Bahama
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bahama clear sky chart from 2005-11-06 to 2025-08-05.

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	13% 6% 2 6% 4 4 5% 4 6% 8% 43%	124939
	Night	14% 6% 2 6% 4 4 4 4 5% 7% 45%	123135
Transparency	Day	39% 4 12% 22% 18% 5%	128544
	Night	39% 3 10% 21% 21% 6%	127599
Seeing	Day	18% 10% 25% 24% 17% 6%	16260
	Night	17% 9% 25% 31% 17% 2	26609

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	15% 6% 2 5% 3 2 2 2 3 4 57%	4056
	11th to 20th	Day	12% 6% 2 5% 3 2 3 2 4 4 57%	4060
	21st to end	Day	14% 8% 3 6% 3 4 4 3 4 4 47%	4466
February	1st to 10th	Day	14% 6% 2 6% 5% 4 4 5% 5% 7% 44%	1800
	11th to 20th	Day	22% 7% 2 5% 4 3 4 3 4 5% 44%	1758
	21st to end	Day	18% 8% 2 6% 4 3 3 3 4 5% 42%	1795
March	1st to 10th	Day	19% 7% 2 5% 4 4 4 3 5% 7% 40%	4935
	11th to 20th	Day	10% 6% 2 5% 3 3 3 3 4 7% 53%	4980
	21st to end	Day	15% 6% 2 6% 5% 4 5% 3 4 6% 46%	5465
April	1st to 10th	Day	10% 5% 1 4 3 3 4 3 6% 8% 53%	2326
	11th to 20th	Day	10% 5% 2 5% 5% 4 4 3 5% 7% 50%	2374
	21st to end	Day	14% 6% 2 5% 4 4 5% 4 6% 7% 44%	2400
May	1st to 10th	Day	9% 7% 2 7% 5% 6% 5% 5% 8% 11% 34%	5849
	11th to 20th	Day	19% 6% 3 8% 5% 5% 6% 5% 7% 9% 29%	5861
	21st to end	Day	13% 5% 2 5% 4 5% 5% 4 6% 8% 42%	6433
June	1st to 10th	Day	10% 5% 2 5% 5% 5% 5% 5% 6% 10% 42%	2600
	11th to 20th	Day	8% 5% 2 5% 5% 5% 4 4 6% 10% 46%	2600
	21st to end	Day	7% 4 2 5% 5% 5% 5% 5% 9% 12% 41%	2600
July	1st to 10th	Day	8% 5% 2 7% 5% 6% 6% 5% 8% 12% 36%	5900
	11th to 20th	Day	9% 5% 3 7% 5% 6% 7% 6% 10% 13% 29%	5900
	21st to end	Day	8% 6% 3 7% 6% 6% 7% 5% 7% 11% 35%	6424
August	1st to 10th	Day	19% 8% 2 8% 6% 6% 6% 5% 7% 10% 24%	4156
	11th to 20th	Day	8% 6% 3 7% 6% 6% 7% 5% 8% 10% 36%	3926
	21st to end	Day	7% 4 2 5% 4 4 5% 4 6% 10% 50%	4180
September	1st to 10th	Day	10% 5% 2 6% 5% 4 5% 4 7% 7% 45%	2280
	11th to 20th	Day	15% 6% 3 6% 4 5% 5% 4 5% 7% 41%	2154
	21st to end	Day	22% 7% 2 6% 4 3 3 3 5% 7% 38%	2047
October	1st to 10th	Day	15% 5% 2 5% 3 3 3 3 4 6% 50%	1900
	11th to 20th	Day	14% 4 2 4 3 3 3 3 4 4 57%	1900
	21st to end	Day	11% 4 1 5% 3 3 3 2 3 5% 58%	2090
November	1st to 10th	Day	13% 4 2 5% 4 4 4 3 4 4 54%	1957
	11th to 20th	Day	14% 5% 2 5% 3 3 3 3 5% 6% 52%	1975
	21st to end	Day	14% 5% 2 5% 4 3 3 3 5% 6% 51%	1644
December	1st to 10th	Day	12% 6% 2 5% 3 3 3 3 4 5% 52%	2600
	11th to 20th	Day	16% 6% 2 7% 4 3 3 3 4 5% 46%	3082
	21st to end	Day	17% 5% 2 5% 3 3 4 3 5% 7% 45%	4466
January	1st to 10th	Night	13% 6% 2 5% 3 3 3 3 5% 5% 55%	5889
	11th to 20th	Night	13% 6% 2 4 3 2 3 3 4 4 57%	5900
	21st to end	Night	15% 7% 2 5% 3 3 3 3 4 5% 49%	6490
February	1st to 10th	Night	17% 6% 2 5% 3 4 4 4 4 6% 45%	2600
	11th to 20th	Night	19% 8% 2 4 3 3 3 4 5% 5% 43%	2527
	21st to end	Night	14% 7% 1 5% 4 3 4 3 5% 6% 47%	1832
