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 2024-04-03.

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% 5% 2 5% 5% 3 5% 5% 5% 7% 44%	78757
	Night	14% 5% 2 5% 5% 3 4 4 5% 7% 45%	81370
Transparency	Day	40% 3 11% 23% 19% 4	78478
	Night	40% 3 10% 22% 20% 5%	81168
Seeing	Day	18% 10% 25% 24% 17% 6%	14423
	Night	17% 9% 24% 31% 17% 2	24857

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	18% 5% 2 4 3 2 3 3 3 5% 52%	2836
	11th to 20th	Day	14% 6% 3 5% 4 2 3 3 4 5% 51%	2840
	21st to end	Day	19% 10% 3 5% 4 2 4 4 5% 4 41%	3124
February	1st to 10th	Day	14% 5% 2 5% 5% 3 5% 5% 5% 7% 44%	1710
	11th to 20th	Day	20% 6% 2 4 4 2 4 3 3 5% 45%	1667
	21st to end	Day	19% 7% 3 6% 5% 3 4 4 4 6% 41%	1708
March	1st to 10th	Day	16% 4 2 3 4 3 4 4 5% 6% 49%	2090
	11th to 20th	Day	14% 6% 3 6% 5% 2 4 4 5% 8% 43%	2090
	21st to end	Day	17% 7% 3 5% 6% 3 5% 4 4 7% 40%	2299
April	1st to 10th	Day	11% 4 1 3 4 2 3 3 5% 8% 54%	2114
	11th to 20th	Day	11% 5% 2 5% 5% 3 4 4 5% 8% 49%	2134
	21st to end	Day	15% 5% 2 4 4 3 4 4 5% 7% 45%	2160
May	1st to 10th	Day	12% 5% 2 4 6% 3 5% 5% 7% 9% 41%	2327
	11th to 20th	Day	16% 4 2 5% 5% 4 6% 6% 6% 8% 38%	2301
	21st to end	Day	12% 6% 2 5% 5% 4 7% 6% 6% 8% 39%	2531
June	1st to 10th	Day	10% 5% 2 5% 6% 3 6% 6% 6% 10% 41%	2340
	11th to 20th	Day	8% 5% 3 4 5% 3 5% 5% 6% 10% 46%	2340
	21st to end	Day	8% 4 3 5% 5% 4 6% 6% 8% 12% 39%	2340
July	1st to 10th	Day	8% 5% 2 5% 6% 5% 7% 8% 7% 11% 36%	2340
	11th to 20th	Day	8% 4 2 6% 6% 4 7% 8% 9% 12% 35%	2340
	21st to end	Day	7% 4 2 6% 7% 4 8% 7% 8% 11% 35%	2547
August	1st to 10th	Day	11% 6% 2 6% 7% 5% 7% 7% 7% 10% 33%	2327
	11th to 20th	Day	11% 7% 3 6% 6% 4 7% 7% 8% 8% 32%	2241
	21st to end	Day	11% 6% 2 6% 7% 3 6% 6% 7% 9% 37%	2376
September	1st to 10th	Day	10% 5% 2 5% 6% 3 4 5% 6% 8% 45%	2160
	11th to 20th	Day	14% 5% 3 5% 5% 3 5% 5% 4 7% 43%	2041
	21st to end	Day	22% 6% 3 4 4 3 3 4 5% 7% 39%	1940
October	1st to 10th	Day	16% 5% 2 5% 4 2 4 3 4 6% 50%	1800
	11th to 20th	Day	14% 4 2 3 4 2 3 4 4 5% 55%	1800
	21st to end	Day	12% 4 1 4 4 3 3 3 3 5% 56%	1980
November	1st to 10th	Day	13% 4 2 4 4 2 4 3 3 4 56%	1857
	11th to 20th	Day	14% 5% 2 4 3 2 3 3 5% 6% 52%	1877
	21st to end	Day	14% 4 2 4 4 2 3 4 5% 7% 50%	1562
December	1st to 10th	Day	17% 7% 3 5% 4 3 4 5% 6% 5% 41%	1520
	11th to 20th	Day	16% 4 1 4 3 2 2 3 4 5% 57%	1974
	21st to end	Day	18% 5% 2 5% 4 2 4 4 5% 8% 43%	3124
January	1st to 10th	Night	15% 6% 2 4 5% 2 4 4 5% 6% 47%	4109
	11th to 20th	Night	15% 7% 2 5% 4 2 4 4 4 5% 48%	4120
	21st to end	Night	20% 6% 2 4 4 2 4 3 4 5% 45%	4532
February	1st to 10th	Night	17% 6% 2 5% 3 2 4 5% 4 7% 46%	2470
	11th to 20th	Night	19% 7% 2 3 4 3 4 4 4 5% 43%	2398
	21st to end	Night	15% 6% 2 5% 5% 3 4 4 5% 6% 45%	1744
March	1st to 10th	Night	14% 4 2 5% 4 3 4 4 4 5% 51%	2090
