Fort Lauderdale
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fort Lauderdale 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	7% 6% 3 8% 6% 6% 7% 6% 9% 11% 32%	100559
	Night	6% 6% 2 7% 5% 5% 6% 5% 8% 11% 39%	98389
Transparency	Day	39% 12% 20% 18% 9% 2	104256
	Night	35% 12% 21% 20% 10% 2	102831
Seeing	Day	7% 3 15% 29% 28% 17%	16036
	Night	7% 3 15% 32% 31% 12%	26160

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	10% 8% 3 7% 4 5% 5% 4 7% 9% 37%	2836
	11th to 20th	Day	15% 9% 4 10% 6% 6% 6% 5% 7% 8% 24%	2840
	21st to end	Day	6% 7% 3 10% 7% 6% 7% 5% 7% 8% 35%	3134
February	1st to 10th	Day	9% 7% 3 6% 5% 5% 6% 4 7% 10% 38%	1900
	11th to 20th	Day	7% 5% 2 4 4 4 5% 4 8% 10% 46%	1978
	21st to end	Day	6% 4 2 6% 5% 6% 5% 6% 7% 9% 43%	1727
March	1st to 10th	Day	6% 5% 3 8% 6% 7% 8% 6% 10% 11% 29%	3435
	11th to 20th	Day	4 3 1 5% 4 4 5% 5% 8% 10% 50%	3480
	21st to end	Day	9% 5% 2 5% 5% 4 5% 4 7% 9% 44%	3815
April	1st to 10th	Day	3 4 2 5% 5% 4 6% 6% 9% 13% 42%	2090
	11th to 20th	Day	6% 5% 3 7% 6% 6% 6% 5% 8% 11% 38%	2168
	21st to end	Day	6% 4 3 5% 5% 6% 7% 6% 9% 10% 40%	2280
May	1st to 10th	Day	2 2 1 4 3 3 5% 5% 8% 11% 56%	3765
	11th to 20th	Day	5% 5% 2 7% 6% 6% 6% 6% 11% 12% 34%	3764
	21st to end	Day	5% 5% 2 6% 5% 6% 7% 6% 9% 11% 38%	4472
June	1st to 10th	Day	12% 8% 4 12% 9% 8% 9% 6% 9% 8% 15%	2470
	11th to 20th	Day	7% 6% 4 10% 9% 9% 9% 7% 9% 10% 18%	2470
	21st to end	Day	6% 8% 3 10% 7% 9% 8% 8% 10% 12% 20%	2470
July	1st to 10th	Day	5% 6% 3 7% 6% 6% 7% 7% 10% 15% 29%	4120
	11th to 20th	Day	4 6% 3 7% 6% 6% 8% 7% 12% 14% 26%	4120
	21st to end	Day	3 4 2 7% 6% 6% 7% 7% 11% 16% 30%	4466
August	1st to 10th	Day	4 5% 2 11% 8% 8% 9% 8% 12% 12% 20%	3990
	11th to 20th	Day	4 4 2 7% 6% 7% 9% 8% 12% 16% 26%	3730
	21st to end	Day	5% 4 2 8% 6% 8% 9% 8% 12% 18% 20%	3938
September	1st to 10th	Day	7% 5% 3 10% 8% 9% 10% 8% 10% 11% 19%	2090
	11th to 20th	Day	6% 6% 3 11% 9% 9% 9% 8% 10% 11% 20%	2090
	21st to end	Day	10% 9% 3 11% 7% 8% 10% 6% 8% 9% 18%	2090
October	1st to 10th	Day	9% 6% 4 11% 9% 7% 7% 7% 11% 10% 20%	1986
	11th to 20th	Day	9% 7% 3 8% 7% 7% 8% 6% 10% 11% 24%	1900
	21st to end	Day	11% 7% 3 8% 6% 5% 6% 4 7% 10% 33%	2090
November	1st to 10th	Day	7% 7% 2 7% 6% 6% 5% 6% 9% 10% 35%	1887
	11th to 20th	Day	10% 7% 3 9% 7% 7% 6% 5% 8% 9% 29%	1900
	21st to end	Day	8% 5% 2 9% 7% 6% 7% 6% 8% 8% 36%	1900
December	1st to 10th	Day	8% 5% 2 7% 6% 5% 6% 5% 7% 9% 39%	1891
	11th to 20th	Day	9% 7% 2 7% 7% 5% 5% 4 6% 9% 38%	2153
	21st to end	Day	13% 7% 2 8% 6% 6% 6% 6% 8% 10% 28%	3124
January	1st to 10th	Night	8% 7% 3 7% 6% 6% 6% 5% 7% 10% 36%	4109
	11th to 20th	Night	17% 10% 3 9% 6% 6% 6% 4 5% 8% 27%	4120
	21st to end	Night	6% 8% 4 9% 6% 6% 6% 5% 6% 7% 37%	4518
February	1st to 10th	Night	8% 6% 2 5% 4 4 4 4 7% 10% 44%	2280
	11th to 20th	Night	6% 4 2 4 4 4 4 4 6% 8% 54%	2085
