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 2024-11-04.

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%	100625
	Night	15% 6% 2 6% 4 4 4 4 5% 7% 44%	98348
Transparency	Day	39% 4 12% 22% 18% 5%	104274
	Night	40% 3 10% 22% 20% 6%	102838
Seeing	Day	17% 10% 25% 24% 17% 6%	15283
	Night	17% 9% 24% 31% 17% 2	25611

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% 6% 2 5% 2 2 3 2 4 5% 52%	2836
	11th to 20th	Day	14% 6% 2 5% 4 2 3 2 4 5% 51%	2840
	21st to end	Day	19% 10% 2 6% 3 3 3 3 4 4 41%	3124
February	1st to 10th	Day	14% 6% 2 6% 5% 4 4 5% 5% 7% 44%	1710
	11th to 20th	Day	20% 7% 2 5% 4 3 4 3 4 4 45%	1667
	21st to end	Day	19% 8% 3 6% 4 3 4 3 4 6% 41%	1708
March	1st to 10th	Day	23% 7% 2 5% 4 4 4 3 5% 6% 37%	3435
	11th to 20th	Day	10% 5% 2 5% 4 3 3 3 5% 7% 54%	3480
	21st to end	Day	20% 6% 2 5% 5% 3 4 3 4 6% 42%	3815
April	1st to 10th	Day	10% 5% 1 4 3 3 4 3 6% 8% 54%	2209
	11th to 20th	Day	10% 5% 2 6% 5% 4 4 3 5% 7% 49%	2254
	21st to end	Day	15% 5% 1 5% 4 4 4 4 5% 7% 45%	2280
May	1st to 10th	Day	12% 7% 2 8% 5% 6% 6% 4 8% 9% 33%	4069
	11th to 20th	Day	18% 6% 2 7% 5% 5% 5% 4 6% 8% 34%	4081
	21st to end	Day	8% 4 1 5% 4 5% 5% 4 6% 9% 48%	4476
June	1st to 10th	Day	10% 5% 2 6% 5% 5% 5% 5% 6% 10% 41%	2470
	11th to 20th	Day	8% 5% 2 5% 5% 5% 4 4 6% 10% 46%	2470
	21st to end	Day	7% 5% 2 6% 5% 5% 5% 5% 9% 12% 40%	2470
July	1st to 10th	Day	6% 5% 2 7% 5% 6% 7% 6% 9% 11% 36%	4120
	11th to 20th	Day	11% 5% 2 7% 5% 5% 7% 5% 9% 11% 33%	4120
	21st to end	Day	11% 8% 3 8% 7% 6% 7% 5% 7% 9% 29%	4466
August	1st to 10th	Day	19% 8% 2 8% 6% 6% 6% 5% 7% 10% 24%	4104
	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% 3 4 4 3 4 4 55%	1887
	11th to 20th	Day	14% 5% 2 4 3 3 3 3 5% 6% 52%	1877
	21st to end	Day	14% 4 2 5% 4 2 3 3 5% 6% 50%	1562
December	1st to 10th	Day	17% 7% 2 5% 4 4 4 4 6% 5% 41%	1520
	11th to 20th	Day	16% 4 1 5% 2 2 2 2 4 5% 56%	1974
	21st to end	Day	18% 5% 1 5% 4 4 4 4 6% 7% 43%	3124
January	1st to 10th	Night	15% 6% 2 5% 3 3 4 3 5% 6% 47%	4109
	11th to 20th	Night	15% 7% 2 5% 4 3 3 3 5% 5% 47%	4120
	21st to end	Night	20% 7% 2 5% 3 3 3 3 4 5% 45%	4532
February	1st to 10th	Night	17% 6% 2 5% 3 4 4 4 4 6% 46%	2470
	11th to 20th	Night	19% 8% 2 4 4 3 3 4 5% 5% 43%	2398
	21st to end	Night	15% 7% 1 6% 4 3 4 3 5% 6% 45%	1744
March	1st to 10th	Night	23% 8% 3 7% 4 5% 4 4 4 5% 36%	3418
	11th to 20th	Night	13% 6% 2 5% 4 3 3 3 4 6% 52%	3480
	21st to end	Night	17% 5% 2 4 3 3 3 4 4 6% 49%	3817
April	1st to 10th	Night	14% 5% 2 4 4 4 4 4 4 7% 49%	1969
	11th to 20th	Night	12% 5% 2 4 4 4 4 3 5% 6% 50%	1875
	21st to end	Night	12% 5% 2 6% 4 4 4 4 6% 6% 47%	1900
May	1st to 10th	Night	14% 7% 2 7% 5% 4 4 4 6% 7% 39%	2854
	11th to 20th	Night	21% 8% 2 7% 4 4 3 3 5% 6% 36%	2812
	21st to end	Night	9% 5% 1 5% 4 4 4 4 7% 10% 48%	3079
June	1st to 10th	Night	10% 5% 2 6% 4 4 5% 5% 8% 9% 41%	1710
	11th to 20th	Night	9% 6% 2 5% 5% 5% 5% 4 7% 10% 42%	1710
	21st to end	Night	7% 5% 3 6% 5% 6% 6% 4 7% 12% 41%	1710
July	1st to 10th	Night	8% 6% 3 7% 5% 5% 6% 5% 8% 12% 35%	2840
	11th to 20th	Night	13% 6% 3 6% 5% 5% 6% 4 7% 10% 34%	2840
	21st to end	Night	14% 10% 3 9% 6% 5% 5% 4 5% 9% 30%	3087
August	1st to 10th	Night	21% 7% 3 6% 4 5% 6% 5% 8% 11% 23%	2825
	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 3 2 3 5% 54%	2264
	11th to 20th	Night	13% 6% 2 5% 3 4 4 3 5% 5% 51%	2299
	21st to end	Night	14% 4 2 4 4 3 3 3 4 7% 51%	2612
