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 2024-02-05.

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	15% 9% 4 7% 6% 3 5% 5% 5% 7% 35%	77896
	Night	16% 11% 4 8% 6% 3 5% 5% 5% 6% 31%	80983
Transparency	Day	33% 37% 9% 13% 7% 1	77597
	Night	37% 36% 9% 12% 6% 1	80817
Seeing	Day	22% 12% 32% 23% 9% 3	14188
	Night	22% 11% 28% 27% 11% 1	23591

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	18% 19% 10% 10% 5% 4 3 3 3 4 21%	2208
	11th to 20th	Day	10% 13% 8% 15% 11% 4 6% 4 6% 5% 17%	2466
	21st to end	Day	17% 18% 7% 10% 9% 4 5% 5% 5% 5% 17%	2982
February	1st to 10th	Day	12% 14% 6% 9% 8% 4 6% 5% 5% 6% 27%	1656
	11th to 20th	Day	13% 12% 4 9% 7% 3 6% 4 5% 6% 31%	1573
	21st to end	Day	13% 15% 5% 11% 6% 4 5% 4 3 6% 28%	1438
March	1st to 10th	Day	12% 11% 4 6% 5% 3 4 4 5% 8% 36%	1889
	11th to 20th	Day	12% 10% 4 8% 6% 3 4 5% 5% 5% 38%	1980
	21st to end	Day	15% 9% 3 5% 6% 3 4 4 5% 6% 39%	2178
April	1st to 10th	Day	18% 9% 4 7% 6% 3 4 5% 5% 7% 31%	2112
	11th to 20th	Day	18% 8% 3 6% 5% 2 5% 5% 5% 6% 38%	2312
	21st to end	Day	21% 7% 3 5% 5% 2 3 3 5% 7% 37%	2340
May	1st to 10th	Day	16% 8% 2 6% 5% 3 4 4 6% 7% 39%	2340
	11th to 20th	Day	16% 6% 3 5% 4 3 5% 5% 5% 8% 40%	2432
	21st to end	Day	13% 5% 3 4 5% 3 5% 5% 6% 8% 44%	2799
June	1st to 10th	Day	15% 5% 2 5% 6% 3 4 5% 7% 7% 40%	2700
	11th to 20th	Day	12% 5% 2 5% 6% 2 6% 5% 6% 8% 43%	2700
	21st to end	Day	14% 6% 3 6% 5% 3 4 4 5% 9% 40%	2700
July	1st to 10th	Day	8% 4 2 5% 5% 3 4 5% 7% 9% 49%	2700
	11th to 20th	Day	9% 4 2 5% 6% 3 6% 6% 7% 8% 44%	2700
	21st to end	Day	10% 5% 2 5% 4 2 5% 5% 6% 9% 47%	2651
August	1st to 10th	Day	11% 6% 2 4 4 3 4 4 6% 9% 46%	2327
	11th to 20th	Day	11% 5% 2 4 5% 3 4 5% 6% 9% 45%	2303
	21st to end	Day	10% 6% 3 5% 4 3 5% 5% 6% 9% 44%	2574
September	1st to 10th	Day	12% 6% 3 6% 5% 3 3 5% 6% 8% 43%	2146
	11th to 20th	Day	12% 5% 1 4 5% 4 4 5% 6% 8% 45%	1980
	21st to end	Day	18% 6% 3 6% 6% 3 4 4 5% 7% 38%	1980
October	1st to 10th	Day	17% 7% 2 5% 6% 3 5% 4 6% 7% 36%	1832
	11th to 20th	Day	24% 10% 4 6% 7% 4 4 6% 5% 6% 25%	1800
	21st to end	Day	25% 12% 3 7% 6% 3 4 5% 5% 5% 25%	1859
November	1st to 10th	Day	18% 10% 3 7% 7% 4 5% 5% 5% 7% 29%	1605
	11th to 20th	Day	16% 12% 6% 8% 7% 4 5% 6% 6% 6% 24%	1520
	21st to end	Day	23% 17% 7% 9% 7% 2 5% 4 4 5% 18%	1520
December	1st to 10th	Day	14% 18% 7% 10% 6% 4 4 4 5% 6% 20%	1492
	11th to 20th	Day	20% 13% 6% 8% 5% 4 5% 5% 6% 5% 22%	1671
	21st to end	Day	26% 22% 5% 9% 6% 3 4 3 4 4 15%	2431
January	1st to 10th	Night	15% 15% 7% 10% 7% 4 6% 5% 6% 6% 20%	4748
