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 2024-02-25.

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	8% 5% 3 7% 7% 5% 7% 7% 8% 10% 35%	78822
	Night	8% 6% 3 6% 6% 4 6% 6% 7% 9% 40%	80481
Transparency	Day	39% 11% 17% 18% 12% 3	78545
	Night	37% 10% 17% 20% 12% 4	80277
Seeing	Day	8% 3 15% 27% 27% 20%	14800
	Night	9% 3 14% 30% 32% 12%	24989

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	9% 7% 4 7% 6% 4 5% 5% 5% 6% 41%	2836
	11th to 20th	Day	15% 9% 4 7% 5% 3 5% 5% 5% 9% 31%	2840
	21st to end	Day	9% 7% 3 7% 7% 4 6% 6% 7% 7% 38%	3124
February	1st to 10th	Day	11% 6% 3 6% 5% 3 5% 5% 6% 9% 42%	1885
	11th to 20th	Day	8% 3 2 4 5% 3 5% 5% 6% 8% 51%	1898
	21st to end	Day	9% 4 2 4 5% 3 5% 6% 6% 8% 47%	1672
March	1st to 10th	Day	4 4 2 6% 5% 4 5% 6% 6% 9% 49%	1980
	11th to 20th	Day	7% 3 2 5% 5% 4 5% 7% 5% 9% 48%	1980
	21st to end	Day	7% 4 2 4 6% 3 5% 6% 6% 9% 49%	2178
April	1st to 10th	Day	5% 3 2 5% 5% 4 6% 6% 8% 9% 47%	1980
	11th to 20th	Day	8% 5% 3 6% 6% 4 7% 8% 8% 10% 35%	2052
	21st to end	Day	6% 4 2 4 5% 4 7% 8% 6% 10% 44%	2160
May	1st to 10th	Day	5% 2 1 3 4 4 6% 6% 7% 10% 52%	2160
	11th to 20th	Day	9% 5% 3 7% 6% 5% 7% 7% 7% 10% 35%	2271
	21st to end	Day	8% 5% 3 7% 8% 5% 7% 7% 8% 9% 31%	2531
June	1st to 10th	Day	11% 8% 4 8% 9% 6% 8% 7% 8% 11% 20%	2340
	11th to 20th	Day	7% 5% 3 7% 8% 6% 8% 8% 9% 12% 27%	2340
	21st to end	Day	7% 7% 4 7% 7% 6% 9% 8% 9% 11% 25%	2340
July	1st to 10th	Day	8% 6% 2 7% 7% 5% 10% 10% 10% 11% 24%	2340
	11th to 20th	Day	8% 6% 3 8% 8% 5% 8% 8% 11% 13% 23%	2340
	21st to end	Day	7% 6% 3 8% 10% 5% 9% 8% 9% 11% 24%	2547
August	1st to 10th	Day	5% 4 2 7% 8% 5% 8% 9% 11% 14% 26%	2327
	11th to 20th	Day	6% 4 3 6% 8% 6% 9% 10% 10% 13% 25%	2156
	21st to end	Day	8% 6% 4 9% 9% 6% 8% 8% 9% 11% 23%	2247
September	1st to 10th	Day	6% 3 4 8% 9% 7% 9% 10% 9% 11% 23%	1980
	11th to 20th	Day	9% 6% 3 7% 8% 6% 9% 8% 9% 10% 23%	1980
	21st to end	Day	9% 6% 3 8% 9% 6% 8% 8% 8% 9% 26%	1980
October	1st to 10th	Day	10% 6% 3 7% 8% 4 7% 7% 8% 10% 30%	1896
	11th to 20th	Day	7% 7% 3 6% 6% 5% 6% 7% 7% 10% 36%	1800
	21st to end	Day	8% 4 3 5% 6% 3 5% 5% 6% 11% 42%	1980
November	1st to 10th	Day	9% 5% 2 6% 6% 4 8% 6% 7% 8% 39%	1857
	11th to 20th	Day	9% 7% 3 7% 8% 5% 7% 6% 6% 9% 35%	1900
	21st to end	Day	8% 6% 3 7% 6% 4 6% 6% 7% 10% 37%	1900
December	1st to 10th	Day	8% 5% 3 6% 5% 5% 5% 6% 7% 8% 41%	1748
	11th to 20th	Day	11% 6% 2 6% 6% 4 5% 6% 5% 8% 40%	2153
	21st to end	Day	11% 7% 3 7% 8% 5% 8% 6% 7% 7% 31%	3124
January	1st to 10th	Night	10% 6% 3 7% 6% 3 6% 6% 6% 9% 40%	4109
	11th to 20th	Night	16% 12% 5% 8% 5% 3 5% 4 5% 7% 30%	4120
	21st to end	Night	9% 7% 3 6% 7% 4 5% 5% 7% 7% 41%	4532
February	1st to 10th	Night	11% 6% 3 5% 4 3 4 4 6% 8% 47%	2290
	11th to 20th	Night	8% 4 1 4 4 3 5% 5% 6% 8% 52%	2166
	21st to end	Night	8% 3 2 3 4 2 5% 4 7% 8% 54%	1679