	11th to 20th	Night	16% 6% 3 5% 5% 3 4 4 5% 7% 43%	2090
	21st to end	Night	16% 5% 3 5% 4 2 4 5% 4 8% 44%	2299
April	1st to 10th	Night	15% 5% 2 4 4 2 4 4 4 7% 49%	1889
	11th to 20th	Night	13% 4 3 4 4 3 4 3 5% 7% 50%	1775
	21st to end	Night	13% 4 2 5% 5% 3 5% 4 5% 7% 47%	1800
May	1st to 10th	Night	11% 5% 2 4 5% 3 5% 5% 6% 8% 45%	1647
	11th to 20th	Night	16% 6% 2 5% 5% 3 4 4 6% 8% 39%	1592
	21st to end	Night	12% 6% 2 4 6% 4 4 4 6% 9% 43%	1744
June	1st to 10th	Night	10% 4 2 5% 5% 3 6% 6% 8% 10% 42%	1620
	11th to 20th	Night	10% 5% 3 5% 5% 3 6% 5% 7% 10% 41%	1620
	21st to end	Night	8% 4 3 6% 5% 4 6% 6% 7% 12% 40%	1620
July	1st to 10th	Night	8% 6% 2 4 6% 4 5% 7% 7% 12% 40%	1620
	11th to 20th	Night	6% 4 3 5% 6% 4 6% 7% 8% 12% 39%	1620
	21st to end	Night	6% 4 2 6% 7% 4 6% 7% 6% 12% 39%	1771
August	1st to 10th	Night	10% 6% 4 6% 6% 4 6% 7% 8% 11% 33%	1611
	11th to 20th	Night	10% 6% 3 6% 7% 4 5% 8% 7% 9% 36%	1641
	21st to end	Night	11% 5% 2 6% 5% 4 6% 6% 6% 10% 39%	1980
September	1st to 10th	Night	12% 5% 2 5% 5% 3 3 5% 5% 7% 48%	1800
	11th to 20th	Night	14% 5% 2 5% 5% 3 4 5% 5% 7% 45%	1916
	21st to end	Night	22% 6% 2 5% 4 3 4 5% 6% 6% 37%	2020
October	1st to 10th	Night	16% 6% 2 4 5% 2 3 4 4 6% 48%	2160
	11th to 20th	Night	14% 6% 2 4 4 2 3 3 4 5% 53%	2160
	21st to end	Night	13% 4 2 4 3 3 4 4 4 5% 54%	2376
November	1st to 10th	Night	14% 6% 2 4 4 2 3 3 3 5% 54%	2221
	11th to 20th	Night	13% 5% 2 5% 4 2 4 4 5% 6% 51%	2299
	21st to end	Night	14% 4 2 3 4 3 4 4 4 7% 52%	2612
December	1st to 10th	Night	18% 6% 3 5% 5% 3 4 4 4 6% 42%	2660
	11th to 20th	Night	17% 6% 3 4 4 2 3 4 4 5% 49%	3212
	21st to end	Night	18% 6% 2 4 4 2 3 3 5% 7% 45%	4532

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	38% 1 4 27% 23% 6%	2837
	11th to 20th	Day	38% 1 5% 20% 31% 5%	2840
	21st to end	Day	48% 2 5% 18% 21% 6%	3124
February	1st to 10th	Day	41% 2 10% 22% 21% 5%	1710
	11th to 20th	Day	44% 2 6% 20% 22% 7%	1676
	21st to end	Day	47% 2 10% 16% 20% 6%	1708
March	1st to 10th	Day	37% 3 8% 24% 23% 7%	2090
	11th to 20th	Day	42% 3 9% 21% 18% 8%	2090
	21st to end	Day	46% 3 9% 19% 18% 4	2299
April	1st to 10th	Day	30% 3 10% 25% 23% 10%	2114
	11th to 20th	Day	36% 2 11% 22% 22% 7%	2134
	21st to end	Day	39% 2 11% 24% 19% 5%	2160
May	1st to 10th	Day	40% 3 16% 21% 17% 4	2327
	11th to 20th	Day	44% 4 14% 24% 12% 2	2305
	21st to end	Day	42% 4 15% 25% 13% 1	2531
June	1st to 10th	Day	38% 5% 15% 24% 17% 1	2340
	11th to 20th	Day	34% 5% 17% 26% 16% 2	2340
	21st to end	Day	37% 6% 17% 24% 15% 2	2340
July	1st to 10th	Day	40% 6% 16% 20% 14% 3	2275
	11th to 20th	Day	38% 7% 21% 22% 11% 2	2271
	21st to end	Day	40% 5% 19% 25% 10%	2405
August	1st to 10th	Day	44% 6% 16% 23% 10% 1	2314
	11th to 20th	Day	46% 6% 16% 20% 11% 1	2241
	21st to end	Day	43% 5% 17% 21% 11% 3	2376
September	1st to 10th	Day	37% 6% 15% 19% 18% 6%	2160