	21st to end	Night	6% 2 2 5% 4 4 5% 4 6% 9% 53%	1727
March	1st to 10th	Night	5% 5% 3 10% 5% 6% 6% 6% 7% 9% 38%	3418
	11th to 20th	Night	4 3 1 4 4 4 4 4 6% 12% 54%	3480
	21st to end	Night	7% 4 1 5% 4 4 3 4 6% 10% 52%	3817
April	1st to 10th	Night	4 3 1 4 3 4 4 4 9% 10% 55%	2090
	11th to 20th	Night	5% 3 2 5% 5% 5% 6% 5% 7% 10% 47%	1957
	21st to end	Night	5% 5% 2 4 4 3 5% 4 7% 10% 49%	1900
May	1st to 10th	Night	2 2 1 3 3 3 4 3 7% 9% 63%	3130
	11th to 20th	Night	4 4 2 6% 4 5% 5% 5% 9% 10% 46%	3130
	21st to end	Night	5% 5% 2 6% 4 4 6% 5% 7% 11% 43%	3095
June	1st to 10th	Night	11% 8% 4 10% 6% 8% 7% 6% 9% 9% 24%	1710
	11th to 20th	Night	7% 6% 3 7% 7% 5% 7% 6% 8% 13% 32%	1710
	21st to end	Night	4 5% 2 7% 7% 6% 7% 7% 10% 13% 30%	1710
July	1st to 10th	Night	4 5% 2 7% 6% 6% 6% 5% 8% 12% 39%	2840
	11th to 20th	Night	4 4 2 7% 5% 5% 7% 6% 10% 14% 36%	2840
	21st to end	Night	2 4 2 6% 5% 5% 6% 6% 8% 14% 42%	3087
August	1st to 10th	Night	4 4 2 7% 6% 6% 8% 7% 10% 13% 33%	2907
	11th to 20th	Night	2 3 2 7% 6% 5% 7% 6% 9% 15% 38%	3097
	21st to end	Night	5% 4 2 7% 5% 6% 8% 8% 13% 18% 23%	3698
September	1st to 10th	Night	5% 6% 3 7% 7% 8% 8% 7% 11% 11% 28%	2090
	11th to 20th	Night	7% 6% 3 9% 7% 7% 7% 7% 9% 12% 27%	2090
	21st to end	Night	8% 8% 3 10% 7% 8% 8% 6% 8% 9% 24%	2090
October	1st to 10th	Night	8% 6% 4 9% 7% 8% 8% 7% 8% 11% 24%	2194
	11th to 20th	Night	8% 7% 3 7% 5% 6% 6% 5% 8% 12% 33%	2280
	21st to end	Night	10% 6% 3 7% 5% 5% 5% 5% 7% 8% 38%	2508
November	1st to 10th	Night	9% 5% 2 6% 5% 5% 6% 4 6% 11% 41%	2264
	11th to 20th	Night	8% 8% 2 8% 7% 6% 6% 5% 6% 8% 35%	2280
	21st to end	Night	8% 7% 2 7% 6% 5% 6% 4 8% 9% 40%	2280
December	1st to 10th	Night	6% 6% 2 6% 5% 5% 5% 5% 8% 9% 43%	2284
	11th to 20th	Night	11% 7% 2 7% 4 4 4 3 6% 8% 43%	3042
	21st to end	Night	9% 9% 3 9% 6% 6% 6% 5% 8% 9% 30%	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	40% 8% 11% 21% 15% 4	2837
	11th to 20th	Day	52% 11% 13% 14% 8% 3	2840
	21st to end	Day	42% 9% 11% 19% 14% 6%	3134
February	1st to 10th	Day	37% 9% 13% 23% 14% 4	1900
	11th to 20th	Day	28% 7% 13% 26% 20% 6%	1988
	21st to end	Day	32% 9% 13% 17% 22% 7%	1727
March	1st to 10th	Day	37% 17% 16% 18% 10% 3	3435
	11th to 20th	Day	22% 11% 20% 34% 10% 2	3480
	21st to end	Day	30% 9% 13% 27% 16% 5%	3815
April	1st to 10th	Day	26% 10% 22% 25% 14% 3	2090
	11th to 20th	Day	35% 10% 18% 20% 15% 3	2168
	21st to end	Day	32% 9% 14% 24% 17% 3	2280
May	1st to 10th	Day	17% 9% 18% 32% 21% 4	3800
	11th to 20th	Day	33% 14% 26% 22% 5%	3768
	21st to end	Day	30% 13% 17% 29% 10%	4485
June	1st to 10th	Day	59% 15% 15% 10% 2	2470
	11th to 20th	Day	52% 18% 16% 12% 1	2470
	21st to end	Day	49% 19% 23% 9%	2470
July	1st to 10th	Day	38% 15% 30% 17%	4055
	11th to 20th	Day	42% 14% 34% 11%	4051
	21st to end	Day	35% 16% 34% 14%	4324
August	1st to 10th	Day	47% 17% 26% 9% 1	3977