March	1st to 10th	Night	4 3 2 4 5% 3 4 4 5% 8% 58%	1980
	11th to 20th	Night	6% 4 1 4 4 2 4 4 6% 11% 54%	1980
	21st to end	Night	6% 3 2 4 5% 3 4 6% 6% 8% 53%	2178
April	1st to 10th	Night	5% 3 1 4 4 3 5% 5% 5% 8% 58%	1980
	11th to 20th	Night	5% 4 3 4 5% 3 6% 5% 7% 10% 47%	1857
	21st to end	Night	6% 4 2 5% 6% 4 5% 5% 6% 9% 50%	1800
May	1st to 10th	Night	6% 3 1 3 3 3 4 5% 6% 9% 59%	1800
	11th to 20th	Night	8% 4 3 5% 5% 4 5% 6% 6% 11% 43%	1635
	21st to end	Night	6% 5% 3 6% 5% 4 5% 8% 9% 11% 38%	1744
June	1st to 10th	Night	10% 7% 4 7% 7% 4 6% 8% 8% 12% 27%	1620
	11th to 20th	Night	6% 6% 2 6% 7% 4 8% 8% 9% 13% 31%	1620
	21st to end	Night	7% 5% 3 7% 6% 4 6% 6% 10% 12% 34%	1620
July	1st to 10th	Night	8% 6% 3 8% 7% 4 6% 8% 9% 11% 31%	1620
	11th to 20th	Night	5% 6% 2 5% 6% 3 7% 9% 9% 11% 35%	1620
	21st to end	Night	4 4 3 6% 7% 4 7% 7% 9% 13% 37%	1771
August	1st to 10th	Night	4 5% 3 6% 6% 3 7% 8% 9% 14% 36%	1611
	11th to 20th	Night	4 3 2 6% 6% 5% 8% 8% 9% 12% 35%	1727
	21st to end	Night	9% 7% 3 7% 7% 5% 6% 9% 8% 12% 28%	2103
September	1st to 10th	Night	7% 5% 3 6% 8% 5% 8% 8% 10% 13% 27%	1980
	11th to 20th	Night	8% 8% 3 8% 8% 4 6% 6% 7% 11% 29%	1980
	21st to end	Night	10% 8% 3 9% 7% 5% 7% 7% 7% 11% 27%	1980
October	1st to 10th	Night	9% 7% 3 7% 6% 4 6% 6% 8% 9% 35%	2061
	11th to 20th	Night	7% 6% 3 5% 6% 4 5% 6% 6% 9% 43%	2160
	21st to end	Night	9% 6% 2 5% 5% 3 5% 5% 7% 9% 44%	2376
November	1st to 10th	Night	8% 5% 3 6% 6% 4 7% 5% 7% 9% 40%	2221
	11th to 20th	Night	8% 6% 4 6% 5% 4 6% 6% 7% 8% 42%	2280
	21st to end	Night	10% 5% 2 6% 6% 4 6% 6% 7% 10% 39%	2280
December	1st to 10th	Night	6% 4 3 6% 7% 4 6% 5% 6% 9% 45%	2427
	11th to 20th	Night	13% 7% 3 6% 5% 3 4 4 6% 8% 41%	3042
	21st to end	Night	10% 8% 4 8% 7% 4 6% 5% 7% 8% 34%	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	43% 7% 7% 16% 23% 5%	2837
	11th to 20th	Day	48% 6% 8% 21% 13% 3	2840
	21st to end	Day	42% 8% 8% 19% 17% 6%	3124
February	1st to 10th	Day	36% 6% 11% 20% 20% 7%	1885
	11th to 20th	Day	27% 7% 12% 25% 20% 8%	1908
	21st to end	Day	31% 6% 13% 18% 26% 7%	1672
March	1st to 10th	Day	29% 7% 13% 23% 23% 5%	1980
	11th to 20th	Day	28% 7% 16% 28% 15% 6%	1980
	21st to end	Day	29% 8% 13% 24% 19% 7%	2178
April	1st to 10th	Day	28% 9% 19% 24% 17% 4	1980
	11th to 20th	Day	36% 11% 14% 19% 16% 4	2052
	21st to end	Day	30% 7% 14% 21% 23% 5%	2160
May	1st to 10th	Day	23% 8% 16% 23% 22% 7%	2160
	11th to 20th	Day	39% 10% 16% 21% 13% 1	2275
	21st to end	Day	42% 11% 16% 19% 12% 1	2531
June	1st to 10th	Day	52% 11% 21% 13% 3	2340
	11th to 20th	Day	41% 15% 23% 19% 2	2340
	21st to end	Day	44% 14% 26% 12% 3	2340
July	1st to 10th	Day	43% 19% 28% 10% 1	2275
	11th to 20th	Day	43% 17% 29% 11% 1	2271
	21st to end	Day	44% 17% 24% 15% 1	2405
August	1st to 10th	Day	36% 19% 33% 11% 1	2314
