Alafia River State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Alafia River State Park clear sky chart from 2005-11-06 to 2025-07-21.

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% 5% 6% 5% 7% 9% 41%	120244
	Night	8% 6% 2 7% 5% 5% 5% 4 7% 9% 43%	118900
Transparency	Day	36% 9% 16% 20% 14% 5%	124034
	Night	35% 9% 16% 20% 14% 5%	123247
Seeing	Day	8% 5% 17% 26% 25% 20%	16468
	Night	9% 4 18% 34% 27% 8%	26526

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% 3 4 4 4 5% 8% 51%	4056
	11th to 20th	Day	18% 9% 4 7% 5% 4 5% 4 6% 7% 31%	4060
	21st to end	Day	13% 5% 2 6% 3 3 3 4 6% 8% 46%	4806
February	1st to 10th	Day	11% 6% 2 5% 5% 4 5% 4 6% 8% 45%	2000
	11th to 20th	Day	7% 5% 1 5% 4 4 4 3 5% 7% 55%	1948
	21st to end	Day	8% 5% 2 5% 4 4 4 4 5% 8% 50%	1730
March	1st to 10th	Day	7% 5% 2 7% 5% 5% 5% 4 5% 8% 47%	4935
	11th to 20th	Day	4 3 1 4 3 3 3 2 5% 9% 60%	4980
	21st to end	Day	7% 4 2 5% 4 4 4 4 6% 8% 51%	5465
April	1st to 10th	Day	6% 4 2 4 5% 5% 6% 5% 6% 9% 50%	2200
	11th to 20th	Day	7% 4 2 6% 5% 4 6% 4 7% 7% 48%	2176
	21st to end	Day	5% 4 1 4 4 4 4 5% 6% 9% 54%	2380
May	1st to 10th	Day	2 3 1 4 4 5% 5% 5% 8% 11% 51%	5834
	11th to 20th	Day	7% 4 2 5% 4 4 4 4 6% 9% 49%	5861
	21st to end	Day	4 3 2 5% 5% 5% 6% 5% 8% 11% 46%	6433
June	1st to 10th	Day	12% 9% 3 9% 6% 6% 7% 5% 7% 11% 25%	2600
	11th to 20th	Day	6% 7% 3 8% 9% 8% 9% 6% 9% 10% 26%	2600
	21st to end	Day	7% 6% 3 9% 8% 8% 7% 6% 9% 11% 26%	2600
July	1st to 10th	Day	7% 6% 3 9% 8% 8% 9% 7% 9% 13% 22%	4250
	11th to 20th	Day	5% 5% 3 10% 8% 9% 9% 7% 10% 12% 24%	4250
	21st to end	Day	6% 6% 3 10% 8% 8% 9% 6% 9% 12% 23%	4466
August	1st to 10th	Day	5% 6% 4 10% 8% 7% 8% 5% 8% 12% 27%	4104
	11th to 20th	Day	3 5% 2 9% 7% 7% 7% 6% 9% 11% 34%	3708
	21st to end	Day	7% 6% 3 9% 7% 8% 8% 6% 9% 13% 23%	3828
September	1st to 10th	Day	7% 7% 2 9% 7% 9% 9% 6% 8% 12% 23%	2090
	11th to 20th	Day	9% 7% 3 11% 9% 6% 8% 6% 9% 9% 23%	2090
	21st to end	Day	8% 8% 3 9% 7% 7% 7% 5% 7% 9% 31%	2090
October	1st to 10th	Day	9% 6% 4 8% 6% 6% 6% 5% 7% 8% 34%	2090
	11th to 20th	Day	7% 5% 2 6% 5% 6% 6% 4 6% 8% 47%	1923
	21st to end	Day	7% 4 2 6% 4 4 4 5% 7% 8% 48%	2090
November	1st to 10th	Day	7% 4 1 6% 4 4 5% 4 6% 8% 50%	1957
	11th to 20th	Day	8% 6% 2 7% 5% 5% 4 4 5% 7% 47%	2000
	21st to end	Day	8% 5% 2 6% 5% 5% 5% 4 5% 8% 47%	1875
December	1st to 10th	Day	4 3 1 4 3 4 4 3 5% 8% 60%	2930
	11th to 20th	Day	9% 6% 2 6% 4 4 5% 3 6% 7% 47%	3373
	21st to end	Day	10% 7% 3 8% 6% 6% 5% 4 5% 8% 38%	4466
January	1st to 10th	Night	7% 5% 3 6% 4 4 4 4 6% 8% 49%	5889
	11th to 20th	Night	20% 11% 4 8% 5% 4 4 3 5% 7% 29%	5900
	21st to end	Night	15% 6% 2 6% 4 4 4 4 6% 8% 41%	6147
February	1st to 10th	Night	10% 7% 3 6% 4 4 5% 4 5% 8% 45%	2400
	11th to 20th	Night	9% 6% 2 5% 3 4 4 3 5% 7% 51%	2338
	21st to end	Night	7% 6% 2 5% 4 5% 4 3 6% 7% 51%	1899