March	1st to 10th	Night	19% 7% 2 6% 4 4 3 3 4 5% 43%	4918
	11th to 20th	Night	12% 5% 2 4 3 3 3 3 4 7% 54%	4980
	21st to end	Night	13% 5% 2 5% 3 4 4 4 5% 6% 49%	5467
April	1st to 10th	Night	14% 5% 2 4 4 4 4 4 5% 6% 49%	2072
	11th to 20th	Night	12% 4 2 4 4 4 4 3 5% 6% 51%	1975
	21st to end	Night	12% 5% 2 6% 5% 4 4 4 6% 7% 46%	2000
May	1st to 10th	Night	13% 7% 3 8% 5% 5% 5% 4 6% 8% 36%	4088
	11th to 20th	Night	20% 8% 3 7% 4 4 3 3 5% 8% 33%	4032
	21st to end	Night	15% 6% 2 5% 4 4 4 4 6% 9% 43%	4421
June	1st to 10th	Night	10% 5% 2 6% 4 4 5% 5% 8% 10% 41%	1800
	11th to 20th	Night	9% 6% 2 6% 5% 5% 5% 4 7% 10% 42%	1800
	21st to end	Night	7% 4 2 6% 5% 6% 6% 5% 7% 12% 41%	1800
July	1st to 10th	Night	12% 6% 2 7% 5% 5% 6% 5% 8% 12% 32%	4058
	11th to 20th	Night	12% 7% 3 8% 6% 5% 7% 6% 8% 11% 27%	4057
	21st to end	Night	11% 8% 3 8% 5% 5% 5% 5% 7% 11% 32%	4427
August	1st to 10th	Night	21% 7% 3 6% 5% 5% 6% 5% 8% 11% 23%	2861
	11th to 20th	Night	7% 4 3 6% 6% 6% 6% 5% 8% 10% 39%	2870
	21st to end	Night	7% 4 2 6% 4 5% 4 4 6% 8% 50%	3476
September	1st to 10th	Night	12% 5% 2 6% 4 4 3 4 5% 7% 48%	1900
	11th to 20th	Night	15% 6% 2 6% 4 4 4 4 6% 6% 43%	2023
	21st to end	Night	23% 7% 2 6% 3 4 3 4 5% 6% 37%	2133
October	1st to 10th	Night	15% 7% 2 5% 4 3 3 3 4 5% 47%	2280
	11th to 20th	Night	14% 6% 2 4 3 3 3 2 4 5% 54%	2280
	21st to end	Night	13% 4 2 5% 3 3 3 3 4 5% 56%	2508
November	1st to 10th	Night	14% 6% 1 5% 3 3 4 3 4 5% 53%	2341
	11th to 20th	Night	13% 6% 2 5% 3 4 4 3 5% 5% 50%	2420
	21st to end	Night	13% 4 2 4 4 3 3 3 4 7% 52%	2750
December	1st to 10th	Night	12% 5% 2 6% 4 4 4 3 4 5% 53%	4580
	11th to 20th	Night	17% 8% 3 7% 5% 4 4 3 4 5% 40%	5090
	21st to end	Night	17% 6% 2 5% 3 3 3 3 5% 7% 47%	6490

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	35% 1 3 21% 31% 8%	4057
	11th to 20th	Day	33% 1 3 18% 36% 8%	4060
	21st to end	Day	42% 2 5% 22% 22% 7%	4466
February	1st to 10th	Day	41% 2 10% 22% 20% 5%	1800
	11th to 20th	Day	45% 2 6% 19% 21% 6%	1767
	21st to end	Day	45% 2 9% 17% 21% 6%	1795
March	1st to 10th	Day	46% 1 6% 18% 17% 11%	4935
	11th to 20th	Day	34% 2 6% 18% 24% 16%	4980
	21st to end	Day	41% 3 8% 21% 21% 6%	5465
April	1st to 10th	Day	31% 3 10% 24% 23% 9%	2326
	11th to 20th	Day	35% 2 11% 23% 22% 7%	2374
	21st to end	Day	39% 3 12% 24% 18% 4	2400
May	1st to 10th	Day	43% 4 19% 22% 11% 2	5884
	11th to 20th	Day	52% 5% 11% 22% 10% 1	5865
	21st to end	Day	39% 3 13% 23% 18% 3	6447
June	1st to 10th	Day	38% 5% 14% 25% 17% 1	2600
	11th to 20th	Day	34% 5% 17% 26% 16% 2	2600
	21st to end	Day	34% 6% 17% 25% 16% 2	2600
July	1st to 10th	Day	39% 8% 18% 19% 13% 3	5835
	11th to 20th	Day	42% 12% 26% 15% 4 1	5831
	21st to end	Day	41% 8% 17% 24% 10%	6240
August	1st to 10th	Day	54% 5% 17% 17% 5%	4143
	11th to 20th	Day	40% 7% 21% 22% 9% 1	3965
	21st to end	Day	30% 4 15% 34% 14% 2	4180