	11th to 20th	Day	38% 19% 33% 9% 1	2156
	21st to end	Day	46% 17% 26% 9% 3	2247
September	1st to 10th	Day	44% 18% 22% 13% 2	1980
	11th to 20th	Day	45% 18% 23% 12% 3	1980
	21st to end	Day	47% 15% 16% 13% 9% 1	1980
October	1st to 10th	Day	42% 13% 14% 18% 10% 4	1896
	11th to 20th	Day	39% 8% 13% 20% 17% 2	1800
	21st to end	Day	34% 6% 15% 18% 20% 7%	1980
November	1st to 10th	Day	38% 7% 13% 17% 18% 7%	1857
	11th to 20th	Day	43% 7% 10% 20% 14% 6%	1900
	21st to end	Day	39% 8% 12% 21% 15% 5%	1900
December	1st to 10th	Day	37% 8% 15% 23% 14% 4	1748
	11th to 20th	Day	41% 6% 12% 17% 18% 7%	2150
	21st to end	Day	46% 9% 12% 16% 12% 5%	3124
January	1st to 10th	Night	40% 7% 11% 22% 16% 4	4109
	11th to 20th	Night	53% 6% 8% 20% 10% 3	4120
	21st to end	Night	41% 7% 10% 20% 14% 8%	4532
February	1st to 10th	Night	35% 6% 13% 21% 18% 8%	2290
	11th to 20th	Night	28% 5% 13% 24% 22% 8%	2167
	21st to end	Night	28% 6% 15% 21% 24% 7%	1679
March	1st to 10th	Night	25% 5% 13% 29% 22% 6%	1980
	11th to 20th	Night	25% 7% 15% 30% 16% 6%	1980
	21st to end	Night	26% 7% 15% 25% 20% 7%	2178
April	1st to 10th	Night	24% 7% 21% 27% 16% 6%	1980
	11th to 20th	Night	30% 10% 16% 23% 19% 3	1857
	21st to end	Night	29% 8% 14% 23% 22% 5%	1800
May	1st to 10th	Night	22% 8% 13% 28% 21% 8%	1800
	11th to 20th	Night	33% 11% 20% 23% 11% 1	1636
	21st to end	Night	34% 14% 17% 21% 14%	1745
June	1st to 10th	Night	48% 12% 21% 15% 4	1620
	11th to 20th	Night	39% 14% 23% 20% 3	1620
	21st to end	Night	38% 15% 27% 17% 3	1620
July	1st to 10th	Night	42% 17% 27% 13% 1	1575
	11th to 20th	Night	36% 20% 30% 13% 1	1566
	21st to end	Night	33% 20% 31% 14% 1	1672
August	1st to 10th	Night	33% 15% 37% 14%	1600
	11th to 20th	Night	35% 17% 35% 12% 1	1727
	21st to end	Night	43% 18% 25% 12% 2	2103
September	1st to 10th	Night	42% 19% 23% 14% 2	1980
	11th to 20th	Night	46% 14% 23% 14% 2	1980
	21st to end	Night	48% 13% 16% 13% 8% 1	1980
October	1st to 10th	Night	42% 11% 15% 18% 11% 3	2061
	11th to 20th	Night	37% 8% 14% 21% 18% 2	2160
	21st to end	Night	35% 8% 13% 18% 20% 7%	2376
November	1st to 10th	Night	39% 8% 13% 16% 17% 7%	2221
	11th to 20th	Night	38% 8% 12% 23% 13% 6%	2280
	21st to end	Night	39% 8% 14% 19% 17% 4	2280
December	1st to 10th	Night	35% 6% 15% 28% 11% 4	2427
	11th to 20th	Night	41% 5% 13% 18% 14% 9%	3044
	21st to end	Night	45% 8% 14% 16% 13% 5%	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	10% 6% 36% 32% 15% 1	270
	11th to 20th	Day	8% 8% 31% 33% 16% 5%	270
	21st to end	Day	15% 9% 38% 29% 8%	297
February	1st to 10th	Day	11% 6% 29% 35% 18% 2	270
	11th to 20th	Day	8% 4 28% 37% 18% 5%	320
	21st to end	Day	7% 4 28% 33% 23% 4	362
March	1st to 10th	Day	4 5% 31% 40% 17% 3	420
	11th to 20th	Day	8% 4 27% 36% 22% 4	420
	21st to end	Day	4 6% 27% 34% 24% 6%	462
April	1st to 10th	Day	5% 3 31% 35% 20% 5%	420
