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 2024-11-11.

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	27% 11% 26% 24% 11% 1	104063
	Night	28% 9% 24% 25% 12% 1	103075
Seeing	Day	5% 1 5% 20% 43% 25%	17306
	Night	6% 1 6% 19% 42% 26%	27490

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	22% 8% 11% 35% 25% 1	3156
	11th to 20th	Day	22% 6% 15% 40% 15% 1	3265
	21st to end	Day	23% 8% 16% 35% 17% 1	3828
February	1st to 10th	Day	23% 6% 12% 26% 29% 4	2090
	11th to 20th	Day	24% 5% 11% 26% 29% 5%	2043
	21st to end	Day	18% 4 7% 25% 35% 10%	1727
March	1st to 10th	Day	18% 7% 13% 39% 20% 3	3435
	11th to 20th	Day	17% 6% 11% 40% 25% 1	3480
	21st to end	Day	18% 7% 11% 28% 32% 3	3815
April	1st to 10th	Day	23% 7% 17% 33% 18% 1	2090
	11th to 20th	Day	21% 8% 19% 41% 10%	2066
	21st to end	Day	23% 7% 19% 41% 10%	2267
May	1st to 10th	Day	20% 9% 19% 37% 15%	3800
	11th to 20th	Day	24% 9% 27% 31% 9%	3768
	21st to end	Day	32% 10% 18% 32% 8%	4140
June	1st to 10th	Day	52% 13% 28% 7% 1	2280
	11th to 20th	Day	42% 14% 34% 9% 1	2280
	21st to end	Day	32% 14% 39% 15%	2280
July	1st to 10th	Day	30% 13% 43% 14%	3910
	11th to 20th	Day	17% 14% 55% 14%	3736
	21st to end	Day	21% 14% 49% 15%	3988
August	1st to 10th	Day	25% 13% 50% 12%	3619
	11th to 20th	Day	19% 14% 45% 21% 1	3448
	21st to end	Day	27% 17% 47% 9%	3828
September	1st to 10th	Day	28% 17% 36% 17% 1	2090
	11th to 20th	Day	31% 15% 40% 14%	2090
	21st to end	Day	34% 17% 34% 14% 1	2090
October	1st to 10th	Day	32% 15% 33% 19% 1	3366
	11th to 20th	Day	35% 18% 33% 13% 1	3140
	21st to end	Day	42% 12% 19% 19% 7% 1	3428
November	1st to 10th	Day	46% 9% 16% 18% 11%	1957
	11th to 20th	Day	39% 10% 19% 19% 12% 1	1900
	21st to end	Day	35% 9% 12% 26% 17% 1	1900
December	1st to 10th	Day	29% 7% 14% 28% 22% 1	1900
	11th to 20th	Day	31% 9% 12% 27% 17% 3	2387
	21st to end	Day	36% 8% 21% 21% 13% 2	3476
January	1st to 10th	Night	24% 7% 12% 33% 22% 1	3790
	11th to 20th	Night	22% 8% 12% 41% 16% 1	3690
	21st to end	Night	20% 7% 11% 40% 21% 1	3828
February	1st to 10th	Night	24% 5% 10% 27% 31% 3	2090
	11th to 20th	Night	23% 5% 12% 26% 29% 5%	2034
	21st to end	Night	17% 4 6% 25% 37% 11%	1727
March	1st to 10th	Night	12% 6% 11% 46% 22% 4	3418
	11th to 20th	Night	15% 6% 9% 34% 35% 1	3480
	21st to end	Night	21% 6% 10% 25% 32% 5%	3817
April	1st to 10th	Night	19% 6% 14% 37% 23% 1	2090
	11th to 20th	Night	21% 6% 15% 41% 16%	2063
	21st to end	Night	22% 5% 17% 40% 15%	1910
May	1st to 10th	Night	18% 8% 17% 39% 18%	3160
	11th to 20th	Night	29% 9% 23% 32% 8%	3131
	21st to end	Night	32% 8% 17% 35% 9%	3435
June	1st to 10th	Night	52% 11% 26% 10% 1	1900
	11th to 20th	Night	43% 14% 32% 12%	1900
	21st to end	Night	32% 13% 34% 20%	1900
July	1st to 10th	Night	30% 12% 41% 15% 2	2805
	11th to 20th	Night	17% 11% 53% 18%	3095
	21st to end	Night	19% 13% 50% 18%	3326
August	1st to 10th	Night	29% 13% 45% 12% 1	3276
	11th to 20th	Night	20% 9% 44% 26% 2	3445
	21st to end	Night	26% 15% 46% 13%	3828
September	1st to 10th	Night	30% 15% 33% 21% 1	2090
	11th to 20th	Night	31% 13% 39% 17%	2090
	21st to end	Night	36% 12% 36% 15% 1	2090
October	1st to 10th	Night	32% 15% 34% 18% 2	3593
	11th to 20th	Night	36% 13% 40% 10% 1	3779
	21st to end	Night	42% 11% 21% 17% 9%	4120
November	1st to 10th	Night	50% 8% 16% 19% 7%	2341
	11th to 20th	Night	41% 9% 18% 20% 12% 1	2287
	21st to end	Night	39% 6% 11% 23% 20% 1	2280
December	1st to 10th	Night	32% 8% 12% 28% 21%	2280
	11th to 20th	Night	34% 10% 11% 24% 17% 4	2807
	21st to end	Night	36% 8% 20% 21% 14% 1	4180

