9% 4 5% 4 3 3 4 15%	3476
January	1st to 10th	Night	10% 14% 6% 10% 5% 5% 5% 4 6% 7% 27%	6808
	11th to 20th	Night	12% 16% 5% 12% 6% 5% 5% 4 5% 6% 23%	6390
	21st to end	Night	12% 18% 7% 13% 5% 6% 5% 4 5% 5% 20%	6692
February	1st to 10th	Night	12% 13% 5% 13% 6% 5% 5% 4 5% 6% 27%	2600
	11th to 20th	Night	11% 13% 5% 10% 7% 6% 6% 4 6% 5% 29%	2533
	21st to end	Night	13% 15% 4 11% 6% 5% 5% 4 5% 6% 26%	1984
March	1st to 10th	Night	15% 10% 3 8% 4 4 4 3 5% 6% 38%	3546
	11th to 20th	Night	9% 11% 5% 9% 6% 4 4 4 5% 7% 37%	3479
	21st to end	Night	13% 9% 6% 9% 5% 4 4 3 4 6% 38%	3817
April	1st to 10th	Night	20% 10% 3 7% 5% 4 4 4 4 5% 34%	1964
	11th to 20th	Night	19% 8% 3 5% 5% 3 3 2 5% 6% 39%	1687
	21st to end	Night	19% 10% 3 9% 5% 3 4 3 4 5% 33%	1710
May	1st to 10th	Night	16% 6% 3 8% 5% 5% 5% 3 5% 6% 39%	2833
	11th to 20th	Night	10% 7% 3 8% 4 5% 5% 4 8% 10% 37%	2569
	21st to end	Night	13% 8% 3 8% 4 4 4 3 5% 8% 42%	2596
June	1st to 10th	Night	12% 8% 2 5% 5% 5% 5% 4 8% 7% 38%	1330
	11th to 20th	Night	10% 5% 2 5% 5% 5% 5% 4 6% 9% 43%	1330
	21st to end	Night	13% 6% 3 6% 4 3 4 4 6% 8% 41%	1330
July	1st to 10th	Night	13% 7% 2 6% 4 3 4 3 5% 7% 46%	2210
	11th to 20th	Night	11% 4 2 5% 5% 3 4 3 6% 9% 49%	2210
	21st to end	Night	9% 5% 2 5% 4 4 4 4 5% 7% 51%	2914
August	1st to 10th	Night	9% 7% 3 6% 4 4 5% 5% 6% 8% 43%	2825
	11th to 20th	Night	14% 6% 2 5% 4 4 4 3 5% 7% 45%	2785
	21st to end	Night	9% 6% 2 5% 4 4 4 4 5% 7% 50%	3124
September	1st to 10th	Night	12% 6% 3 6% 4 3 4 3 4 7% 47%	1892
	11th to 20th	Night	12% 5% 2 4 3 4 4 4 5% 8% 50%	2090
	21st to end	Night	17% 7% 2 6% 4 4 4 3 5% 7% 41%	2090
October	1st to 10th	Night	19% 8% 2 7% 4 4 4 3 4 7% 37%	2246
	11th to 20th	Night	23% 10% 3 7% 4 5% 5% 4 5% 6% 28%	2280
	21st to end	Night	24% 11% 3 9% 5% 5% 4 3 5% 6% 25%	2631
November	1st to 10th	Night	19% 12% 2 7% 4 4 4 3 6% 7% 31%	2606
	11th to 20th	Night	18% 13% 5% 9% 7% 5% 5% 3 5% 6% 24%	2800
	21st to end	Night	21% 16% 5% 9% 6% 5% 4 4 5% 5% 19%	2800
December	1st to 10th	Night	16% 18% 4 9% 6% 5% 5% 4 5% 5% 21%	4633
	11th to 20th	Night	17% 15% 6% 14% 6% 5% 4 3 5% 5% 19%	5586
	21st to end	Night	25% 18% 6% 11% 6% 4 4 2 4 4 16%	7502

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	40% 29% 7% 16% 5% 2	3159
	11th to 20th	Day	51% 30% 6% 8% 5% 1	3528
	21st to end	Day	49% 31% 4 9% 6%	4272
February	1st to 10th	Day	23% 62% 4 9% 3	1800
	11th to 20th	Day	22% 60% 4 8% 5%	1762
	21st to end	Day	23% 63% 2 8% 5%	1563
March	1st to 10th	Day	34% 42% 8% 6% 8% 1	3296
	11th to 20th	Day	33% 42% 7% 13% 4 1	3480
	21st to end	Day	31% 42% 8% 10% 8% 2	3815
April	1st to 10th	Day	19% 64% 3 9% 5%	2230
	11th to 20th	Day	19% 65% 2 10% 4 1	2442
	21st to end	Day	18% 65% 3 8% 5% 1	2470
May	1st to 10th	Day	26% 43% 7% 17% 7% 1	4120
	11th to 20th	Day	24% 42% 8% 18% 6% 1	4328
	21st to end	Day	26% 41% 6% 10% 14% 2	4981
June	1st to 10th	Day	15% 65% 3 9% 6% 1	2850
	11th to 20th	Day	15% 64% 4 9% 7% 1	2850
