St. Sebastian River Preserve State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the St. Sebastian River Preserve State Park clear sky chart from 2005-11-06 to 2025-04-11.

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
Cloud Cover	Day	7% 5% 2 7% 6% 6% 6% 5% 8% 10% 37%	113674
	Night	8% 6% 2 7% 5% 5% 5% 4 7% 9% 42%	114621
Transparency	Day	36% 11% 18% 20% 12% 3	117385
	Night	35% 9% 18% 21% 13% 4	119049
Seeing	Day	8% 4 16% 27% 27% 19%	16367
	Night	9% 3 14% 30% 31% 12%	26541

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	7% 5% 2 6% 4 4 4 4 5% 8% 51%	4056
	11th to 20th	Day	15% 9% 4 9% 5% 5% 5% 5% 5% 8% 30%	4060
	21st to end	Day	15% 7% 2 6% 5% 4 5% 4 7% 7% 37%	4466
February	1st to 10th	Day	10% 6% 2 7% 5% 4 5% 4 6% 9% 43%	1985
	11th to 20th	Day	8% 4 2 5% 4 5% 5% 4 6% 8% 50%	2001
	21st to end	Day	9% 5% 2 5% 4 5% 5% 5% 7% 7% 48%	1815
March	1st to 10th	Day	6% 5% 2 8% 6% 6% 6% 4 7% 8% 42%	4935
	11th to 20th	Day	3 3 1 4 3 3 4 4 5% 9% 61%	4980
	21st to end	Day	8% 5% 2 7% 5% 5% 5% 5% 6% 8% 44%	5465
April	1st to 10th	Day	5% 4 2 6% 5% 5% 5% 4 8% 8% 48%	2200
	11th to 20th	Day	8% 5% 3 7% 4 5% 6% 6% 8% 10% 37%	2168
	21st to end	Day	5% 4 2 5% 5% 5% 6% 7% 7% 9% 45%	2280
May	1st to 10th	Day	3 2 1 3 3 4 5% 4 6% 11% 58%	3765
	11th to 20th	Day	7% 5% 3 7% 6% 7% 6% 6% 8% 11% 35%	4037
	21st to end	Day	5% 3 2 5% 5% 5% 5% 4 8% 9% 49%	4476
June	1st to 10th	Day	11% 8% 4 10% 7% 8% 7% 6% 9% 11% 21%	2470
	11th to 20th	Day	6% 6% 3 9% 7% 7% 7% 7% 9% 12% 26%	2470
	21st to end	Day	7% 8% 3 9% 7% 8% 8% 6% 9% 11% 25%	2470
July	1st to 10th	Day	6% 6% 2 8% 6% 7% 8% 7% 9% 12% 30%	4120
	11th to 20th	Day	5% 6% 2 8% 7% 6% 8% 7% 11% 14% 27%	4120
	21st to end	Day	5% 6% 2 9% 8% 8% 8% 6% 10% 12% 26%	4466
August	1st to 10th	Day	3 5% 2 9% 8% 8% 9% 7% 11% 15% 23%	4104
	11th to 20th	Day	4 3 2 6% 6% 7% 9% 6% 10% 13% 33%	3773
	21st to end	Day	5% 5% 2 8% 7% 7% 9% 7% 11% 15% 23%	3939
September	1st to 10th	Day	6% 4 4 10% 8% 9% 9% 7% 9% 10% 22%	2090
	11th to 20th	Day	9% 6% 3 8% 7% 9% 9% 7% 9% 10% 23%	2090
	21st to end	Day	9% 6% 3 9% 8% 8% 8% 6% 8% 9% 26%	2090
October	1st to 10th	Day	12% 6% 3 9% 6% 5% 7% 5% 8% 9% 29%	2001
	11th to 20th	Day	7% 7% 3 6% 5% 6% 6% 6% 8% 10% 37%	1900
	21st to end	Day	8% 5% 2 6% 5% 5% 5% 4 6% 10% 43%	2090
November	1st to 10th	Day	9% 5% 2 7% 6% 6% 7% 5% 7% 8% 38%	1957
	11th to 20th	Day	9% 7% 2 8% 6% 6% 6% 5% 6% 9% 35%	2000
	21st to end	Day	8% 7% 2 8% 6% 5% 5% 5% 7% 9% 39%	2000
December	1st to 10th	Day	6% 5% 2 5% 4 4 5% 4 6% 8% 53%	2996
	11th to 20th	Day	9% 6% 2 8% 5% 6% 8% 5% 7% 11% 32%	3373
	21st to end	Day	10% 7% 3 9% 6% 7% 7% 5% 7% 8% 32%	4466
January	1st to 10th	Night	7% 4 2 6% 4 4 5% 4 6% 9% 50%	5889
	11th to 20th	Night	14% 11% 4 9% 5% 5% 5% 4 6% 7% 30%	5900
	21st to end	Night	14% 7% 2 7% 5% 4 4 4 6% 7% 41%	6490
February	1st to 10th	Night	10% 6% 2 6% 4 4 4 3 6% 7% 47%	2410
