Fingal Wildlife Centre
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fingal Wildlife Centre clear sky chart from 2005-11-06 to 2025-11-03.

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% 5% 5% 4 6% 7% 33%	127385
	Night	15% 10% 4 8% 5% 5% 5% 4 5% 7% 33%	122643
Transparency	Day	48% 5% 14% 21% 12% 1	130983
	Night	49% 4 12% 21% 13% 1	127115
Seeing	Day	17% 7% 26% 28% 16% 6%	16305
	Night	20% 7% 26% 31% 15% 2	25350

By Month

Percentage Cloud Cover SE (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% 14% 5% 15% 8% 6% 5% 4 4 5% 21%	3946
	11th to 20th	Day	12% 20% 7% 16% 8% 7% 5% 3 6% 4 10%	4060
	21st to end	Day	20% 17% 6% 12% 6% 5% 5% 4 5% 5% 17%	4466
February	1st to 10th	Day	15% 16% 4 12% 8% 5% 5% 3 5% 6% 20%	1800
	11th to 20th	Day	15% 12% 5% 11% 8% 7% 5% 4 4 5% 23%	1763
	21st to end	Day	17% 12% 4 11% 7% 5% 6% 4 6% 5% 23%	1650
March	1st to 10th	Day	17% 10% 5% 13% 7% 5% 5% 4 5% 5% 25%	4815
	11th to 20th	Day	11% 10% 3 9% 6% 5% 5% 4 5% 8% 33%	4980
	21st to end	Day	18% 10% 3 9% 6% 5% 5% 3 5% 5% 30%	5465
April	1st to 10th	Day	16% 10% 4 8% 6% 5% 4 4 6% 7% 31%	2265
	11th to 20th	Day	17% 10% 3 7% 5% 5% 5% 3 5% 7% 33%	2553
	21st to end	Day	18% 8% 3 7% 5% 5% 4 3 5% 6% 36%	2600
May	1st to 10th	Day	18% 9% 3 8% 5% 5% 4 4 6% 7% 32%	5862
	11th to 20th	Day	15% 8% 3 8% 5% 5% 5% 5% 7% 9% 30%	5861
	21st to end	Day	15% 6% 3 7% 5% 5% 4 4 5% 7% 39%	6879
June	1st to 10th	Day	11% 6% 2 7% 6% 4 5% 5% 6% 8% 41%	2800
	11th to 20th	Day	9% 5% 3 6% 4 5% 6% 6% 8% 9% 40%	2945
	21st to end	Day	9% 5% 2 6% 4 4 5% 5% 8% 9% 42%	3000
July	1st to 10th	Day	7% 5% 2 7% 4 5% 5% 4 7% 11% 43%	6739
	11th to 20th	Day	7% 5% 2 6% 5% 4 5% 4 7% 10% 45%	5949
	21st to end	Day	7% 4 2 6% 5% 4 5% 5% 7% 9% 46%	6424
August	1st to 10th	Day	14% 5% 2 5% 4 4 5% 5% 7% 8% 40%	4234
	11th to 20th	Day	8% 6% 2 7% 5% 5% 7% 5% 8% 11% 36%	4174
	21st to end	Day	8% 6% 2 7% 5% 5% 5% 4 7% 9% 43%	4614
September	1st to 10th	Day	9% 6% 2 6% 4 5% 6% 4 6% 8% 44%	2333
	11th to 20th	Day	9% 5% 2 5% 4 4 5% 4 6% 8% 49%	2200
	21st to end	Day	18% 6% 2 6% 4 5% 4 4 7% 8% 37%	2200
October	1st to 10th	Day	14% 6% 2 7% 4 4 4 4 6% 8% 40%	2047
	11th to 20th	Day	18% 9% 2 7% 5% 4 5% 4 6% 8% 33%	2000
	21st to end	Day	22% 10% 3 8% 5% 5% 5% 3 6% 6% 26%	2167
November	1st to 10th	Day	13% 8% 2 8% 5% 6% 5% 4 7% 8% 34%	1780
	11th to 20th	Day	16% 10% 3 7% 5% 5% 5% 4 6% 7% 31%	1664
	21st to end	Day	20% 13% 4 10% 6% 6% 6% 4 6% 6% 20%	1600
December	1st to 10th	Day	20% 13% 3 10% 5% 5% 5% 4 7% 8% 20%	2600
	11th to 20th	Day	23% 16% 5% 10% 6% 4 4 4 6% 5% 17%	2990
	21st to end	Day	26% 19% 6% 12% 6% 5% 4 3 4 4 10%	3960
January	1st to 10th	Night	14% 13% 5% 12% 5% 5% 5% 4 5% 7% 25%	5981
	11th to 20th	Night	13% 18% 7% 16% 7% 6% 5% 4 7% 4 14%	5900
	21st to end	Night	20% 16% 6% 10% 5% 4 4 3 5% 6% 22%	6490
February	1st to 10th	Night	17% 16% 5% 10% 6% 5% 4 4 6% 6% 22%	2600