	11th to 20th	Day	39% 14% 31% 16% 1	3766
	21st to end	Day	42% 15% 36% 6% 1	3938
September	1st to 10th	Day	48% 22% 19% 10%	2090
	11th to 20th	Day	51% 19% 20% 8% 2	2090
	21st to end	Day	55% 16% 14% 9% 5% 1	2090
October	1st to 10th	Day	50% 12% 19% 13% 5% 1	3298
	11th to 20th	Day	49% 10% 15% 16% 9% 1	3140
	21st to end	Day	39% 6% 11% 27% 15% 3	3428
November	1st to 10th	Day	35% 11% 15% 16% 15% 7%	1887
	11th to 20th	Day	47% 9% 11% 16% 12% 4	1900
	21st to end	Day	39% 9% 15% 16% 18% 3	1900
December	1st to 10th	Day	37% 10% 14% 21% 16% 2	1891
	11th to 20th	Day	38% 8% 12% 18% 17% 6%	2150
	21st to end	Day	44% 10% 15% 16% 13% 2	3124
January	1st to 10th	Night	38% 10% 15% 20% 14% 2	4109
	11th to 20th	Night	53% 9% 14% 15% 7% 2	4120
	21st to end	Night	40% 10% 13% 18% 13% 6%	4518
February	1st to 10th	Night	32% 8% 15% 26% 16% 3	2280
	11th to 20th	Night	24% 7% 13% 28% 21% 7%	2086
	21st to end	Night	25% 8% 13% 23% 24% 6%	1727
March	1st to 10th	Night	35% 13% 16% 19% 13% 3	3418
	11th to 20th	Night	19% 12% 26% 30% 11% 2	3480
	21st to end	Night	24% 9% 16% 25% 22% 4	3817
April	1st to 10th	Night	20% 9% 20% 33% 14% 3	2090
	11th to 20th	Night	27% 10% 20% 22% 19% 2	1957
	21st to end	Night	26% 9% 17% 25% 18% 4	1900
May	1st to 10th	Night	14% 9% 20% 40% 14% 3	3160
	11th to 20th	Night	25% 14% 24% 29% 8%	3131
	21st to end	Night	26% 14% 21% 31% 7%	3103
June	1st to 10th	Night	49% 14% 23% 11% 2	1710
	11th to 20th	Night	39% 17% 25% 16% 3	1710
	21st to end	Night	37% 21% 30% 11% 1	1710
July	1st to 10th	Night	35% 13% 34% 17%	2795
	11th to 20th	Night	34% 14% 42% 11%	2786
	21st to end	Night	30% 16% 38% 15% 1	2988
August	1st to 10th	Night	38% 16% 28% 16% 2	2896
	11th to 20th	Night	31% 15% 33% 21%	3127
	21st to end	Night	39% 18% 37% 6% 1	3698
September	1st to 10th	Night	41% 22% 25% 11% 1	2090
	11th to 20th	Night	44% 20% 23% 11% 2	2090
	21st to end	Night	50% 18% 15% 12% 5%	2090
October	1st to 10th	Night	50% 13% 19% 14% 4 1	3662
	11th to 20th	Night	47% 7% 18% 16% 11% 1	3779
	21st to end	Night	39% 6% 12% 27% 14% 3	4120
November	1st to 10th	Night	34% 7% 18% 19% 16% 6%	2264
	11th to 20th	Night	40% 9% 14% 21% 12% 5%	2280
	21st to end	Night	35% 10% 17% 19% 16% 4	2280
December	1st to 10th	Night	31% 11% 16% 23% 16% 2	2284
	11th to 20th	Night	35% 7% 12% 21% 17% 8%	3044
	21st to end	Night	42% 12% 15% 15% 13% 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	8% 7% 29% 42% 13% 1	270
	11th to 20th	Day	13% 7% 30% 33% 16% 2	270
	21st to end	Day	9% 8% 39% 35% 8% 1	297
February	1st to 10th	Day	7% 10% 26% 39% 17% 2	270
	11th to 20th	Day	6% 6% 24% 39% 20% 4	401
	21st to end	Day	5% 4 21% 40% 29% 1	382
March	1st to 10th	Day	3 6% 32% 40% 17% 3	460
	11th to 20th	Day	5% 5% 25% 40% 22% 2	460
	21st to end	Day	6% 2 26% 39% 24% 4	506
April	1st to 10th	Day	3 3 29% 41% 19% 5%	460
	11th to 20th	Day	6% 3 25% 39% 22% 5%	452