	11th to 20th	Night	8% 5% 1 5% 4 4 5% 3 6% 8% 51%	2283
	21st to end	Night	8% 4 2 4 4 4 4 4 7% 8% 53%	1815
March	1st to 10th	Night	6% 5% 2 7% 5% 5% 5% 4 6% 8% 47%	4918
	11th to 20th	Night	4 3 1 3 3 3 4 4 7% 11% 58%	4980
	21st to end	Night	7% 5% 2 6% 5% 5% 4 4 7% 8% 47%	5467
April	1st to 10th	Night	5% 3 1 5% 4 4 5% 4 6% 8% 56%	2200
	11th to 20th	Night	5% 5% 2 5% 5% 5% 5% 4 7% 10% 48%	1968
	21st to end	Night	6% 4 2 6% 5% 5% 4 4 6% 8% 51%	1900
May	1st to 10th	Night	4 3 1 3 3 3 3 3 6% 8% 62%	3130
	11th to 20th	Night	8% 4 2 5% 4 5% 6% 5% 7% 11% 44%	2883
	21st to end	Night	4 4 2 5% 4 4 5% 4 7% 9% 52%	3079
June	1st to 10th	Night	10% 7% 3 8% 6% 5% 6% 6% 8% 11% 28%	1710
	11th to 20th	Night	6% 8% 2 6% 6% 6% 8% 7% 9% 12% 30%	1710
	21st to end	Night	6% 6% 3 8% 6% 5% 5% 6% 10% 11% 33%	1710
July	1st to 10th	Night	6% 5% 2 7% 5% 4 5% 5% 8% 13% 40%	2840
	11th to 20th	Night	4 6% 2 6% 5% 5% 6% 7% 9% 14% 37%	2840
	21st to end	Night	3 5% 3 8% 7% 7% 7% 6% 9% 13% 34%	3087
August	1st to 10th	Night	3 5% 3 9% 6% 6% 6% 5% 8% 13% 35%	2825
	11th to 20th	Night	4 4 2 7% 5% 7% 7% 6% 8% 12% 40%	3024
	21st to end	Night	6% 6% 2 7% 6% 7% 6% 6% 10% 14% 29%	3697
September	1st to 10th	Night	7% 6% 3 8% 7% 7% 7% 7% 10% 12% 26%	2090
	11th to 20th	Night	8% 8% 3 10% 7% 6% 6% 5% 7% 11% 28%	2090
	21st to end	Night	9% 8% 3 10% 6% 6% 7% 5% 8% 10% 28%	2090
October	1st to 10th	Night	11% 7% 4 8% 5% 6% 6% 4 8% 9% 33%	2176
	11th to 20th	Night	7% 6% 2 6% 5% 5% 5% 5% 7% 9% 42%	2280
	21st to end	Night	9% 6% 2 6% 4 4 4 4 7% 9% 44%	2508
November	1st to 10th	Night	7% 6% 2 7% 6% 6% 6% 4 7% 8% 40%	2341
	11th to 20th	Night	8% 7% 3 7% 5% 5% 5% 5% 7% 8% 42%	2400
	21st to end	Night	10% 6% 2 6% 5% 5% 5% 5% 7% 10% 40%	2400
December	1st to 10th	Night	5% 3 2 5% 4 3 4 4 6% 8% 55%	4179
	11th to 20th	Night	12% 8% 3 8% 5% 5% 5% 4 7% 8% 36%	4822
	21st to end	Night	10% 8% 3 9% 6% 5% 5% 4 7% 8% 35%	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	32% 5% 9% 21% 28% 5%	4057
	11th to 20th	Day	50% 6% 10% 19% 12% 2	4060
	21st to end	Day	42% 7% 7% 26% 14% 4	4466
February	1st to 10th	Day	35% 6% 12% 19% 20% 7%	1985
	11th to 20th	Day	27% 7% 12% 26% 20% 8%	2011
	21st to end	Day	30% 6% 13% 19% 25% 7%	1815
March	1st to 10th	Day	35% 10% 12% 18% 21% 4	4935
	11th to 20th	Day	19% 5% 13% 30% 18% 14%	4980
	21st to end	Day	33% 8% 12% 27% 15% 6%	5465
April	1st to 10th	Day	27% 9% 17% 25% 18% 4	2200
	11th to 20th	Day	34% 11% 14% 20% 17% 4	2168
	21st to end	Day	30% 8% 14% 21% 23% 4	2280
May	1st to 10th	Day	15% 8% 19% 37% 16% 4	3800
	11th to 20th	Day	37% 13% 21% 19% 10%	4041
	21st to end	Day	25% 9% 17% 35% 14%	4489
June	1st to 10th	Day	50% 11% 21% 14% 3	2470
	11th to 20th	Day	42% 15% 22% 19% 2	2470
	21st to end	Day	44% 14% 26% 12% 3	2470
July	1st to 10th	Day	35% 16% 30% 15% 3	4055
	11th to 20th	Day	37% 14% 39% 9%	4051
	21st to end	Day	40% 18% 28% 14%	4324
August	1st to 10th	Day	39% 19% 32% 9% 1	4091