	11th to 20th	Night	17% 13% 5% 8% 6% 6% 4 4 5% 6% 26%	2520
	21st to end	Night	19% 11% 4 9% 7% 5% 5% 4 5% 6% 25%	1980
March	1st to 10th	Night	16% 10% 4 9% 6% 4 4 3 5% 6% 32%	5036
	11th to 20th	Night	10% 7% 3 7% 5% 5% 6% 3 6% 8% 40%	4980
	21st to end	Night	17% 10% 4 8% 4 4 4 3 4 5% 36%	5467
April	1st to 10th	Night	19% 10% 3 7% 4 5% 4 3 5% 6% 34%	2133
	11th to 20th	Night	17% 8% 3 7% 5% 5% 5% 3 5% 7% 36%	1812
	21st to end	Night	15% 8% 2 7% 5% 5% 5% 4 6% 7% 37%	1800
May	1st to 10th	Night	21% 10% 4 7% 4 4 4 3 5% 7% 32%	4033
	11th to 20th	Night	14% 9% 3 8% 6% 5% 5% 4 5% 6% 35%	4032
	21st to end	Night	16% 6% 3 5% 4 4 5% 4 6% 7% 41%	3974
June	1st to 10th	Night	12% 6% 2 6% 5% 3 4 4 7% 7% 45%	1600
	11th to 20th	Night	9% 5% 2 6% 4 5% 5% 4 8% 9% 43%	1449
	21st to end	Night	10% 4 1 5% 5% 5% 4 4 5% 8% 47%	1400
July	1st to 10th	Night	7% 4 2 6% 4 4 6% 4 6% 11% 46%	3220
	11th to 20th	Night	8% 5% 2 5% 4 4 4 3 6% 9% 49%	4005
	21st to end	Night	7% 5% 2 5% 4 4 4 4 6% 8% 51%	4427
August	1st to 10th	Night	11% 6% 2 6% 4 4 5% 4 7% 8% 44%	2915
	11th to 20th	Night	8% 6% 2 6% 4 4 4 4 5% 7% 50%	2875
	21st to end	Night	7% 4 2 6% 4 4 5% 3 6% 8% 49%	3251
September	1st to 10th	Night	8% 6% 3 7% 5% 4 5% 3 6% 6% 49%	2063
	11th to 20th	Night	9% 4 1 5% 3 4 4 4 5% 7% 55%	2200
	21st to end	Night	15% 6% 2 7% 4 5% 4 3 6% 6% 41%	2200
October	1st to 10th	Night	13% 5% 2 7% 4 3 4 3 5% 7% 46%	2351
	11th to 20th	Night	17% 9% 3 8% 4 4 4 4 5% 7% 37%	2400
	21st to end	Night	20% 9% 3 7% 4 4 4 4 6% 6% 32%	2670
November	1st to 10th	Night	14% 8% 2 6% 4 4 5% 4 5% 7% 41%	2563
	11th to 20th	Night	17% 9% 3 7% 5% 5% 6% 4 6% 7% 31%	2735
	21st to end	Night	21% 12% 3 8% 6% 4 4 4 6% 6% 26%	2800
December	1st to 10th	Night	16% 13% 6% 12% 7% 5% 6% 5% 6% 7% 18%	4580
	11th to 20th	Night	18% 19% 5% 10% 6% 5% 4 3 4 5% 21%	5205
	21st to end	Night	25% 17% 5% 12% 6% 5% 5% 3 4 5% 14%	6996

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	64% 3 14% 12% 7%	3947
	11th to 20th	Day	76% 2 10% 7% 5%	4060
	21st to end	Day	69% 4 13% 8% 6% 1	4466
February	1st to 10th	Day	66% 4 10% 14% 6% 1	1800
	11th to 20th	Day	62% 5% 8% 16% 8% 1	1772
	21st to end	Day	60% 5% 11% 17% 6% 1	1650
March	1st to 10th	Day	60% 4 14% 17% 5%	4815
	11th to 20th	Day	48% 4 18% 20% 8% 1	4980
	21st to end	Day	52% 6% 11% 20% 10% 1	5465
April	1st to 10th	Day	51% 4 12% 21% 13% 1	2265
	11th to 20th	Day	50% 4 12% 20% 13% 1	2553
	21st to end	Day	48% 4 12% 20% 13% 2	2600
May	1st to 10th	Day	50% 5% 11% 19% 10% 4	5897
	11th to 20th	Day	49% 6% 15% 20% 10% 1	5865
	21st to end	Day	42% 5% 12% 21% 16% 5%	6894
June	1st to 10th	Day	39% 5% 13% 27% 14% 2	2800
	11th to 20th	Day	37% 7% 15% 23% 17% 2	2945
	21st to end	Day	35% 6% 15% 27% 17% 1	3000
July	1st to 10th	Day	34% 5% 13% 28% 17% 2	6666
	11th to 20th	Day	32% 6% 15% 29% 17% 2	5878
	21st to end	Day	31% 7% 16% 25% 20% 2	6240
