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 2024-09-29.

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% 9% 3 8% 5% 4 4 4 5% 7% 36%	101240
	Night	15% 11% 4 8% 5% 4 4 4 5% 6% 33%	97064
Transparency	Day	25% 49% 6% 13% 6% 1	100991
	Night	27% 50% 6% 11% 6% 1	96932
Seeing	Day	21% 12% 33% 23% 9% 2	15168
	Night	22% 11% 28% 27% 11% 1	24325

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	17% 20% 10% 11% 4 4 3 2 3 4 21%	2208
	11th to 20th	Day	10% 13% 7% 18% 9% 6% 5% 3 6% 5% 17%	2466
	21st to end	Day	16% 19% 7% 12% 7% 5% 5% 4 5% 4 17%	2982
February	1st to 10th	Day	11% 15% 5% 10% 7% 5% 5% 4 5% 6% 26%	1710
	11th to 20th	Day	12% 14% 4 10% 6% 6% 5% 3 5% 5% 31%	1663
	21st to end	Day	13% 15% 5% 11% 5% 5% 5% 3 3 6% 28%	1525
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% 4 4 3 3 5% 7% 38%	2069
October	1st to 10th	Day	17% 7% 2 7% 5% 4 5% 4 6% 7% 36%	1832
	11th to 20th	Day	24% 11% 3 7% 5% 4 5% 4 5% 6% 25%	1800
	21st to end	Day	25% 12% 3 8% 5% 4 4 3 5% 5% 25%	1859
November	1st to 10th	Day	18% 10% 3 9% 5% 5% 5% 3 6% 6% 29%	1605
	11th to 20th	Day	15% 14% 5% 10% 6% 5% 6% 4 6% 6% 24%	1520
	21st to end	Day	22% 18% 6% 10% 6% 3 4 3 4 5% 18%	1520
December	1st to 10th	Day	14% 21% 5% 11% 6% 4 5% 3 5% 6% 20%	1492
	11th to 20th	Day	19% 15% 6% 8% 5% 6% 4 5% 6% 5% 22%	1671
	21st to end	Day	26% 22% 5% 10% 5% 4 3 3 4 4 15%	2431
January	1st to 10th	Night	14% 16% 7% 11% 5% 6% 5% 4 6% 6% 20%	4748
	11th to 20th	Night	13% 14% 5% 13% 6% 6% 5% 4 5% 6% 22%	4500
	21st to end	Night	15% 19% 7% 12% 6% 5% 4 4 4 4 20%	4678
February	1st to 10th	Night	12% 13% 5% 12% 6% 5% 5% 4 5% 6% 27%	2470
	11th to 20th	Night	11% 13% 4 9% 7% 5% 6% 4 5% 5% 30%	2403
	21st to end	Night	13% 15% 4 11% 5% 5% 5% 4 5% 6% 27%	1927
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% 3 6% 4 4 4 3 5% 7% 41%	2079
October	1st to 10th	Night	19% 9% 2 7% 5% 4 4 3 5% 7% 36%	2127
	11th to 20th	Night	24% 10% 3 7% 4 5% 4 4 5% 6% 28%	2160
	21st to end	Night	25% 12% 3 9% 6% 5% 4 3 5% 5% 25%	2492
November	1st to 10th	Night	18% 12% 2 7% 4 4 4 4 6% 7% 31%	2472
	11th to 20th	Night	17% 13% 5% 9% 7% 5% 5% 3 5% 6% 24%	2660
	21st to end	Night	21% 16% 5% 9% 6% 5% 4 4 5% 5% 20%	2660
December	1st to 10th	Night	17% 19% 5% 9% 6% 5% 5% 4 5% 5% 19%	2685
	11th to 20th	Night	18% 16% 5% 10% 6% 4 4 4 5% 6% 23%	3526
	21st to end	Night	25% 20% 6% 11% 6% 4 3 2 3 5% 15%	5236