	11th to 20th	Day	31% 16% 31% 15% 8%	3810
	21st to end	Day	39% 18% 32% 9% 2	3939
September	1st to 10th	Day	46% 18% 22% 12% 2	2090
	11th to 20th	Day	45% 18% 22% 12% 3	2090
	21st to end	Day	47% 15% 16% 13% 9% 1	2090
October	1st to 10th	Day	50% 12% 19% 12% 6% 2	3326
	11th to 20th	Day	31% 8% 12% 24% 22% 3	3140
	21st to end	Day	28% 6% 13% 26% 23% 4	3428
November	1st to 10th	Day	38% 8% 13% 17% 18% 6%	1957
	11th to 20th	Day	42% 7% 11% 20% 14% 6%	2000
	21st to end	Day	38% 8% 12% 21% 15% 6%	2000
December	1st to 10th	Day	27% 7% 20% 25% 13% 8%	2996
	11th to 20th	Day	43% 7% 13% 17% 15% 4	3370
	21st to end	Day	44% 9% 13% 19% 12% 4	4466
January	1st to 10th	Night	30% 6% 11% 24% 22% 7%	5889
	11th to 20th	Night	51% 5% 12% 19% 10% 3	5900
	21st to end	Night	42% 6% 9% 23% 13% 6%	6490
February	1st to 10th	Night	35% 6% 13% 20% 18% 8%	2410
	11th to 20th	Night	29% 6% 12% 24% 22% 8%	2284
	21st to end	Night	28% 6% 15% 22% 24% 7%	1815
March	1st to 10th	Night	34% 8% 12% 22% 20% 5%	4918
	11th to 20th	Night	18% 8% 18% 28% 17% 12%	4980
	21st to end	Night	31% 7% 13% 26% 19% 4	5467
April	1st to 10th	Night	24% 7% 20% 27% 17% 6%	2200
	11th to 20th	Night	29% 10% 15% 24% 20% 3	1968
	21st to end	Night	28% 8% 14% 22% 23% 5%	1900
May	1st to 10th	Night	17% 9% 18% 36% 15% 4	3160
	11th to 20th	Night	30% 12% 23% 28% 8% 1	2884
	21st to end	Night	24% 11% 17% 36% 12%	3087
June	1st to 10th	Night	46% 11% 23% 16% 4	1710
	11th to 20th	Night	41% 14% 23% 19% 3	1710
	21st to end	Night	39% 14% 27% 16% 3	1710
July	1st to 10th	Night	33% 13% 30% 21% 2	2795
	11th to 20th	Night	32% 17% 41% 9%	2786
	21st to end	Night	37% 17% 30% 14% 1	2988
August	1st to 10th	Night	38% 14% 35% 11% 2	2814
	11th to 20th	Night	31% 13% 33% 13% 9%	3053
	21st to end	Night	39% 17% 33% 10% 1	3697
September	1st to 10th	Night	44% 19% 22% 13% 2	2090
	11th to 20th	Night	47% 14% 22% 14% 2	2090
	21st to end	Night	47% 13% 16% 14% 9% 1	2090
October	1st to 10th	Night	56% 11% 14% 11% 7% 2	3631
	11th to 20th	Night	33% 8% 12% 26% 18% 2	3779
	21st to end	Night	32% 7% 10% 23% 22% 5%	4120
November	1st to 10th	Night	39% 8% 13% 17% 17% 7%	2341
	11th to 20th	Night	38% 8% 12% 23% 13% 6%	2400
	21st to end	Night	38% 7% 13% 18% 18% 5%	2400
December	1st to 10th	Night	27% 6% 18% 32% 12% 6%	4179
	11th to 20th	Night	41% 8% 16% 15% 14% 6%	4824
	21st to end	Night	43% 8% 15% 18% 11% 5%	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	9% 7% 38% 31% 14% 1	300
	11th to 20th	Day	9% 11% 31% 31% 14% 5%	300
	21st to end	Day	17% 8% 38% 29% 8%	330
February	1st to 10th	Day	10% 5% 27% 34% 20% 4	300
	11th to 20th	Day	8% 5% 29% 36% 17% 5%	353
	21st to end	Day	7% 3 30% 34% 21% 4	414
March	1st to 10th	Day	4 7% 32% 40% 15% 2	500
	11th to 20th	Day	7% 4 29% 36% 20% 4	500
	21st to end	Day	4 6% 30% 32% 22% 5%	550
April	1st to 10th	Day	5% 4 32% 36% 18% 5%	500
	11th to 20th	Day	7% 5% 26% 37% 20% 6%	452