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 7% 29% 45% 12%	460
	11th to 20th	Day	6% 2 10% 39% 36% 7%	460
	21st to end	Day	3 1 11% 34% 43% 7%	506
February	1st to 10th	Day	3 2 9% 38% 43% 4	460
	11th to 20th	Day	4 9% 30% 47% 9%	456
	21st to end	Day	4 1 8% 29% 49% 10%	382
March	1st to 10th	Day	4 2 11% 33% 42% 8%	460
	11th to 20th	Day	4 1 8% 29% 47% 11%	460
	21st to end	Day	3 2 9% 34% 43% 10%	506
April	1st to 10th	Day	3 1 4 26% 52% 15%	460
	11th to 20th	Day	2 6% 31% 49% 12%	452
	21st to end	Day	3 4 31% 47% 15%	460
May	1st to 10th	Day	2 2 3 26% 52% 16%	463
	11th to 20th	Day	6% 1 5% 17% 53% 17%	487
	21st to end	Day	9% 2 6% 16% 49% 18%	529
June	1st to 10th	Day	14% 3 6% 19% 40% 18%	490
	11th to 20th	Day	9% 2 3 13% 49% 25%	490
	21st to end	Day	4 1 3 9% 44% 38%	490
July	1st to 10th	Day	2 2 7% 50% 38%	485
	11th to 20th	Day	1 4 48% 47%	484
	21st to end	Day	2 5% 45% 48%	532
August	1st to 10th	Day	3 1 6% 42% 48%	486
	11th to 20th	Day	2 1 1 7% 37% 52%	479
	21st to end	Day	6% 1 2 8% 34% 50%	539
September	1st to 10th	Day	4 1 6% 30% 58%	490
	11th to 20th	Day	1 1 2 3 27% 66%	490
	21st to end	Day	5% 1 2 6% 32% 53%	490
October	1st to 10th	Day	6% 1 4 11% 38% 40%	490
	11th to 20th	Day	5% 1 2 9% 40% 44%	490
	21st to end	Day	9% 1 4 23% 37% 26%	539
November	1st to 10th	Day	13% 2 4 23% 45% 13%	495
	11th to 20th	Day	8% 8% 22% 44% 18%	460
	21st to end	Day	5% 1 13% 24% 40% 17%	460
December	1st to 10th	Day	5% 4 26% 53% 13%	460
	11th to 20th	Day	7% 1 7% 35% 40% 10%	460
	21st to end	Day	6% 1 10% 37% 40% 7%	506
January	1st to 10th	Night	5% 1 8% 29% 44% 13%	760
	11th to 20th	Night	8% 1 13% 30% 40% 7%	760
	21st to end	Night	5% 1 9% 33% 41% 11%	836
February	1st to 10th	Night	4 2 11% 30% 43% 10%	760
	11th to 20th	Night	5% 1 9% 29% 43% 12%	743
	21st to end	Night	4 1 4 27% 46% 17%	628
March	1st to 10th	Night	3 1 9% 33% 42% 12%	760
	11th to 20th	Night	3 1 6% 28% 50% 13%	760
	21st to end	Night	4 2 10% 25% 43% 15%	836
April	1st to 10th	Night	2 1 4 21% 55% 17%	760
	11th to 20th	Night	3 1 7% 24% 46% 19%	751
	21st to end	Night	4 1 7% 23% 49% 16%	760
May	1st to 10th	Night	4 1 5% 23% 47% 19%	760
	11th to 20th	Night	8% 1 3 18% 52% 17%	749
	21st to end	Night	12% 2 5% 17% 45% 19%	822
June	1st to 10th	Night	13% 1 5% 14% 44% 23%	760
	11th to 20th	Night	8% 2 3 13% 45% 29%	760
	21st to end	Night	4 1 2 11% 44% 37%	760
July	1st to 10th	Night	4 1 1 7% 53% 34%	565
	11th to 20th	Night	2 7% 44% 46%	731
	21st to end	Night	2 1 6% 47% 44%	831
August	1st to 10th	Night	3 1 7% 41% 47%	757
	11th to 20th	Night	5% 1 2 5% 35% 52%	750
	21st to end	Night	5% 2 9% 40% 44%	836
September	1st to 10th	Night	5% 1 2 7% 23% 62%	760
	11th to 20th	Night	5% 1 1 5% 27% 62%	760
	21st to end	Night	7% 1 2 8% 26% 56%	760
October	1st to 10th	Night	11% 3 13% 34% 38%	760
	11th to 20th	Night	8% 3 9% 34% 46%	760
	21st to end	Night	12% 1 6% 18% 35% 28%	836
November	1st to 10th	Night	16% 2 9% 24% 36% 13%	780
	11th to 20th	Night	9% 1 7% 21% 44% 18%	763
	21st to end	Night	9% 1 12% 25% 38% 15%	760
December	1st to 10th	Night	6% 1 7% 27% 47% 12%	760
	11th to 20th	Night	9% 2 7% 30% 42% 10%	760
	21st to end	Night	7% 2 9% 30% 42% 10%	836

Page generated at 2024-11-08 06:44:48. Version ac07

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