	11th to 20th	Day	41% 4 10% 20% 22% 4	2041
	21st to end	Day	46% 3 9% 21% 18% 4	1940
October	1st to 10th	Day	38% 3 8% 24% 24% 4	1800
	11th to 20th	Day	33% 2 7% 29% 22% 7%	1800
	21st to end	Day	33% 2 7% 25% 25% 8%	1980
November	1st to 10th	Day	34% 2 7% 23% 27% 7%	1857
	11th to 20th	Day	35% 1 8% 23% 26% 7%	1877
	21st to end	Day	35% 3 7% 23% 26% 6%	1562
December	1st to 10th	Day	44% 3 10% 21% 18% 4	1520
	11th to 20th	Day	32% 2 7% 27% 24% 9%	1970
	21st to end	Day	42% 1 11% 25% 20% 2	3124
January	1st to 10th	Night	40% 1 5% 22% 26% 6%	4109
	11th to 20th	Night	41% 2 7% 19% 26% 6%	4120
	21st to end	Night	45% 1 4 22% 21% 7%	4532
February	1st to 10th	Night	40% 2 9% 23% 21% 5%	2470
	11th to 20th	Night	44% 2 7% 18% 21% 8%	2400
	21st to end	Night	41% 2 8% 22% 20% 7%	1744
March	1st to 10th	Night	37% 2 7% 23% 23% 7%	2090
	11th to 20th	Night	43% 3 8% 20% 19% 7%	2090
	21st to end	Night	40% 3 9% 22% 19% 5%	2299
April	1st to 10th	Night	37% 3 9% 18% 25% 7%	1889
	11th to 20th	Night	35% 2 9% 23% 22% 8%	1775
	21st to end	Night	38% 3 10% 25% 20% 5%	1800
May	1st to 10th	Night	37% 4 14% 25% 17% 4	1647
	11th to 20th	Night	43% 4 13% 23% 15% 2	1593
	21st to end	Night	38% 5% 15% 27% 14% 1	1745
June	1st to 10th	Night	37% 6% 17% 23% 16% 1	1620
	11th to 20th	Night	38% 5% 17% 22% 15% 3	1620
	21st to end	Night	37% 7% 17% 20% 16% 3	1620
July	1st to 10th	Night	37% 7% 18% 22% 13% 3	1575
	11th to 20th	Night	35% 8% 21% 24% 9% 3	1566
	21st to end	Night	38% 7% 20% 24% 12%	1672
August	1st to 10th	Night	43% 7% 18% 20% 11% 1	1600
	11th to 20th	Night	43% 6% 17% 21% 11% 2	1641
	21st to end	Night	40% 5% 17% 25% 9% 3	1980
September	1st to 10th	Night	37% 6% 13% 22% 17% 5%	1800
	11th to 20th	Night	39% 5% 11% 20% 22% 3	1916
	21st to end	Night	47% 5% 10% 17% 17% 4	2020
October	1st to 10th	Night	40% 3 8% 22% 24% 4	2160
	11th to 20th	Night	36% 2 7% 25% 23% 8%	2160
	21st to end	Night	34% 2 6% 23% 26% 10%	2376
November	1st to 10th	Night	37% 2 6% 20% 28% 8%	2221
	11th to 20th	Night	36% 2 7% 18% 25% 11%	2299
	21st to end	Night	35% 2 7% 23% 27% 7%	2612
December	1st to 10th	Night	46% 2 7% 21% 19% 4	2660
	11th to 20th	Night	40% 2 7% 21% 22% 9%	3215
	21st to end	Night	41% 1 6% 26% 23% 2	4532

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	26% 22% 36% 12% 4	270
	11th to 20th	Day	29% 23% 33% 12% 3	270
	21st to end	Day	22% 20% 42% 13% 3	297
February	1st to 10th	Day	21% 20% 40% 16% 4	270
	11th to 20th	Day	39% 20% 31% 7% 2	274
	21st to end	Day	27% 18% 34% 18% 4	382
March	1st to 10th	Day	23% 18% 33% 19% 6%	460
	11th to 20th	Day	21% 19% 41% 12% 5% 1	460
	21st to end	Day	23% 16% 38% 17% 6%	506
April	1st to 10th	Day	20% 16% 37% 15% 10% 1	428
	11th to 20th	Day	14% 19% 30% 22% 12% 4	412
	21st to end	Day	21% 9% 31% 26% 12% 1	420
May	1st to 10th	Day	18% 17% 28% 24% 9% 3	423