March	1st to 10th	Night	9% 6% 2 6% 4 4 4 4 6% 7% 46%	4918
	11th to 20th	Night	4 3 1 4 3 3 4 3 6% 9% 59%	4980
	21st to end	Night	8% 5% 2 7% 4 4 4 3 5% 6% 51%	5467
April	1st to 10th	Night	6% 4 2 5% 3 4 4 3 7% 10% 53%	2200
	11th to 20th	Night	5% 4 2 5% 3 3 5% 4 7% 10% 51%	2173
	21st to end	Night	5% 4 1 5% 4 3 4 4 5% 7% 58%	2019
May	1st to 10th	Night	4 4 2 6% 4 5% 5% 4 7% 8% 52%	4089
	11th to 20th	Night	7% 5% 2 4 3 3 4 4 6% 8% 53%	4032
	21st to end	Night	5% 4 1 5% 4 4 4 4 7% 10% 54%	4421
June	1st to 10th	Night	10% 8% 2 6% 4 4 5% 6% 8% 10% 36%	1800
	11th to 20th	Night	6% 6% 2 9% 6% 5% 6% 6% 8% 12% 34%	1800
	21st to end	Night	5% 7% 2 8% 6% 6% 6% 6% 9% 12% 33%	1800
July	1st to 10th	Night	7% 7% 3 11% 7% 7% 7% 6% 8% 11% 27%	2930
	11th to 20th	Night	5% 5% 3 9% 7% 7% 9% 8% 10% 12% 26%	2930
	21st to end	Night	7% 9% 5% 13% 9% 8% 7% 6% 9% 9% 18%	3087
August	1st to 10th	Night	5% 4 3 9% 6% 6% 6% 6% 8% 13% 34%	2825
	11th to 20th	Night	4 4 2 7% 5% 6% 7% 6% 10% 14% 36%	3081
	21st to end	Night	6% 5% 3 9% 7% 7% 7% 7% 10% 12% 27%	3828
September	1st to 10th	Night	6% 7% 3 9% 5% 6% 7% 7% 10% 13% 28%	2090
	11th to 20th	Night	9% 7% 3 10% 7% 6% 7% 5% 8% 10% 28%	2090
	21st to end	Night	10% 7% 3 9% 5% 6% 6% 5% 8% 9% 34%	2090
October	1st to 10th	Night	10% 5% 3 8% 5% 4 6% 5% 8% 9% 38%	2090
	11th to 20th	Night	6% 5% 2 5% 4 4 5% 4 6% 7% 52%	2256
	21st to end	Night	8% 5% 3 7% 4 3 4 4 5% 7% 51%	2508
November	1st to 10th	Night	7% 5% 2 4 4 5% 4 4 6% 8% 51%	2341
	11th to 20th	Night	9% 5% 2 6% 5% 4 5% 3 6% 7% 48%	2400
	21st to end	Night	7% 6% 3 6% 4 5% 4 4 5% 8% 48%	2520
December	1st to 10th	Night	4 3 1 4 3 3 3 3 5% 9% 61%	4250
	11th to 20th	Night	10% 7% 2 5% 4 4 4 3 5% 7% 50%	4822
	21st to end	Night	12% 8% 3 8% 5% 5% 5% 4 6% 8% 36%	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	31% 5% 7% 19% 27% 11%	4057
	11th to 20th	Day	51% 4 6% 17% 16% 6%	4060
	21st to end	Day	36% 4 6% 28% 21% 6%	4806
February	1st to 10th	Day	35% 5% 10% 19% 20% 11%	2000
	11th to 20th	Day	28% 5% 10% 21% 25% 11%	1958
	21st to end	Day	31% 5% 11% 17% 24% 11%	1730
March	1st to 10th	Day	34% 8% 11% 19% 21% 8%	4935
	11th to 20th	Day	22% 4 9% 23% 22% 19%	4980
	21st to end	Day	30% 5% 9% 28% 20% 9%	5465
April	1st to 10th	Day	29% 6% 15% 24% 19% 8%	2200
	11th to 20th	Day	33% 7% 11% 17% 21% 10%	2176
	21st to end	Day	26% 7% 10% 24% 26% 8%	2380
May	1st to 10th	Day	22% 9% 21% 29% 15% 4	5869
	11th to 20th	Day	29% 8% 16% 30% 15% 1	5865
	21st to end	Day	26% 10% 18% 30% 14% 1	6447
June	1st to 10th	Day	51% 10% 18% 17% 4	2600
	11th to 20th	Day	47% 12% 21% 18% 2	2600
	21st to end	Day	47% 13% 24% 13% 2 1	2600
July	1st to 10th	Day	47% 15% 29% 8% 1	4185
	11th to 20th	Day	46% 17% 30% 7%	4181
	21st to end	Day	47% 17% 25% 10% 1	4324
August	1st to 10th	Day	46% 13% 29% 10% 2	4091
	11th to 20th	Day	38% 14% 25% 18% 5%	3745