September	1st to 10th	Day	37% 6% 14% 18% 20% 5%	2280
	11th to 20th	Day	42% 4 10% 19% 21% 3	2154
	21st to end	Day	47% 3 9% 20% 17% 4	2047
October	1st to 10th	Day	35% 4 6% 20% 27% 9%	3160
	11th to 20th	Day	21% 1 4 22% 28% 23%	3140
	21st to end	Day	24% 2 7% 26% 25% 15%	3428
November	1st to 10th	Day	35% 2 7% 23% 26% 7%	1957
	11th to 20th	Day	35% 1 8% 23% 26% 7%	1975
	21st to end	Day	35% 3 7% 23% 27% 5%	1644
December	1st to 10th	Day	35% 2 7% 23% 25% 7%	2600
	11th to 20th	Day	42% 3 10% 19% 22% 6%	3078
	21st to end	Day	40% 2 12% 26% 19% 2	4466
January	1st to 10th	Night	34% 1 4 19% 30% 12%	5889
	11th to 20th	Night	34% 1 5% 17% 36% 7%	5900
	21st to end	Night	39% 1 5% 22% 27% 6%	6490
February	1st to 10th	Night	41% 2 10% 23% 20% 5%	2600
	11th to 20th	Night	44% 3 8% 17% 21% 7%	2529
	21st to end	Night	39% 2 8% 22% 21% 8%	1832
March	1st to 10th	Night	46% 1 5% 16% 22% 10%	4918
	11th to 20th	Night	33% 2 6% 16% 25% 18%	4980
	21st to end	Night	37% 3 7% 24% 23% 6%	5467
April	1st to 10th	Night	37% 3 10% 18% 25% 7%	2072
	11th to 20th	Night	35% 2 9% 24% 22% 7%	1975
	21st to end	Night	38% 3 11% 25% 19% 4	2000
May	1st to 10th	Night	45% 4 16% 20% 13% 2	4115
	11th to 20th	Night	51% 4 11% 19% 14% 1	4033
	21st to end	Night	39% 4 13% 26% 16% 2	4429
June	1st to 10th	Night	38% 6% 16% 22% 17% 1	1800
	11th to 20th	Night	37% 6% 17% 22% 15% 3	1800
	21st to end	Night	36% 7% 17% 21% 16% 3	1800
July	1st to 10th	Night	43% 10% 18% 17% 11% 2	4015
	11th to 20th	Night	49% 12% 21% 13% 4 1	4006
	21st to end	Night	45% 8% 16% 22% 10%	4297
August	1st to 10th	Night	53% 6% 18% 16% 6% 1	2850
	11th to 20th	Night	38% 7% 19% 26% 8% 1	2897
	21st to end	Night	31% 5% 11% 30% 20% 2	3476
September	1st to 10th	Night	37% 6% 12% 22% 18% 5%	1900
	11th to 20th	Night	41% 5% 11% 19% 22% 3	2023
	21st to end	Night	48% 5% 10% 17% 16% 4	2133
October	1st to 10th	Night	40% 3 7% 19% 25% 6%	3800
	11th to 20th	Night	26% 1 6% 21% 27% 19%	3779
	21st to end	Night	24% 2 6% 28% 24% 16%	4120
November	1st to 10th	Night	36% 2 7% 21% 27% 7%	2341
	11th to 20th	Night	37% 2 7% 18% 26% 11%	2420
	21st to end	Night	34% 2 7% 24% 27% 7%	2750
December	1st to 10th	Night	36% 2 5% 21% 29% 6%	4580
	11th to 20th	Night	48% 3 7% 18% 16% 8%	5093
	21st to end	Night	39% 1 11% 25% 21% 2	6490

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	28% 24% 34% 11% 4	300
	11th to 20th	Day	28% 25% 32% 13% 3	300
	21st to end	Day	20% 21% 43% 13% 2	330
February	1st to 10th	Day	20% 21% 40% 15% 3	300
	11th to 20th	Day	41% 20% 30% 7% 2	305
	21st to end	Day	26% 18% 34% 19% 4	414
March	1st to 10th	Day	24% 19% 33% 19% 5%	500
	11th to 20th	Day	21% 19% 40% 14% 5% 1	500
	21st to end	Day	23% 17% 38% 17% 5%	550
April	1st to 10th	Day	21% 18% 37% 15% 8% 1	500
	11th to 20th	Day	14% 19% 32% 22% 10% 3	492
	21st to end	Day	19% 8% 31% 29% 12% 1	500
May	1st to 10th	Day	17% 17% 29% 25% 9% 3	503