August	1st to 10th	Day	38% 6% 16% 24% 14% 1	4221
	11th to 20th	Day	38% 6% 17% 29% 9% 1	4213
	21st to end	Day	36% 5% 13% 32% 13% 1	4614
September	1st to 10th	Day	35% 5% 16% 27% 14% 2	2333
	11th to 20th	Day	32% 4 15% 33% 16%	2200
	21st to end	Day	44% 5% 13% 25% 13% 1	2200
October	1st to 10th	Day	33% 6% 15% 26% 20% 1	3333
	11th to 20th	Day	40% 4 13% 26% 16%	3240
	21st to end	Day	47% 4 17% 23% 8%	3481
November	1st to 10th	Day	47% 5% 12% 24% 9% 2	1780
	11th to 20th	Day	51% 4 17% 16% 11% 1	1664
	21st to end	Day	65% 3 14% 14% 3	1600
December	1st to 10th	Day	61% 6% 16% 13% 5%	2600
	11th to 20th	Day	68% 3 15% 8% 6%	2986
	21st to end	Day	77% 4 10% 7% 2	3960
January	1st to 10th	Night	59% 4 12% 17% 8%	5981
	11th to 20th	Night	72% 3 11% 10% 4	5900
	21st to end	Night	64% 3 11% 12% 10%	6490
February	1st to 10th	Night	62% 5% 11% 16% 6% 1	2600
	11th to 20th	Night	58% 4 11% 18% 9% 1	2522
	21st to end	Night	59% 3 9% 20% 8% 1	1980
March	1st to 10th	Night	52% 3 14% 19% 10% 1	5036
	11th to 20th	Night	41% 4 16% 24% 14% 1	4980
	21st to end	Night	49% 4 10% 18% 17% 1	5467
April	1st to 10th	Night	51% 3 9% 20% 14% 2	2133
	11th to 20th	Night	47% 4 9% 23% 16% 2	1812
	21st to end	Night	45% 4 10% 21% 17% 3	1800
May	1st to 10th	Night	53% 3 9% 15% 12% 8%	4060
	11th to 20th	Night	49% 4 11% 22% 11% 3	4033
	21st to end	Night	41% 4 13% 22% 18% 2	3981
June	1st to 10th	Night	38% 4 11% 28% 17% 4	1600
	11th to 20th	Night	36% 3 14% 26% 18% 3	1449
	21st to end	Night	35% 6% 11% 25% 21% 1	1400
July	1st to 10th	Night	32% 5% 14% 27% 17% 5%	3186
	11th to 20th	Night	32% 5% 12% 30% 19% 2	3956
	21st to end	Night	30% 5% 13% 22% 26% 4	4297
August	1st to 10th	Night	36% 5% 14% 27% 17% 2	2904
	11th to 20th	Night	33% 5% 14% 32% 14% 1	2902
	21st to end	Night	32% 5% 11% 35% 16% 1	3251
September	1st to 10th	Night	34% 5% 12% 31% 16% 2	2063
	11th to 20th	Night	29% 3 12% 34% 20% 2	2200
	21st to end	Night	44% 4 12% 26% 14% 1	2200
October	1st to 10th	Night	28% 3 10% 31% 27% 2	3845
	11th to 20th	Night	42% 4 13% 23% 18%	3899
	21st to end	Night	41% 3 16% 26% 13% 1	4306
November	1st to 10th	Night	42% 4 12% 26% 15% 1	2563
	11th to 20th	Night	52% 3 13% 20% 10% 1	2735
	21st to end	Night	59% 3 17% 17% 4 1	2800
December	1st to 10th	Night	63% 6% 15% 12% 3	4580
	11th to 20th	Night	65% 3 13% 12% 7%	5208
	21st to end	Night	73% 3 12% 9% 3	6996

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	22% 13% 36% 22% 5% 2	277
	11th to 20th	Day	22% 11% 42% 17% 6% 2	300
	21st to end	Day	26% 10% 32% 26% 5% 1	330
February	1st to 10th	Day	20% 14% 39% 23% 3	300
	11th to 20th	Day	22% 15% 34% 24% 4	300
	21st to end	Day	22% 19% 36% 21% 2	249
March	1st to 10th	Day	19% 11% 36% 25% 9%	441
	11th to 20th	Day	16% 12% 33% 29% 8% 1	500
	21st to end	Day	25% 9% 33% 25% 7% 1	550
April	1st to 10th	Day	20% 8% 33% 28% 8% 1	500
	11th to 20th	Day	24% 9% 33% 20% 10% 4	492