	11th to 20th	Night	13% 13% 5% 12% 8% 4 6% 6% 5% 6% 22%	4500
	21st to end	Night	15% 18% 7% 11% 7% 4 4 5% 4 4 20%	4678
February	1st to 10th	Night	12% 13% 5% 11% 7% 4 6% 5% 5% 7% 26%	2399
	11th to 20th	Night	12% 12% 5% 9% 7% 4 6% 5% 5% 5% 30%	2273
	21st to end	Night	14% 14% 5% 10% 7% 4 5% 4 5% 6% 27%	1816
March	1st to 10th	Night	12% 10% 4 8% 5% 3 4 5% 5% 6% 39%	2057
	11th to 20th	Night	14% 9% 4 6% 6% 4 5% 5% 4 6% 37%	1979
	21st to end	Night	16% 8% 3 6% 6% 3 4 4 4 7% 39%	2178
April	1st to 10th	Night	20% 9% 3 6% 5% 3 4 5% 4 5% 34%	1861
	11th to 20th	Night	19% 8% 3 5% 5% 2 4 3 5% 6% 41%	1597
	21st to end	Night	19% 10% 3 8% 6% 3 4 4 5% 6% 33%	1620
May	1st to 10th	Night	13% 7% 3 6% 6% 4 5% 5% 6% 7% 37%	1620
	11th to 20th	Night	13% 7% 2 5% 5% 3 5% 5% 6% 9% 40%	1461
	21st to end	Night	11% 7% 3 5% 4 3 5% 4 6% 8% 45%	1473
June	1st to 10th	Night	12% 7% 2 4 6% 4 5% 5% 8% 7% 40%	1260
	11th to 20th	Night	11% 5% 2 4 6% 3 6% 5% 6% 10% 43%	1260
	21st to end	Night	13% 6% 4 6% 5% 3 4 5% 6% 9% 41%	1260
July	1st to 10th	Night	9% 4 2 4 4 2 4 4 6% 7% 54%	1260
	11th to 20th	Night	7% 4 2 5% 6% 3 5% 5% 6% 9% 47%	1260
	21st to end	Night	9% 5% 2 5% 6% 3 5% 6% 6% 8% 46%	1663
August	1st to 10th	Night	9% 5% 3 4 5% 3 5% 6% 7% 8% 46%	1611
	11th to 20th	Night	11% 5% 3 5% 5% 4 4 5% 5% 7% 47%	1598
	21st to end	Night	12% 6% 3 5% 5% 3 4 5% 5% 7% 44%	1782
September	1st to 10th	Night	12% 5% 3 5% 5% 3 4 4 5% 7% 47%	1791
	11th to 20th	Night	13% 5% 2 4 4 3 4 5% 5% 8% 48%	1980
	21st to end	Night	17% 7% 3 5% 5% 3 4 4 5% 7% 40%	1980
October	1st to 10th	Night	19% 8% 2 6% 6% 3 4 4 4 7% 36%	2127
	11th to 20th	Night	24% 9% 3 6% 5% 4 4 5% 5% 6% 28%	2160
	21st to end	Night	25% 11% 3 8% 6% 4 4 4 5% 6% 25%	2492
November	1st to 10th	Night	18% 12% 3 6% 6% 3 4 4 6% 7% 31%	2472
	11th to 20th	Night	18% 12% 6% 9% 7% 3 6% 4 5% 6% 24%	2660
	21st to end	Night	22% 15% 5% 8% 7% 4 4 5% 5% 6% 20%	2660
December	1st to 10th	Night	18% 17% 6% 8% 7% 4 6% 5% 5% 5% 19%	2685
	11th to 20th	Night	18% 15% 6% 9% 7% 3 4 5% 5% 6% 23%	3526
	21st to end	Night	25% 19% 6% 10% 7% 3 4 3 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	53% 27% 11% 7% 1	2209
	11th to 20th	Day	55% 30% 8% 5% 2	2466
	21st to end	Day	57% 26% 8% 6% 3	2982
February	1st to 10th	Day	39% 38% 9% 9% 5% 1	1656
	11th to 20th	Day	37% 38% 7% 10% 6% 1	1582
	21st to end	Day	39% 38% 6% 12% 5%	1438
March	1st to 10th	Day	32% 38% 11% 10% 9% 1	1892
	11th to 20th	Day	33% 37% 7% 15% 7% 1	1980
	21st to end	Day	31% 38% 9% 13% 8% 2	2178
April	1st to 10th	Day	35% 38% 8% 11% 7% 1	2112
	11th to 20th	Day	30% 37% 7% 16% 10%	2312
