Little Cayman Island
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Little Cayman Island clear sky chart from 2005-11-06 to 2025-12-03.

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
Transparency	Day	25% 10% 26% 26% 11% 1	130087
	Night	26% 9% 24% 27% 13% 1	128515
Seeing	Day	5% 1 5% 20% 43% 26%	18854
	Night	6% 1 5% 19% 42% 26%	29026

By Month

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	30% 8% 16% 29% 17% 1	4516
	11th to 20th	Day	19% 6% 14% 40% 21% 1	4681
	21st to end	Day	19% 7% 13% 40% 20%	5478
February	1st to 10th	Day	22% 6% 11% 28% 28% 4	2200
	11th to 20th	Day	23% 5% 11% 28% 28% 5%	2153
	21st to end	Day	18% 5% 8% 25% 34% 10%	1815
March	1st to 10th	Day	17% 6% 11% 40% 24% 2	4935
	11th to 20th	Day	16% 5% 9% 32% 35% 4	4980
	21st to end	Day	14% 6% 12% 37% 28% 2	5465
April	1st to 10th	Day	23% 7% 18% 33% 19% 1	2200
	11th to 20th	Day	21% 7% 19% 40% 12% 1	2176
	21st to end	Day	22% 7% 19% 40% 11% 1	2387
May	1st to 10th	Day	15% 8% 17% 48% 12%	5437
	11th to 20th	Day	21% 9% 26% 35% 8%	5408
	21st to end	Day	23% 9% 23% 39% 6%	5944
June	1st to 10th	Day	51% 12% 29% 7% 1	2400
	11th to 20th	Day	40% 14% 34% 12% 1	2400
	21st to end	Day	33% 14% 39% 14%	2400
July	1st to 10th	Day	26% 13% 48% 13%	5634
	11th to 20th	Day	15% 12% 56% 17% 1	5376
	21st to end	Day	20% 13% 49% 17% 1	5754
August	1st to 10th	Day	24% 13% 50% 12%	3734
	11th to 20th	Day	19% 13% 45% 22% 1	3558
	21st to end	Day	26% 17% 48% 9%	3949
September	1st to 10th	Day	28% 17% 38% 17% 1	2200
	11th to 20th	Day	30% 15% 41% 13%	2200
	21st to end	Day	33% 17% 35% 14% 1	2200
October	1st to 10th	Day	32% 15% 34% 18% 1	3473
	11th to 20th	Day	34% 18% 33% 13% 1	3240
	21st to end	Day	42% 12% 18% 20% 8% 1	3538
November	1st to 10th	Day	45% 9% 18% 17% 10%	2057
	11th to 20th	Day	38% 10% 18% 19% 13% 1	2100
	21st to end	Day	34% 9% 12% 27% 17% 1	2100
December	1st to 10th	Day	33% 8% 15% 29% 14%	3280
	11th to 20th	Day	25% 10% 21% 28% 14% 2	3747
	21st to end	Day	39% 9% 22% 20% 9% 1	4972
January	1st to 10th	Night	30% 8% 17% 30% 15% 1	5430
	11th to 20th	Night	19% 7% 10% 41% 22% 1	5274
	21st to end	Night	18% 6% 10% 43% 23% 1	5478
February	1st to 10th	Night	23% 5% 10% 28% 30% 3	2200
	11th to 20th	Night	23% 5% 12% 29% 28% 4	2144
	21st to end	Night	18% 5% 6% 26% 35% 11%	1815
March	1st to 10th	Night	10% 4 8% 43% 32% 3	4918
	11th to 20th	Night	13% 5% 7% 28% 40% 6%	4980
	21st to end	Night	17% 6% 10% 33% 28% 6%	5467
April	1st to 10th	Night	19% 5% 14% 37% 24% 1	2200
	11th to 20th	Night	20% 6% 15% 40% 18% 1	2173
	21st to end	Night	21% 5% 17% 40% 16% 1	2010
May	1st to 10th	Night	15% 7% 13% 45% 20%	4520
	11th to 20th	Night	27% 8% 21% 33% 11%	4491
	21st to end	Night	24% 7% 22% 41% 6%	4931
June	1st to 10th	Night	51% 11% 27% 11% 1	2000
	11th to 20th	Night	41% 13% 32% 14% 1	2000
	21st to end	Night	33% 14% 34% 19%	2000
July	1st to 10th	Night	28% 12% 46% 13% 1	4025
	11th to 20th	Night	15% 10% 56% 18% 1	4455
	21st to end	Night	15% 11% 48% 24% 2	4785
August	1st to 10th	Night	29% 13% 45% 13% 1	3381
	11th to 20th	Night	20% 9% 43% 26% 2	3555
	21st to end	Night	26% 14% 47% 13%	3949
September	1st to 10th	Night	30% 14% 35% 20% 1	2200
	11th to 20th	Night	30% 13% 41% 16%	2200
	21st to end	Night	35% 12% 36% 16% 1	2200
October	1st to 10th	Night	31% 15% 35% 18% 2	3706
	11th to 20th	Night	36% 13% 39% 10% 1	3899
	21st to end	Night	41% 11% 21% 18% 9%	4252
November	1st to 10th	Night	48% 9% 17% 19% 7%	2461
	11th to 20th	Night	40% 9% 18% 20% 12% 1	2520
	21st to end	Night	39% 6% 11% 23% 20% 2	2520
December	1st to 10th	Night	36% 8% 13% 31% 13%	3945
	11th to 20th	Night	27% 10% 20% 26% 14% 2	4447
	21st to end	Night	37% 8% 24% 20% 10% 1	5984