	21st to end	Day	22% 7% 31% 27% 10% 3	500
May	1st to 10th	Day	22% 6% 27% 30% 12% 4	503
	11th to 20th	Day	17% 5% 23% 29% 19% 7%	527
	21st to end	Day	14% 2 24% 29% 21% 9%	573
June	1st to 10th	Day	13% 3 27% 35% 16% 6%	530
	11th to 20th	Day	9% 4 24% 36% 23% 4	675
	21st to end	Day	12% 2 24% 36% 20% 5%	730
July	1st to 10th	Day	9% 3 18% 33% 26% 12%	721
	11th to 20th	Day	13% 3 20% 29% 24% 12%	545
	21st to end	Day	9% 1 13% 38% 28% 10%	576
August	1st to 10th	Day	9% 2 14% 34% 25% 16%	526
	11th to 20th	Day	10% 2 13% 36% 27% 13%	519
	21st to end	Day	12% 1 13% 35% 28% 10%	583
September	1st to 10th	Day	12% 3 17% 30% 26% 12%	530
	11th to 20th	Day	8% 1 12% 25% 35% 18%	530
	21st to end	Day	19% 4 20% 26% 23% 8%	530
October	1st to 10th	Day	17% 5% 23% 24% 23% 8%	530
	11th to 20th	Day	19% 9% 32% 29% 9% 3	530
	21st to end	Day	25% 10% 32% 24% 9% 1	550
November	1st to 10th	Day	18% 10% 34% 23% 11% 3	306
	11th to 20th	Day	22% 16% 35% 21% 5% 3	232
	21st to end	Day	24% 12% 37% 24% 4	200
December	1st to 10th	Day	25% 13% 34% 20% 7% 1	200
	11th to 20th	Day	31% 19% 28% 17% 5%	200
	21st to end	Day	30% 13% 31% 21% 4	220
January	1st to 10th	Night	25% 14% 36% 19% 6% 1	800
	11th to 20th	Night	29% 13% 30% 23% 6%	800
	21st to end	Night	23% 9% 34% 28% 6%	880
February	1st to 10th	Night	25% 9% 34% 28% 4	800
	11th to 20th	Night	23% 10% 33% 28% 5% 1	783
	21st to end	Night	23% 9% 38% 26% 4	660
March	1st to 10th	Night	20% 8% 34% 30% 7%	800
	11th to 20th	Night	20% 6% 36% 29% 9% 1	800
	21st to end	Night	23% 7% 30% 30% 10% 1	880
April	1st to 10th	Night	24% 8% 29% 31% 7% 1	800
	11th to 20th	Night	21% 6% 32% 29% 11% 1	628
	21st to end	Night	19% 4 32% 34% 11% 1	600
May	1st to 10th	Night	21% 4 25% 34% 15% 2	600
	11th to 20th	Night	14% 3 23% 40% 18% 3	591
	21st to end	Night	15% 2 19% 35% 24% 4	462
June	1st to 10th	Night	16% 1 22% 39% 20% 3	400
	11th to 20th	Night	12% 2 20% 41% 24% 2	400
	21st to end	Night	11% 1 20% 44% 23% 2	400
July	1st to 10th	Night	7% 1 13% 42% 33% 5%	412
	11th to 20th	Night	14% 1 11% 40% 29% 6%	582
	21st to end	Night	9% 1 11% 45% 30% 4	657
August	1st to 10th	Night	9% 1 12% 38% 35% 5%	597
	11th to 20th	Night	8% 1 11% 38% 37% 6%	594
	21st to end	Night	12% 15% 38% 29% 5%	675
September	1st to 10th	Night	10% 3 17% 32% 29% 9%	800
	11th to 20th	Night	11% 3 11% 33% 35% 7%	800
	21st to end	Night	18% 3 19% 34% 18% 7%	800
October	1st to 10th	Night	17% 4 22% 33% 20% 5%	800
	11th to 20th	Night	21% 8% 29% 27% 14% 1	800
	21st to end	Night	25% 9% 31% 28% 7%	880
November	1st to 10th	Night	18% 10% 25% 31% 14% 1	789
	11th to 20th	Night	22% 12% 34% 22% 7% 2	800
	21st to end	Night	28% 11% 30% 24% 7%	800
December	1st to 10th	Night	28% 13% 32% 20% 6% 1	800
	11th to 20th	Night	26% 15% 34% 21% 5%	800
	21st to end	Night	31% 10% 30% 26% 3	880

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