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% 39% 7% 6% 3	2209
	11th to 20th	Day	47% 41% 6% 5% 2 1	2466
	21st to end	Day	44% 43% 5% 5% 3	2982
February	1st to 10th	Day	21% 65% 4 8% 2	1710
	11th to 20th	Day	20% 63% 3 8% 5%	1672
	21st to end	Day	22% 64% 2 7% 5%	1525
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% 8% 11% 4	2069
October	1st to 10th	Day	20% 63% 4 8% 5%	1832
	11th to 20th	Day	22% 63% 5% 7% 3	1800
	21st to end	Day	24% 61% 4 7% 4 1	1859
November	1st to 10th	Day	26% 58% 4 8% 4	1605
	11th to 20th	Day	25% 60% 5% 7% 4	1520
	21st to end	Day	25% 60% 4 7% 3	1520
December	1st to 10th	Day	26% 60% 5% 6% 3	1492
	11th to 20th	Day	32% 49% 5% 9% 4 1	1671
	21st to end	Day	50% 37% 4 6% 3	2431
January	1st to 10th	Night	39% 43% 6% 7% 5%	4748
	11th to 20th	Night	38% 41% 10% 8% 2	4500
	21st to end	Night	44% 42% 4 7% 2	4678
February	1st to 10th	Night	20% 65% 3 9% 3	2470
	11th to 20th	Night	19% 64% 3 9% 5%	2405
	21st to end	Night	20% 65% 2 6% 5%	1927
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% 5%	2079
October	1st to 10th	Night	21% 63% 4 8% 5%	2127
	11th to 20th	Night	20% 63% 5% 9% 3	2160
	21st to end	Night	24% 61% 4 7% 4	2492
November	1st to 10th	Night	23% 59% 6% 8% 4	2472
	11th to 20th	Night	24% 60% 5% 7% 4	2660
	21st to end	Night	26% 61% 4 5% 5%	2660
December	1st to 10th	Night	27% 60% 3 7% 3	2685
	11th to 20th	Night	30% 50% 5% 7% 6% 1	3525
	21st to end	Night	48% 37% 5% 5% 4	5236

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% 18% 29% 21% 7% 1	180
	11th to 20th	Day	22% 13% 36% 21% 8%	252
	21st to end	Day	28% 11% 33% 20% 8% 1	297
February	1st to 10th	Day	27% 22% 32% 14% 5%	270
	11th to 20th	Day	23% 21% 39% 14% 2 1	270
	21st to end	Day	35% 23% 33% 9%	225
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% 25% 25% 13% 2	483
October	1st to 10th	Day	22% 12% 28% 23% 11% 3	450
	11th to 20th	Day	30% 13% 34% 18% 5% 1	450
	21st to end	Day	34% 14% 33% 16% 2 1	374
November	1st to 10th	Day	31% 16% 37% 12% 5%	238
	11th to 20th	Day	25% 22% 33% 17% 3 1	180
	21st to end	Day	32% 21% 27% 14% 6%	180
December	1st to 10th	Day	30% 11% 36% 17% 6% 1	180
	11th to 20th	Day	31% 19% 33% 15% 1 1	180
	21st to end	Day	36% 16% 34% 10% 4 1	198
January	1st to 10th	Night	25% 13% 30% 24% 7% 1	950
	11th to 20th	Night	26% 15% 27% 24% 8% 1	950
	21st to end	Night	21% 9% 29% 30% 9% 2	917
February	1st to 10th	Night	21% 14% 35% 26% 5%	760
	11th to 20th	Night	20% 15% 34% 25% 7% 1	743
	21st to end	Night	21% 17% 34% 23% 5%	628
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% 8% 25% 26% 17% 3	756
October	1st to 10th	Night	26% 8% 24% 28% 13% 2	720
	11th to 20th	Night	31% 12% 26% 23% 7% 2	720
	21st to end	Night	32% 14% 26% 23% 4 1	792
November	1st to 10th	Night	26% 14% 26% 25% 8%	740
	11th to 20th	Night	27% 17% 28% 22% 7%	760
	21st to end	Night	31% 16% 28% 19% 5% 1	760
December	1st to 10th	Night	27% 16% 31% 19% 6%	785
	11th to 20th	Night	28% 16% 33% 18% 5% 1	950
	21st to end	Night	33% 14% 27% 20% 6%	1045

Page generated at 2024-09-26 09:52:20. Version ac07

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