	11th to 20th	Day	18% 6% 26% 26% 18% 5%	527
	21st to end	Day	18% 5% 20% 28% 20% 8%	573
June	1st to 10th	Day	13% 4 25% 29% 21% 7%	530
	11th to 20th	Day	9% 4 20% 30% 27% 10%	530
	21st to end	Day	10% 3 19% 33% 27% 8%	530
July	1st to 10th	Day	10% 3 11% 31% 34% 11%	525
	11th to 20th	Day	8% 1 10% 28% 38% 15%	524
	21st to end	Day	9% 1 14% 36% 27% 13%	576
August	1st to 10th	Day	15% 5% 17% 28% 24% 12%	502
	11th to 20th	Day	12% 3 12% 29% 29% 14%	479
	21st to end	Day	11% 3 10% 27% 30% 19%	539
September	1st to 10th	Day	13% 3 16% 27% 24% 17%	490
	11th to 20th	Day	17% 4 12% 31% 25% 12%	490
	21st to end	Day	27% 7% 21% 25% 17% 4	490
October	1st to 10th	Day	18% 6% 21% 24% 23% 8%	490
	11th to 20th	Day	15% 9% 24% 28% 18% 5%	490
	21st to end	Day	15% 11% 23% 30% 17% 4	539
November	1st to 10th	Day	17% 9% 32% 25% 14% 4	495
	11th to 20th	Day	19% 14% 28% 25% 11% 1	475
	21st to end	Day	19% 18% 28% 20% 13% 2	222
December	1st to 10th	Day	23% 20% 37% 14% 7% 1	200
	11th to 20th	Day	22% 14% 32% 24% 8% 1	220
	21st to end	Day	25% 17% 33% 16% 8% 2	330
January	1st to 10th	Night	22% 19% 31% 24% 4	800
	11th to 20th	Night	21% 16% 32% 24% 7%	800
	21st to end	Night	20% 15% 37% 24% 4	880
February	1st to 10th	Night	21% 14% 35% 27% 3	800
	11th to 20th	Night	27% 18% 35% 19% 1	783
	21st to end	Night	19% 16% 36% 26% 3	660
March	1st to 10th	Night	18% 15% 33% 28% 5%	800
	11th to 20th	Night	20% 16% 34% 22% 8%	800
	21st to end	Night	18% 13% 42% 23% 5%	880
April	1st to 10th	Night	19% 18% 31% 26% 6%	800
	11th to 20th	Night	15% 13% 35% 26% 11%	791
	21st to end	Night	15% 8% 33% 36% 9%	800
May	1st to 10th	Night	15% 11% 32% 31% 11%	629
	11th to 20th	Night	18% 5% 28% 28% 19% 1	591
	21st to end	Night	15% 3 15% 38% 26% 2	650
June	1st to 10th	Night	12% 3 17% 41% 26% 2	600
	11th to 20th	Night	12% 3 16% 38% 27% 4	600
	21st to end	Night	9% 2 14% 43% 30% 3	600
July	1st to 10th	Night	10% 2 9% 35% 39% 5%	585
	11th to 20th	Night	8% 3 7% 38% 38% 6%	582
	21st to end	Night	7% 3 12% 38% 35% 6%	657
August	1st to 10th	Night	13% 3 9% 36% 34% 4	579
	11th to 20th	Night	12% 2 10% 36% 34% 6%	610
	21st to end	Night	12% 2 9% 33% 38% 7%	836
September	1st to 10th	Night	14% 2 10% 34% 34% 6%	760
	11th to 20th	Night	18% 3 12% 32% 31% 4	760
	21st to end	Night	26% 3 17% 31% 22% 2	760
October	1st to 10th	Night	18% 4 15% 32% 24% 6%	760
	11th to 20th	Night	17% 9% 23% 29% 21% 2	760
	21st to end	Night	15% 10% 24% 30% 20% 2	836
November	1st to 10th	Night	17% 8% 25% 34% 14% 3	780
	11th to 20th	Night	16% 12% 29% 33% 11% 1	800
	21st to end	Night	16% 12% 29% 30% 13% 1	800
December	1st to 10th	Night	22% 13% 29% 30% 8%	800
	11th to 20th	Night	19% 9% 33% 32% 7%	800
	21st to end	Night	23% 13% 24% 33% 7%	880

Page generated at 2025-08-02 01:32:27. Version ac07

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