	21st to end	Day	7% 3 17% 39% 25% 10%	460
May	1st to 10th	Day	4 2 15% 39% 28% 12%	463
	11th to 20th	Day	9% 3 12% 33% 29% 14%	487
	21st to end	Day	9% 2 6% 25% 35% 22%	529
June	1st to 10th	Day	12% 2 6% 25% 29% 25%	490
	11th to 20th	Day	7% 4 5% 18% 31% 35%	490
	21st to end	Day	7% 2 2 13% 33% 44%	490
July	1st to 10th	Day	6% 1 1 11% 35% 47%	485
	11th to 20th	Day	6% 2 1 8% 37% 47%	484
	21st to end	Day	8% 1 2 14% 30% 44%	532
August	1st to 10th	Day	5% 2 2 12% 35% 44%	486
	11th to 20th	Day	4 1 1 7% 35% 52%	479
	21st to end	Day	8% 1 4 17% 32% 38%	539
September	1st to 10th	Day	6% 3 4 14% 32% 40%	490
	11th to 20th	Day	9% 2 5% 19% 34% 32%	490
	21st to end	Day	8% 2 6% 22% 35% 27%	490
October	1st to 10th	Day	15% 3 9% 30% 31% 12%	490
	11th to 20th	Day	9% 2 14% 34% 30% 11%	490
	21st to end	Day	6% 3 17% 36% 29% 8%	539
November	1st to 10th	Day	11% 5% 16% 35% 25% 8%	495
	11th to 20th	Day	12% 5% 21% 33% 25% 4	500
	21st to end	Day	7% 4 20% 38% 25% 6%	500
December	1st to 10th	Day	6% 5% 25% 37% 21% 6%	340
	11th to 20th	Day	9% 6% 24% 37% 20% 4	300
	21st to end	Day	11% 5% 27% 34% 18% 5%	330
January	1st to 10th	Night	12% 7% 24% 36% 19% 2	800
	11th to 20th	Night	11% 5% 28% 36% 19% 2	800
	21st to end	Night	11% 7% 29% 39% 14%	880
February	1st to 10th	Night	12% 6% 21% 40% 20% 2	800
	11th to 20th	Night	9% 5% 25% 41% 19% 2	783
	21st to end	Night	10% 2 21% 46% 20%	660
March	1st to 10th	Night	6% 6% 29% 44% 14% 1	800
	11th to 20th	Night	7% 4 23% 42% 22% 3	800
	21st to end	Night	6% 4 26% 40% 22% 1	880
April	1st to 10th	Night	6% 3 23% 45% 22% 2	800
	11th to 20th	Night	6% 4 20% 44% 24% 2	754
	21st to end	Night	7% 3 16% 46% 26% 4	760
May	1st to 10th	Night	6% 1 12% 47% 30% 3	760
	11th to 20th	Night	9% 2 10% 37% 33% 9%	606
	21st to end	Night	7% 2 5% 23% 47% 15%	617
June	1st to 10th	Night	12% 1 4 23% 48% 12%	570
	11th to 20th	Night	8% 2 4 15% 47% 25%	570
	21st to end	Night	6% 2 3 11% 46% 32%	570
July	1st to 10th	Night	8% 3 1 8% 45% 34%	555
	11th to 20th	Night	8% 1 1 7% 37% 46%	552
	21st to end	Night	5% 2 1 6% 47% 39%	624
August	1st to 10th	Night	4 2 3 8% 46% 37%	567
	11th to 20th	Night	5% 1 1 7% 47% 38%	701
	21st to end	Night	11% 1 3 13% 43% 29%	836
September	1st to 10th	Night	7% 3 4 11% 46% 29%	760
	11th to 20th	Night	11% 2 4 15% 44% 24%	760
	21st to end	Night	13% 3 4 19% 40% 22%	760
October	1st to 10th	Night	15% 2 7% 31% 35% 10%	760
	11th to 20th	Night	9% 3 10% 30% 39% 9%	760
	21st to end	Night	12% 3 14% 32% 33% 7%	836
November	1st to 10th	Night	10% 3 19% 31% 32% 6%	780
	11th to 20th	Night	10% 4 20% 36% 27% 4	800
	21st to end	Night	12% 5% 16% 40% 25% 3	800
December	1st to 10th	Night	8% 4 19% 39% 27% 3	800
	11th to 20th	Night	11% 5% 19% 36% 25% 5%	800
	21st to end	Night	8% 5% 21% 38% 26% 2	880

Page generated at 2025-04-08 09:17:27. Version ac07

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