December	1st to 10th	Night	18% 6% 3 6% 5% 4 4 3 4 5% 42%	2660
	11th to 20th	Night	17% 6% 3 4 4 3 3 3 4 5% 49%	3212
	21st to end	Night	18% 7% 2 5% 3 3 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	49% 2 7% 20% 14% 8%	3435
	11th to 20th	Day	33% 2 7% 21% 24% 13%	3480
	21st to end	Day	46% 2 8% 20% 20% 4	3815
April	1st to 10th	Day	30% 3 10% 24% 23% 10%	2209
	11th to 20th	Day	36% 2 11% 22% 23% 7%	2254
	21st to end	Day	39% 2 11% 25% 18% 4	2280
May	1st to 10th	Day	47% 3 16% 20% 12% 2	4107
	11th to 20th	Day	49% 3 10% 26% 11% 1	4085
	21st to end	Day	33% 3 16% 24% 20% 4	4489
June	1st to 10th	Day	38% 5% 15% 25% 17% 1	2470
	11th to 20th	Day	34% 5% 17% 27% 16% 2	2470
	21st to end	Day	35% 6% 17% 25% 16% 2	2470
July	1st to 10th	Day	38% 9% 18% 19% 13% 3	4055
	11th to 20th	Day	43% 7% 23% 20% 6% 1	4051
	21st to end	Day	49% 7% 14% 18% 11%	4324
August	1st to 10th	Day	54% 5% 17% 18% 5%	4091
	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	34% 2 7% 23% 27% 7%	1887
	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	54% 2 6% 17% 17% 5%	3418
	11th to 20th	Night	36% 2 6% 15% 24% 16%	3480
	21st to end	Night	38% 2 7% 24% 22% 6%	3817
April	1st to 10th	Night	37% 3 10% 18% 25% 7%	1969
	11th to 20th	Night	35% 2 9% 24% 22% 8%	1875
	21st to end	Night	38% 3 10% 25% 19% 5%	1900
May	1st to 10th	Night	45% 3 16% 21% 13% 2	2881
	11th to 20th	Night	50% 2 8% 22% 16% 1	2813
	21st to end	Night	32% 3 16% 27% 18% 2	3087
June	1st to 10th	Night	37% 6% 16% 23% 16% 1	1710
	11th to 20th	Night	37% 5% 16% 23% 16% 3	1710
	21st to end	Night	36% 7% 17% 21% 16% 3	1710
July	1st to 10th	Night	40% 11% 18% 18% 12% 2	2795
	11th to 20th	Night	45% 8% 23% 18% 5% 2	2786
	21st to end	Night	53% 7% 13% 18% 10%	2988
August	1st to 10th	Night	53% 6% 18% 16% 6% 1	2814
	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 6% 21% 27% 8%	2264
	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	21% 17% 37% 15% 9% 1	460
	11th to 20th	Day	14% 19% 30% 22% 11% 3	452
	21st to end	Day	20% 8% 31% 27% 12% 1	460
May	1st to 10th	Day	18% 17% 28% 24% 10% 3	463
	11th to 20th	Day	17% 6% 25% 28% 19% 5%	487
	21st to end	Day	16% 4 19% 30% 22% 8%	529
June	1st to 10th	Day	13% 4 25% 30% 22% 8%	490
	11th to 20th	Day	10% 5% 19% 30% 27% 10%	490
	21st to end	Day	10% 3 20% 33% 26% 7%	490
July	1st to 10th	Day	10% 2 11% 30% 35% 12%	485
	11th to 20th	Day	8% 1 10% 29% 38% 14%	484
	21st to end	Day	10% 1 14% 36% 27% 11%	532
August	1st to 10th	Day	14% 5% 17% 27% 25% 12%	486
	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% 30% 25% 14% 4	467
	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	18% 17% 32% 26% 7%	760
	11th to 20th	Night	15% 13% 33% 26% 12%	751
	21st to end	Night	15% 8% 32% 36% 8%	760
May	1st to 10th	Night	15% 11% 31% 32% 11%	598
	11th to 20th	Night	18% 5% 27% 29% 20% 1	561
	21st to end	Night	14% 2 15% 39% 28% 2	617
June	1st to 10th	Night	12% 2 16% 41% 26% 2	570
	11th to 20th	Night	12% 3 15% 38% 27% 4	570
	21st to end	Night	10% 2 14% 43% 28% 3	570
July	1st to 10th	Night	10% 2 10% 35% 39% 5%	555
	11th to 20th	Night	8% 3 7% 38% 39% 5%	552
	21st to end	Night	7% 3 12% 39% 34% 5%	624
August	1st to 10th	Night	13% 3 10% 36% 35% 4	567
	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	755
	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 2024-11-01 22:47:50. Version ac07

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