	21st to end	Day	17% 63% 4 10% 6% 1	2850
July	1st to 10th	Day	31% 37% 11% 14% 6% 1	4686
	11th to 20th	Day	20% 37% 11% 26% 6%	4679
	21st to end	Day	19% 36% 7% 24% 14%	4492
August	1st to 10th	Day	22% 39% 9% 22% 7% 1	4091
	11th to 20th	Day	27% 39% 10% 17% 8%	4083
	21st to end	Day	22% 38% 9% 24% 7%	4531
September	1st to 10th	Day	17% 60% 7% 11% 4	2264
	11th to 20th	Day	12% 60% 6% 15% 8%	2090
	21st to end	Day	17% 60% 7% 11% 4	2090
October	1st to 10th	Day	22% 37% 6% 22% 13%	3206
	11th to 20th	Day	24% 38% 11% 22% 5%	3140
	21st to end	Day	38% 37% 8% 12% 5%	3212
November	1st to 10th	Day	28% 55% 5% 9% 4	1691
	11th to 20th	Day	27% 57% 5% 8% 4	1600
	21st to end	Day	27% 58% 4 8% 3	1600
December	1st to 10th	Day	41% 38% 13% 7% 2	2546
	11th to 20th	Day	45% 32% 5% 9% 8% 1	2621
	21st to end	Day	56% 27% 4 8% 5%	3476
January	1st to 10th	Night	38% 31% 8% 15% 7% 1	6808
	11th to 20th	Night	44% 30% 9% 9% 8%	6434
	21st to end	Night	48% 31% 5% 8% 7% 1	6692
February	1st to 10th	Night	21% 62% 3 10% 4	2600
	11th to 20th	Night	21% 61% 4 9% 5%	2535
	21st to end	Night	22% 64% 2 6% 5%	1984
March	1st to 10th	Night	28% 43% 6% 13% 9% 1	3556
	11th to 20th	Night	27% 43% 7% 15% 6% 2	3480
	21st to end	Night	30% 41% 4 14% 10% 2	3817
April	1st to 10th	Night	21% 64% 2 7% 5%	1964
	11th to 20th	Night	17% 65% 2 8% 7% 1	1687
	21st to end	Night	19% 64% 4 7% 5% 1	1710
May	1st to 10th	Night	29% 41% 5% 17% 8%	2840
	11th to 20th	Night	25% 41% 6% 16% 11% 1	2570
	21st to end	Night	28% 40% 6% 15% 7% 4	2597
June	1st to 10th	Night	14% 65% 2 11% 7% 2	1330
	11th to 20th	Night	13% 65% 4 9% 8% 1	1330
	21st to end	Night	14% 63% 4 11% 8% 1	1330
July	1st to 10th	Night	27% 37% 9% 15% 9% 2	2175
	11th to 20th	Night	21% 36% 10% 27% 6%	2168
	21st to end	Night	19% 36% 6% 22% 17%	2822
August	1st to 10th	Night	23% 39% 10% 18% 10%	2814
	11th to 20th	Night	25% 39% 14% 16% 6%	2812
	21st to end	Night	19% 39% 8% 24% 9%	3124
September	1st to 10th	Night	15% 60% 7% 13% 5%	1892
	11th to 20th	Night	11% 60% 6% 15% 8%	2090
	21st to end	Night	16% 61% 6% 12% 6%	2090
October	1st to 10th	Night	22% 37% 5% 23% 12%	3753
	11th to 20th	Night	22% 38% 11% 23% 6%	3779
	21st to end	Night	30% 38% 14% 12% 5%	4331
November	1st to 10th	Night	24% 57% 6% 9% 4	2606
	11th to 20th	Night	25% 57% 5% 8% 4	2800
	21st to end	Night	28% 58% 4 5% 5%	2800
December	1st to 10th	Night	41% 37% 10% 9% 3	4633
	11th to 20th	Night	43% 33% 5% 8% 10% 1	5585
	21st to end	Night	53% 27% 5% 9% 6%	7502

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	24% 16% 32% 22% 7% 1	200
	11th to 20th	Day	21% 14% 38% 20% 7%	280
	21st to end	Day	26% 13% 33% 19% 8% 1	330
February	1st to 10th	Day	28% 23% 31% 13% 5%	300
	11th to 20th	Day	24% 21% 40% 12% 2 1	300
	21st to end	Day	34% 23% 33% 10%	237
March	1st to 10th	Day	25% 20% 32% 18% 4 1	368
	11th to 20th	Day	24% 12% 36% 21% 6% 1	460
	21st to end	Day	26% 14% 35% 19% 6% 1	506
April	1st to 10th	Day	25% 13% 31% 22% 8% 1	460