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	7% 1 8% 29% 45% 11%	500
	11th to 20th	Day	5% 2 9% 37% 38% 8%	500
	21st to end	Day	3 1 11% 34% 45% 7%	550
February	1st to 10th	Day	3 2 9% 37% 45% 5%	500
	11th to 20th	Day	3 9% 30% 49% 9%	496
	21st to end	Day	4 1 7% 29% 48% 10%	414
March	1st to 10th	Day	4 2 10% 33% 42% 9%	500
	11th to 20th	Day	4 1 7% 29% 47% 11%	500
	21st to end	Day	3 2 8% 35% 44% 9%	550
April	1st to 10th	Day	3 1 4 25% 54% 14%	500
	11th to 20th	Day	2 7% 34% 45% 11%	492
	21st to end	Day	3 4 31% 48% 14%	500
May	1st to 10th	Day	2 1 2 26% 53% 15%	503
	11th to 20th	Day	6% 1 4 16% 54% 19%	527
	21st to end	Day	8% 2 6% 15% 50% 20%	573
June	1st to 10th	Day	14% 3 5% 18% 41% 19%	530
	11th to 20th	Day	8% 2 3 13% 49% 25%	530
	21st to end	Day	5% 1 3 10% 46% 35%	530
July	1st to 10th	Day	2 2 7% 51% 38%	525
	11th to 20th	Day	1 4 48% 46%	524
	21st to end	Day	2 6% 45% 48%	576
August	1st to 10th	Day	2 1 6% 41% 50%	526
	11th to 20th	Day	2 1 1 7% 37% 52%	519
	21st to end	Day	5% 1 2 7% 33% 52%	583
September	1st to 10th	Day	4 1 5% 28% 61%	530
	11th to 20th	Day	1 1 2 3 26% 68%	530
	21st to end	Day	4 1 2 6% 31% 55%	530
October	1st to 10th	Day	6% 1 4 10% 35% 44%	530
	11th to 20th	Day	4 1 2 8% 39% 46%	530
	21st to end	Day	8% 1 5% 23% 39% 24%	583
November	1st to 10th	Day	12% 2 4 21% 48% 14%	535
	11th to 20th	Day	9% 1 7% 22% 42% 19%	540
	21st to end	Day	5% 1 12% 26% 40% 16%	540
December	1st to 10th	Day	4 1 4 26% 52% 12%	508
	11th to 20th	Day	6% 1 7% 36% 41% 10%	500
	21st to end	Day	6% 1 9% 37% 39% 7%	550
January	1st to 10th	Night	5% 1 9% 30% 43% 13%	800
	11th to 20th	Night	8% 2 13% 30% 41% 7%	800
	21st to end	Night	5% 1 9% 33% 42% 11%	880
February	1st to 10th	Night	4 2 11% 30% 44% 10%	800
	11th to 20th	Night	5% 1 9% 28% 44% 12%	783
	21st to end	Night	4 1 5% 29% 45% 17%	660
March	1st to 10th	Night	3 1 8% 32% 43% 12%	800
	11th to 20th	Night	3 1 6% 28% 50% 13%	800
	21st to end	Night	4 2 10% 27% 42% 15%	880
April	1st to 10th	Night	2 1 4 22% 56% 16%	800
	11th to 20th	Night	3 1 7% 26% 44% 18%	791
	21st to end	Night	4 1 7% 24% 49% 16%	800
May	1st to 10th	Night	4 1 5% 23% 48% 19%	800
	11th to 20th	Night	8% 1 3 18% 52% 19%	789
	21st to end	Night	12% 2 5% 16% 46% 20%	866
June	1st to 10th	Night	13% 1 5% 13% 44% 24%	800
	11th to 20th	Night	8% 2 3 14% 46% 28%	800
	21st to end	Night	5% 2 2 12% 44% 36%	800
July	1st to 10th	Night	4 1 1 7% 53% 33%	595
	11th to 20th	Night	2 7% 44% 46%	771
	21st to end	Night	1 1 6% 47% 44%	875
August	1st to 10th	Night	3 1 7% 40% 48%	797
	11th to 20th	Night	5% 1 2 5% 36% 51%	790
	21st to end	Night	5% 2 9% 39% 46%	880
September	1st to 10th	Night	5% 1 2 7% 22% 63%	800
	11th to 20th	Night	5% 1 1 5% 27% 62%	800
	21st to end	Night	7% 1 2 8% 26% 56%	800
October	1st to 10th	Night	11% 3 13% 32% 41%	800
	11th to 20th	Night	8% 3 9% 33% 47%	800
	21st to end	Night	11% 1 7% 19% 36% 27%	880
November	1st to 10th	Night	15% 2 9% 23% 37% 15%	820
	11th to 20th	Night	9% 1 7% 21% 43% 19%	840
	21st to end	Night	9% 1 11% 26% 39% 14%	840
December	1st to 10th	Night	6% 1 8% 27% 46% 12%	809
	11th to 20th	Night	9% 2 7% 30% 42% 10%	800
	21st to end	Night	7% 2 9% 31% 42% 10%	880

Page generated at 2025-11-30 01:00:53. Version ac07

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