	21st to end	Day	31% 37% 7% 13% 10% 2	2340
May	1st to 10th	Day	27% 38% 7% 15% 11% 3	2340
	11th to 20th	Day	27% 38% 7% 14% 12% 1	2436
	21st to end	Day	24% 38% 9% 16% 11% 2	2799
June	1st to 10th	Day	29% 38% 8% 16% 8% 1	2700
	11th to 20th	Day	24% 39% 8% 18% 11% 1	2700
	21st to end	Day	28% 39% 10% 15% 7% 1	2700
July	1st to 10th	Day	21% 40% 11% 19% 9% 1	2626
	11th to 20th	Day	22% 41% 10% 18% 9% 1	2619
	21st to end	Day	22% 41% 9% 20% 7%	2503
August	1st to 10th	Day	26% 39% 9% 17% 8% 1	2314
	11th to 20th	Day	20% 39% 13% 19% 8%	2303
	21st to end	Day	24% 39% 10% 18% 8% 1	2574
September	1st to 10th	Day	25% 39% 8% 20% 7% 1	2146
	11th to 20th	Day	25% 40% 11% 18% 6%	1980
	21st to end	Day	31% 38% 10% 16% 4	1980
October	1st to 10th	Day	30% 39% 9% 15% 6%	1832
	11th to 20th	Day	40% 38% 8% 8% 5%	1800
	21st to end	Day	41% 38% 10% 7% 4	1859
November	1st to 10th	Day	32% 41% 10% 13% 4	1605
	11th to 20th	Day	36% 41% 9% 10% 4	1520
	21st to end	Day	45% 42% 6% 5% 2	1520
December	1st to 10th	Day	40% 41% 10% 6% 2 1	1492
	11th to 20th	Day	43% 34% 10% 11% 2	1671
	21st to end	Day	59% 26% 7% 5% 2	2431
January	1st to 10th	Night	46% 32% 10% 8% 3	4748
	11th to 20th	Night	48% 30% 11% 8% 3	4500
	21st to end	Night	55% 25% 6% 10% 4	4678
February	1st to 10th	Night	39% 36% 8% 12% 4 1	2399
	11th to 20th	Night	37% 38% 9% 10% 4 1	2275
	21st to end	Night	39% 37% 9% 11% 5% 1	1816
March	1st to 10th	Night	30% 37% 10% 12% 9% 1	2067
	11th to 20th	Night	32% 38% 9% 13% 8% 1	1980
	21st to end	Night	31% 37% 8% 12% 10% 2	2178
April	1st to 10th	Night	32% 37% 7% 14% 9% 1	1861
	11th to 20th	Night	30% 36% 4 17% 12% 1	1597
	21st to end	Night	35% 36% 6% 10% 10% 2	1620
May	1st to 10th	Night	28% 37% 9% 13% 10% 3	1620
	11th to 20th	Night	26% 38% 6% 16% 11% 2	1462
	21st to end	Night	23% 39% 8% 15% 12% 3	1474
June	1st to 10th	Night	30% 39% 8% 13% 9% 1	1260
	11th to 20th	Night	24% 38% 8% 15% 14% 1	1260
	21st to end	Night	28% 38% 11% 15% 7% 1	1260
July	1st to 10th	Night	18% 39% 9% 21% 12% 1	1225
	11th to 20th	Night	22% 39% 9% 17% 12% 1	1218
	21st to end	Night	23% 41% 11% 17% 8%	1571
August	1st to 10th	Night	25% 39% 10% 17% 7% 1	1600
	11th to 20th	Night	21% 37% 11% 20% 10% 1	1598
	21st to end	Night	26% 37% 10% 17% 8% 2	1782
September	1st to 10th	Night	25% 37% 8% 19% 8% 2	1791
	11th to 20th	Night	24% 38% 12% 22% 4	1980
	21st to end	Night	29% 37% 11% 18% 5%	1980
October	1st to 10th	Night	31% 37% 9% 14% 9%	2127
	11th to 20th	Night	38% 38% 8% 13% 3	2160
	21st to end	Night	41% 38% 7% 9% 4	2492
November	1st to 10th	Night	30% 42% 9% 14% 5%	2472