	11th to 20th	Day	31% 16% 25% 17% 8% 3	452
	21st to end	Day	32% 14% 29% 15% 9% 1	460
May	1st to 10th	Day	21% 12% 37% 21% 7% 3	463
	11th to 20th	Day	21% 11% 33% 20% 13% 2	487
	21st to end	Day	18% 9% 35% 25% 11% 2	608
June	1st to 10th	Day	18% 12% 35% 27% 7% 1	680
	11th to 20th	Day	17% 12% 36% 25% 8% 2	680
	21st to end	Day	21% 10% 32% 26% 9% 2	680
July	1st to 10th	Day	10% 10% 35% 31% 11% 2	671
	11th to 20th	Day	12% 10% 34% 29% 11% 4	668
	21st to end	Day	13% 6% 34% 30% 13% 4	634
August	1st to 10th	Day	16% 6% 29% 30% 14% 6%	486
	11th to 20th	Day	13% 4 30% 29% 14% 10%	479
	21st to end	Day	16% 9% 29% 26% 14% 6%	539
September	1st to 10th	Day	15% 8% 33% 26% 12% 5%	490
	11th to 20th	Day	15% 6% 28% 32% 14% 6%	490
	21st to end	Day	24% 11% 24% 26% 13% 2	490
October	1st to 10th	Day	23% 13% 29% 22% 10% 3	490
	11th to 20th	Day	28% 13% 35% 18% 5% 1	490
	21st to end	Day	35% 14% 33% 15% 2 1	411
November	1st to 10th	Day	31% 17% 36% 11% 5%	264
	11th to 20th	Day	26% 23% 33% 16% 3 1	200
	21st to end	Day	29% 24% 28% 14% 6%	200
December	1st to 10th	Day	29% 12% 36% 16% 7% 1	200
	11th to 20th	Day	31% 20% 35% 14% 1 1	200
	21st to end	Day	37% 15% 33% 10% 5%	220
January	1st to 10th	Night	24% 13% 32% 24% 7% 1	1000
	11th to 20th	Night	25% 15% 28% 24% 8% 1	1000
	21st to end	Night	21% 10% 30% 29% 9% 2	965
February	1st to 10th	Night	21% 14% 36% 25% 5%	800
	11th to 20th	Night	20% 15% 34% 24% 7% 1	783
	21st to end	Night	21% 17% 34% 22% 5%	647
March	1st to 10th	Night	19% 17% 34% 24% 6%	760
	11th to 20th	Night	20% 13% 35% 23% 9% 1	760
	21st to end	Night	20% 11% 31% 29% 8% 1	836
April	1st to 10th	Night	24% 10% 33% 27% 6%	723
	11th to 20th	Night	25% 12% 26% 25% 11% 2	563
	21st to end	Night	25% 10% 26% 27% 12%	570
May	1st to 10th	Night	16% 6% 26% 36% 14% 1	570
	11th to 20th	Night	14% 8% 29% 34% 14% 1	422
	21st to end	Night	15% 6% 28% 34% 15% 2	411
June	1st to 10th	Night	19% 5% 27% 37% 12% 1	380
	11th to 20th	Night	14% 7% 23% 41% 14% 1	380
	21st to end	Night	17% 4 24% 36% 17% 2	380
July	1st to 10th	Night	11% 4 23% 46% 15% 1	370
	11th to 20th	Night	8% 4 21% 45% 21% 1	368
	21st to end	Night	10% 4 21% 40% 21% 2	614
August	1st to 10th	Night	13% 3 22% 36% 24% 2	567
	11th to 20th	Night	13% 2 22% 33% 25% 4	564
	21st to end	Night	15% 6% 22% 29% 26% 3	627
September	1st to 10th	Night	16% 5% 26% 31% 18% 3	724
	11th to 20th	Night	14% 6% 25% 29% 21% 6%	760
	21st to end	Night	21% 7% 25% 27% 16% 3	760
October	1st to 10th	Night	25% 8% 25% 28% 12% 2	760
	11th to 20th	Night	30% 12% 27% 23% 6% 2	760
	21st to end	Night	31% 15% 27% 23% 4 1	836
November	1st to 10th	Night	27% 14% 27% 24% 7%	780
	11th to 20th	Night	27% 17% 27% 23% 6%	800
	21st to end	Night	31% 16% 29% 18% 5% 1	800
December	1st to 10th	Night	27% 16% 31% 19% 7%	827
	11th to 20th	Night	27% 17% 33% 17% 5% 1	1000
	21st to end	Night	33% 14% 27% 20% 6%	1100

Page generated at 2025-02-22 06:51:38. Version ac07

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