	11th to 20th	Day	17% 6% 25% 28% 20% 5%	447
	21st to end	Day	18% 4 18% 30% 22% 8%	485
June	1st to 10th	Day	13% 4 23% 29% 23% 8%	450
	11th to 20th	Day	10% 5% 19% 29% 26% 11%	450
	21st to end	Day	11% 3 20% 33% 25% 7%	450
July	1st to 10th	Day	10% 2 11% 31% 34% 12%	445
	11th to 20th	Day	7% 1 10% 28% 39% 14%	444
	21st to end	Day	10% 1 14% 36% 27% 12%	488
August	1st to 10th	Day	13% 4 16% 28% 26% 13%	446
	11th to 20th	Day	13% 3 10% 27% 31% 15%	439
	21st to end	Day	12% 3 11% 26% 29% 19%	495
September	1st to 10th	Day	13% 3 15% 27% 25% 18%	450
	11th to 20th	Day	14% 4 12% 32% 25% 13%	450
	21st to end	Day	26% 6% 20% 25% 18% 5%	450
October	1st to 10th	Day	19% 6% 21% 23% 23% 8%	450
	11th to 20th	Day	16% 8% 25% 26% 19% 5%	450
	21st to end	Day	16% 12% 24% 30% 15% 3	495
November	1st to 10th	Day	17% 9% 30% 25% 15% 4	455
	11th to 20th	Day	20% 14% 27% 26% 12% 1	437
	21st to end	Day	19% 16% 29% 21% 14% 2	200
December	1st to 10th	Day	22% 18% 38% 14% 7% 1	180
	11th to 20th	Day	22% 14% 30% 25% 8% 1	198
	21st to end	Day	25% 17% 33% 15% 9% 2	297
January	1st to 10th	Night	22% 18% 30% 25% 4	760
	11th to 20th	Night	21% 15% 32% 25% 7%	760
	21st to end	Night	20% 15% 36% 25% 4	836
February	1st to 10th	Night	20% 14% 34% 29% 3	760
	11th to 20th	Night	26% 18% 36% 19% 1	743
	21st to end	Night	19% 16% 36% 26% 4	628
March	1st to 10th	Night	19% 14% 34% 28% 6%	760
	11th to 20th	Night	20% 16% 33% 22% 8%	760
	21st to end	Night	18% 12% 41% 23% 5%	836
April	1st to 10th	Night	19% 16% 31% 27% 7%	729
	11th to 20th	Night	15% 13% 33% 26% 12%	711
	21st to end	Night	16% 8% 31% 36% 9%	720
May	1st to 10th	Night	15% 11% 31% 32% 11%	567
	11th to 20th	Night	18% 5% 27% 29% 20% 1	531
	21st to end	Night	15% 2 13% 39% 28% 2	584
June	1st to 10th	Night	12% 2 16% 42% 26% 2	540
	11th to 20th	Night	13% 3 16% 37% 27% 5%	540
	21st to end	Night	10% 2 13% 43% 29% 3	540
July	1st to 10th	Night	9% 2 10% 35% 39% 5%	525
	11th to 20th	Night	8% 2 7% 38% 39% 5%	522
	21st to end	Night	7% 2 12% 39% 35% 5%	591
August	1st to 10th	Night	12% 3 9% 36% 36% 4	537
	11th to 20th	Night	13% 2 9% 35% 35% 7%	577
	21st to end	Night	12% 2 9% 33% 37% 7%	792
September	1st to 10th	Night	14% 2 9% 33% 35% 7%	720
	11th to 20th	Night	17% 3 12% 33% 32% 4	720
	21st to end	Night	25% 3 17% 31% 22% 2	720
October	1st to 10th	Night	18% 4 15% 31% 24% 6%	720
	11th to 20th	Night	18% 8% 22% 28% 22% 2	720
	21st to end	Night	15% 11% 25% 30% 18% 2	792
November	1st to 10th	Night	17% 8% 25% 34% 14% 3	740
	11th to 20th	Night	16% 11% 28% 33% 11% 1	760
	21st to end	Night	16% 11% 28% 31% 13% 1	760
December	1st to 10th	Night	22% 12% 28% 30% 8%	760
	11th to 20th	Night	19% 9% 33% 32% 7%	760
	21st to end	Night	24% 13% 24% 32% 7%	836

Page generated at 2024-03-31 06:08:53. Version ac07

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