	11th to 20th	Night	36% 41% 9% 8% 4	2660
	21st to end	Night	40% 42% 10% 7% 1	2660
December	1st to 10th	Night	42% 41% 8% 8% 1	2685
	11th to 20th	Night	43% 35% 10% 7% 4 1	3525
	21st to end	Night	58% 27% 8% 6% 2	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	28% 22% 31% 15% 5%	252
	11th to 20th	Day	25% 21% 38% 13% 2 1	240
	21st to end	Day	35% 23% 33% 9%	198
March	1st to 10th	Day	25% 20% 31% 18% 5% 1	332
	11th to 20th	Day	24% 12% 35% 21% 7% 1	420
	21st to end	Day	27% 13% 34% 19% 6% 1	462
April	1st to 10th	Day	25% 13% 30% 23% 8% 1	420
	11th to 20th	Day	29% 16% 26% 18% 8% 3	412
	21st to end	Day	31% 13% 29% 16% 9% 1	420
May	1st to 10th	Day	21% 13% 36% 20% 7% 3	423
	11th to 20th	Day	21% 12% 32% 19% 13% 3	447
	21st to end	Day	18% 9% 36% 24% 11% 2	559
June	1st to 10th	Day	18% 12% 35% 27% 7% 1	630
	11th to 20th	Day	18% 11% 36% 25% 9% 2	630
	21st to end	Day	20% 9% 32% 28% 9% 3	630
July	1st to 10th	Day	10% 9% 34% 33% 12% 2	621
	11th to 20th	Day	12% 10% 34% 29% 11% 4	618
	21st to end	Day	13% 6% 35% 29% 13% 4	585
August	1st to 10th	Day	17% 4 28% 30% 15% 6%	446
	11th to 20th	Day	13% 4 29% 31% 14% 10%	439
	21st to end	Day	16% 8% 29% 25% 14% 7%	495
September	1st to 10th	Day	15% 8% 31% 28% 13% 6%	450
	11th to 20th	Day	16% 6% 30% 32% 12% 4	450
	21st to end	Day	24% 11% 24% 26% 12% 3	450
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	20% 14% 36% 25% 5%	739
	11th to 20th	Night	20% 14% 33% 25% 7% 1	703
	21st to end	Night	22% 17% 34% 22% 5%	592
March	1st to 10th	Night	18% 17% 33% 24% 7%	720
	11th to 20th	Night	20% 13% 34% 22% 9% 1	720
	21st to end	Night	20% 10% 31% 30% 8% 1	792
April	1st to 10th	Night	24% 10% 32% 27% 6%	685
	11th to 20th	Night	24% 11% 25% 26% 11% 2	533
	21st to end	Night	25% 9% 26% 28% 12%	540
May	1st to 10th	Night	16% 6% 26% 37% 14% 1	540
	11th to 20th	Night	15% 8% 29% 34% 14% 1	400
	21st to end	Night	15% 5% 29% 34% 15% 2	389
June	1st to 10th	Night	19% 4 28% 37% 12% 1	360
	11th to 20th	Night	15% 6% 22% 41% 15% 1	360
	21st to end	Night	16% 3 24% 37% 18% 2	360
July	1st to 10th	Night	10% 5% 22% 47% 15% 1	350
	11th to 20th	Night	8% 3 21% 44% 22% 1	348
	21st to end	Night	10% 4 22% 41% 20% 2	581
August	1st to 10th	Night	13% 2 22% 36% 24% 2	537
	11th to 20th	Night	13% 2 22% 33% 25% 4	534
	21st to end	Night	15% 6% 22% 29% 25% 3	594
September	1st to 10th	Night	16% 5% 26% 31% 19% 3	685
	11th to 20th	Night	15% 6% 26% 29% 18% 5%	720
	21st to end	Night	21% 8% 25% 26% 17% 4	720
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

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