	21st to end	Day	5% 4 16% 44% 26% 5%	460
May	1st to 10th	Day	4 1 12% 41% 32% 10%	463
	11th to 20th	Day	9% 3 14% 34% 29% 11%	487
	21st to end	Day	8% 3 10% 21% 36% 23%	529
June	1st to 10th	Day	10% 3 9% 26% 32% 20%	490
	11th to 20th	Day	9% 2 8% 19% 32% 31%	490
	21st to end	Day	3 2 4 13% 33% 44%	490
July	1st to 10th	Day	4 1 3 12% 36% 45%	485
	11th to 20th	Day	6% 3 13% 38% 39%	484
	21st to end	Day	4 1 3 16% 32% 44%	532
August	1st to 10th	Day	6% 1 6% 14% 34% 39%	486
	11th to 20th	Day	4 1 3 14% 36% 42%	479
	21st to end	Day	8% 1 5% 21% 34% 31%	539
September	1st to 10th	Day	7% 1 4 16% 34% 38%	490
	11th to 20th	Day	5% 2 6% 16% 32% 39%	490
	21st to end	Day	9% 3 7% 22% 32% 27%	490
October	1st to 10th	Day	12% 2 10% 30% 34% 11%	490
	11th to 20th	Day	10% 3 14% 32% 28% 11%	490
	21st to end	Day	9% 5% 19% 32% 28% 7%	539
November	1st to 10th	Day	9% 5% 18% 36% 26% 7%	467
	11th to 20th	Day	10% 5% 24% 32% 24% 5%	460
	21st to end	Day	6% 3 23% 41% 25% 3	460
December	1st to 10th	Day	9% 3 20% 39% 26% 3	451
	11th to 20th	Day	8% 5% 21% 37% 24% 4	270
	21st to end	Day	9% 8% 22% 35% 20% 5%	297
January	1st to 10th	Night	8% 6% 21% 39% 24% 2	760
	11th to 20th	Night	10% 6% 26% 38% 20% 1	760
	21st to end	Night	7% 6% 29% 43% 15%	836
February	1st to 10th	Night	9% 5% 24% 41% 19% 1	760
	11th to 20th	Night	6% 5% 25% 40% 22% 1	743
	21st to end	Night	6% 3 21% 47% 21% 1	628
March	1st to 10th	Night	5% 3 30% 41% 19% 1	760
	11th to 20th	Night	7% 3 21% 46% 22% 2	760
	21st to end	Night	5% 4 23% 44% 21% 2	836
April	1st to 10th	Night	3 3 17% 50% 25% 2	760
	11th to 20th	Night	6% 4 20% 45% 24% 1	751
	21st to end	Night	7% 2 17% 47% 24% 2	760
May	1st to 10th	Night	4 1 12% 46% 35% 3	760
	11th to 20th	Night	8% 1 15% 42% 31% 3	749
	21st to end	Night	8% 2 7% 27% 45% 11%	633
June	1st to 10th	Night	11% 2 5% 23% 43% 16%	570
	11th to 20th	Night	7% 1 3 16% 45% 27%	570
	21st to end	Night	4 1 3 13% 40% 39%	570
July	1st to 10th	Night	5% 1 2 10% 41% 42%	555
	11th to 20th	Night	4 1 3 12% 39% 42%	552
	21st to end	Night	3 1 10% 40% 45%	624
August	1st to 10th	Night	7% 2 11% 45% 33%	610
	11th to 20th	Night	3 1 3 11% 45% 37%	750
	21st to end	Night	9% 1 5% 18% 38% 29%	836
September	1st to 10th	Night	6% 1 5% 14% 40% 33%	760
	11th to 20th	Night	9% 2 5% 16% 39% 29%	760
	21st to end	Night	10% 2 8% 18% 39% 24%	760
October	1st to 10th	Night	10% 1 10% 33% 36% 10%	760
	11th to 20th	Night	11% 3 11% 28% 40% 9%	760
	21st to end	Night	13% 2 16% 35% 28% 6%	836
November	1st to 10th	Night	9% 3 23% 32% 29% 4	755
	11th to 20th	Night	10% 3 19% 33% 31% 4	760
	21st to end	Night	8% 3 20% 42% 25% 3	760
December	1st to 10th	Night	7% 2 18% 39% 31% 3	760
	11th to 20th	Night	9% 6% 19% 33% 29% 4	760
	21st to end	Night	7% 4 21% 37% 28% 2	836

Page generated at 2024-11-01 22:47:48. Version ac07

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