	11th to 20th	Day	8% 5% 23% 37% 21% 6%	412
	21st to end	Day	8% 2 17% 39% 24% 10%	420
May	1st to 10th	Day	4 2 15% 40% 28% 12%	423
	11th to 20th	Day	9% 2 11% 32% 31% 15%	447
	21st to end	Day	10% 3 6% 23% 34% 24%	485
June	1st to 10th	Day	13% 2 6% 24% 29% 26%	450
	11th to 20th	Day	6% 2 3 18% 33% 38%	450
	21st to end	Day	6% 1 2 13% 32% 45%	450
July	1st to 10th	Day	6% 1 1 8% 35% 49%	445
	11th to 20th	Day	6% 2 7% 38% 47%	444
	21st to end	Day	8% 1 2 14% 30% 45%	488
August	1st to 10th	Day	5% 2 1 10% 36% 47%	446
	11th to 20th	Day	4 1 1 6% 34% 53%	439
	21st to end	Day	9% 2 4 16% 32% 38%	495
September	1st to 10th	Day	6% 2 4 14% 33% 42%	450
	11th to 20th	Day	9% 1 4 18% 34% 34%	450
	21st to end	Day	8% 1 4 22% 37% 28%	450
October	1st to 10th	Day	13% 3 9% 32% 31% 12%	450
	11th to 20th	Day	9% 2 12% 34% 30% 12%	450
	21st to end	Day	7% 2 16% 36% 31% 9%	495
November	1st to 10th	Day	11% 5% 16% 34% 26% 8%	455
	11th to 20th	Day	12% 5% 21% 33% 24% 4	460
	21st to end	Day	7% 4 19% 39% 25% 5%	460
December	1st to 10th	Day	6% 4 22% 38% 23% 6%	308
	11th to 20th	Day	9% 6% 23% 36% 21% 5%	270
	21st to end	Day	10% 5% 25% 35% 19% 5%	297
January	1st to 10th	Night	13% 7% 22% 36% 20% 2	760
	11th to 20th	Night	11% 5% 26% 37% 19% 2	760
	21st to end	Night	10% 7% 29% 40% 14%	836
February	1st to 10th	Night	13% 6% 22% 40% 19% 1	760
	11th to 20th	Night	9% 5% 25% 41% 18% 2	743
	21st to end	Night	10% 3 21% 45% 21%	611
March	1st to 10th	Night	6% 5% 28% 45% 15% 1	720
	11th to 20th	Night	7% 3 22% 41% 23% 3	720
	21st to end	Night	7% 3 25% 40% 24% 2	792
April	1st to 10th	Night	6% 3 21% 45% 23% 2	720
	11th to 20th	Night	6% 4 20% 44% 24% 2	711
	21st to end	Night	7% 3 15% 46% 26% 4	720
May	1st to 10th	Night	6% 1 13% 47% 30% 3	720
	11th to 20th	Night	9% 1 9% 36% 35% 9%	574
	21st to end	Night	8% 1 5% 23% 47% 16%	584
June	1st to 10th	Night	13% 1 4 22% 47% 13%	540
	11th to 20th	Night	8% 2 3 13% 49% 26%	540
	21st to end	Night	6% 1 3 10% 46% 33%	540
July	1st to 10th	Night	9% 3 1 7% 45% 35%	525
	11th to 20th	Night	8% 1 1 6% 38% 46%	522
	21st to end	Night	5% 2 1 6% 47% 40%	591
August	1st to 10th	Night	4 2 2 7% 47% 38%	537
	11th to 20th	Night	5% 1 2 7% 47% 39%	663
	21st to end	Night	11% 1 3 12% 42% 30%	792
September	1st to 10th	Night	7% 3 3 10% 46% 31%	720
	11th to 20th	Night	11% 2 3 15% 44% 25%	720
	21st to end	Night	13% 3 4 18% 40% 22%	720
October	1st to 10th	Night	14% 2 7% 32% 35% 10%	720
	11th to 20th	Night	9% 2 9% 29% 41% 9%	720
	21st to end	Night	12% 2 13% 31% 34% 8%	792
November	1st to 10th	Night	10% 3 19% 30% 32% 6%	740
	11th to 20th	Night	10% 3 19% 36% 27% 4	760
	21st to end	Night	11% 5% 16% 40% 25% 3	760
December	1st to 10th	Night	8% 3 18% 38% 28% 3	760
	11th to 20th	Night	12% 5% 19% 35% 25% 5%	760
	21st to end	Night	8% 5% 20% 38% 27% 3	836

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