	21st to end	Day	47% 14% 26% 12% 1	3828
September	1st to 10th	Day	50% 16% 22% 11% 1	2090
	11th to 20th	Day	51% 14% 19% 12% 4	2090
	21st to end	Day	45% 11% 15% 17% 9% 2	2090
October	1st to 10th	Day	55% 11% 13% 10% 7% 5%	3480
	11th to 20th	Day	27% 6% 9% 22% 32% 4	3176
	21st to end	Day	29% 4 8% 23% 28% 7%	3428
November	1st to 10th	Day	30% 6% 11% 22% 20% 11%	1957
	11th to 20th	Day	36% 5% 9% 23% 19% 10%	2000
	21st to end	Day	35% 6% 9% 21% 20% 10%	1875
December	1st to 10th	Day	23% 4 14% 30% 19% 10%	2930
	11th to 20th	Day	34% 5% 11% 19% 21% 10%	3370
	21st to end	Day	43% 5% 11% 21% 15% 4	4466
January	1st to 10th	Night	31% 5% 8% 19% 26% 10%	5889
	11th to 20th	Night	54% 4 9% 16% 12% 4	5900
	21st to end	Night	40% 6% 9% 21% 17% 7%	6147
February	1st to 10th	Night	35% 6% 10% 20% 20% 9%	2400
	11th to 20th	Night	31% 6% 11% 20% 22% 9%	2339
	21st to end	Night	31% 6% 12% 21% 23% 8%	1899
March	1st to 10th	Night	35% 7% 11% 18% 20% 8%	4918
	11th to 20th	Night	20% 6% 16% 22% 18% 17%	4980
	21st to end	Night	32% 5% 9% 26% 21% 6%	5467
April	1st to 10th	Night	26% 5% 19% 27% 16% 7%	2200
	11th to 20th	Night	27% 7% 14% 23% 22% 7%	2173
	21st to end	Night	25% 5% 13% 27% 24% 6%	2019
May	1st to 10th	Night	24% 11% 19% 28% 13% 4	4116
	11th to 20th	Night	26% 9% 19% 30% 15% 1	4033
	21st to end	Night	23% 9% 22% 30% 15% 1	4429
June	1st to 10th	Night	39% 12% 24% 20% 5%	1800
	11th to 20th	Night	39% 12% 28% 18% 3	1800
	21st to end	Night	40% 15% 26% 14% 5%	1800
July	1st to 10th	Night	48% 15% 28% 7% 1	2885
	11th to 20th	Night	44% 20% 30% 6%	2876
	21st to end	Night	57% 15% 21% 7%	2988
August	1st to 10th	Night	38% 14% 33% 11% 4	2814
	11th to 20th	Night	34% 15% 32% 16% 3	3110
	21st to end	Night	43% 17% 29% 9% 1	3828
September	1st to 10th	Night	42% 20% 24% 13% 2	2090
	11th to 20th	Night	48% 13% 23% 15% 2	2090
	21st to end	Night	43% 10% 19% 18% 8% 2	2090
October	1st to 10th	Night	56% 11% 11% 11% 8% 4	3480
	11th to 20th	Night	27% 5% 8% 30% 24% 5%	3742
	21st to end	Night	29% 4 8% 26% 27% 6%	4120
November	1st to 10th	Night	29% 5% 13% 21% 20% 11%	2341
	11th to 20th	Night	34% 6% 9% 22% 20% 9%	2400
	21st to end	Night	33% 6% 9% 22% 21% 8%	2520
December	1st to 10th	Night	21% 5% 17% 30% 15% 12%	4250
	11th to 20th	Night	32% 7% 12% 21% 17% 10%	4824
	21st to end	Night	44% 7% 13% 19% 13% 4	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% 11% 42% 27% 10% 1	300
	11th to 20th	Day	9% 14% 34% 29% 11% 3	300
	21st to end	Day	14% 13% 43% 23% 6%	330
February	1st to 10th	Day	9% 10% 27% 32% 18% 4	300
	11th to 20th	Day	10% 10% 33% 30% 13% 4	300
	21st to end	Day	6% 10% 29% 32% 20% 2	329
March	1st to 10th	Day	4 8% 37% 37% 12% 2	500
	11th to 20th	Day	8% 8% 29% 32% 21% 3	500
	21st to end	Day	6% 7% 29% 34% 21% 3	550
April	1st to 10th	Day	6% 8% 31% 30% 21% 4	500
	11th to 20th	Day	6% 9% 26% 33% 22% 5%	492
	21st to end	Day	6% 5% 20% 31% 29% 9%	500
May	1st to 10th	Day	5% 3 15% 34% 30% 13%	503
	11th to 20th	Day	9% 3 15% 29% 28% 17%	527
	21st to end	Day	6% 3 7% 23% 33% 28%	573
June	1st to 10th	Day	14% 4 6% 22% 29% 25%	530
	11th to 20th	Day	8% 2 6% 19% 30% 34%	530
	21st to end	Day	4 2 4 12% 30% 48%	530
July	1st to 10th	Day	7% 2 3 9% 24% 56%	525
	11th to 20th	Day	5% 1 2 10% 31% 51%	524
	21st to end	Day	9% 1 3 14% 27% 45%	532
August	1st to 10th	Day	5% 2 4 14% 28% 47%	486
	11th to 20th	Day	4 3 3 12% 27% 51%	479
	21st to end	Day	10% 3 4 16% 31% 37%	539
September	1st to 10th	Day	8% 2 6% 12% 31% 42%	490
	11th to 20th	Day	9% 3 4 20% 31% 32%	490
	21st to end	Day	7% 2 6% 21% 34% 29%	490
October	1st to 10th	Day	10% 4 14% 32% 30% 10%	490
	11th to 20th	Day	5% 3 17% 33% 33% 9%	490
	21st to end	Day	7% 2 17% 40% 29% 5%	539
November	1st to 10th	Day	9% 5% 19% 34% 28% 5%	495
	11th to 20th	Day	12% 6% 19% 37% 22% 5%	500
	21st to end	Day	9% 5% 32% 31% 19% 5%	375
December	1st to 10th	Day	4 10% 31% 33% 15% 7%	300
	11th to 20th	Day	9% 10% 31% 32% 15% 3	300
	21st to end	Day	7% 8% 30% 34% 17% 4	330
January	1st to 10th	Night	10% 7% 31% 37% 14% 1	800
	11th to 20th	Night	13% 7% 25% 42% 12% 1	800
	21st to end	Night	14% 7% 35% 34% 10%	880
February	1st to 10th	Night	14% 6% 27% 38% 14% 1	800
	11th to 20th	Night	10% 6% 29% 42% 12% 1	783
	21st to end	Night	10% 5% 29% 44% 12%	660
March	1st to 10th	Night	7% 5% 35% 43% 10% 1	800
	11th to 20th	Night	7% 6% 29% 42% 16% 1	800
	21st to end	Night	7% 4 30% 43% 16% 1	880
April	1st to 10th	Night	6% 5% 28% 45% 16%	800
	11th to 20th	Night	7% 4 29% 43% 17% 1	791
	21st to end	Night	6% 4 24% 47% 19%	800
May	1st to 10th	Night	4 2 15% 48% 28% 3	630
	11th to 20th	Night	7% 3 14% 43% 30% 3	591
	21st to end	Night	6% 2 8% 37% 41% 6%	650
June	1st to 10th	Night	10% 2 5% 29% 45% 9%	600
	11th to 20th	Night	6% 3 4 18% 47% 22%	600
	21st to end	Night	5% 1 4 16% 44% 31%	600
July	1st to 10th	Night	7% 2 2 10% 49% 30%	585
	11th to 20th	Night	5% 2 1 10% 47% 36%	582
	21st to end	Night	5% 2 2 9% 48% 34%	624
August	1st to 10th	Night	4 1 1 11% 49% 33%	567
	11th to 20th	Night	5% 2 2 7% 44% 40%	571
	21st to end	Night	11% 3 4 19% 40% 22%	836
September	1st to 10th	Night	8% 3 5% 20% 43% 20%	760
	11th to 20th	Night	12% 4 4 27% 39% 15%	760
	21st to end	Night	13% 3 6% 29% 38% 12%	760
October	1st to 10th	Night	12% 3 14% 37% 29% 4	760
	11th to 20th	Night	7% 1 16% 40% 32% 3	760
	21st to end	Night	10% 3 18% 42% 26% 2	836
November	1st to 10th	Night	8% 3 24% 39% 22% 3	780
	11th to 20th	Night	10% 4 19% 45% 21% 2	800
	21st to end	Night	9% 4 25% 45% 17% 1	800
December	1st to 10th	Night	8% 5% 23% 42% 22% 1	800
	11th to 20th	Night	10% 6% 24% 40% 19% 1	800
	21st to end	Night	9% 6% 26% 41% 17% 1	880

Page generated at 2025-07-18 01:09:58. Version ac07

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