CFAS Ocala Forest Site
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the CFAS Ocala Forest Site clear sky chart from 2005-11-06 to 2025-04-26.

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% 6% 2 7% 5% 5% 6% 5% 7% 10% 39%	114014
	Night	9% 6% 2 6% 4 4 5% 4 6% 9% 44%	114607
Transparency	Day	39% 6% 15% 20% 15% 6%	117769
	Night	37% 6% 15% 20% 15% 6%	118991
Seeing	Day	10% 7% 21% 25% 21% 14%	16126
	Night	11% 6% 21% 31% 24% 7%	26273

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% 5% 1 6% 3 3 3 2 4 7% 55%	4056
	11th to 20th	Day	20% 10% 4 7% 5% 4 4 3 4 5% 34%	4060
	21st to end	Day	13% 6% 2 5% 3 4 4 3 5% 8% 48%	4558
February	1st to 10th	Day	12% 7% 2 7% 4 3 5% 4 6% 7% 42%	2000
	11th to 20th	Day	10% 5% 2 5% 4 4 4 3 4 7% 52%	1948
	21st to end	Day	9% 6% 3 6% 4 4 4 4 6% 7% 47%	1747
March	1st to 10th	Day	8% 6% 2 8% 5% 4 5% 4 6% 9% 42%	4935
	11th to 20th	Day	6% 4 1 5% 3 3 3 3 5% 8% 59%	4980
	21st to end	Day	9% 5% 2 6% 4 4 5% 4 6% 9% 46%	5465
April	1st to 10th	Day	7% 4 2 5% 4 5% 5% 4 5% 10% 49%	2200
	11th to 20th	Day	7% 5% 3 6% 6% 5% 6% 5% 6% 7% 44%	2225
	21st to end	Day	5% 4 1 5% 4 4 4 4 7% 9% 51%	2340
May	1st to 10th	Day	3 3 1 4 4 4 5% 4 7% 11% 55%	4066
	11th to 20th	Day	10% 5% 2 7% 6% 5% 7% 5% 7% 9% 36%	4081
	21st to end	Day	4 4 2 4 4 4 5% 5% 6% 10% 51%	4476
June	1st to 10th	Day	9% 7% 3 9% 8% 7% 7% 5% 8% 11% 25%	2470
	11th to 20th	Day	6% 5% 2 9% 8% 9% 9% 7% 8% 10% 27%	2470
	21st to end	Day	9% 6% 3 9% 8% 7% 7% 7% 9% 10% 26%	2470
July	1st to 10th	Day	6% 7% 3 9% 7% 9% 8% 7% 11% 13% 21%	4120
	11th to 20th	Day	4 5% 3 9% 8% 8% 8% 6% 10% 15% 24%	4120
	21st to end	Day	5% 6% 3 9% 7% 8% 8% 7% 11% 14% 23%	4466
August	1st to 10th	Day	7% 7% 3 10% 6% 6% 7% 6% 10% 12% 26%	4104
	11th to 20th	Day	5% 4 2 7% 5% 6% 7% 6% 9% 13% 34%	3921
	21st to end	Day	7% 6% 3 10% 7% 7% 8% 6% 9% 12% 24%	3828
September	1st to 10th	Day	7% 7% 3 10% 9% 8% 8% 7% 9% 10% 21%	2090
	11th to 20th	Day	10% 8% 3 11% 7% 7% 7% 6% 8% 9% 23%	2090
	21st to end	Day	10% 7% 3 9% 7% 6% 6% 5% 6% 9% 32%	2090
October	1st to 10th	Day	12% 6% 3 8% 5% 6% 6% 5% 7% 7% 33%	2062
	11th to 20th	Day	7% 4 2 5% 5% 4 5% 4 7% 9% 48%	1900
	21st to end	Day	9% 4 1 5% 4 5% 5% 4 5% 9% 48%	2090
November	1st to 10th	Day	9% 5% 3 5% 4 5% 5% 4 6% 8% 46%	1957
	11th to 20th	Day	10% 6% 3 6% 5% 6% 5% 4 5% 7% 42%	2000
	21st to end	Day	10% 6% 3 7% 5% 4 4 4 5% 7% 46%	1860
December	1st to 10th	Day	5% 4 1 5% 3 3 4 4 7% 8% 55%	2930
	11th to 20th	Day	11% 7% 3 6% 6% 6% 6% 4 6% 8% 37%	3373
	21st to end	Day	12% 7% 3 8% 4 4 5% 3 5% 7% 43%	4466
January	1st to 10th	Night	9% 5% 2 4 3 3 3 3 4 8% 56%	5889
	11th to 20th	Night	20% 10% 3 7% 4 4 3 4 5% 7% 32%	5900
	21st to end	Night	15% 6% 2 5% 4 4 4 3 6% 8% 42%	6380
February	1st to 10th	Night	13% 7% 2 6% 4 3 4 3 6% 7% 45%	2400
	11th to 20th	Night	10% 5% 2 6% 4 4 4 4 5% 7% 48%	2338
	21st to end	Night	8% 5% 2 5% 4 5% 4 3 6% 7% 51%	1880
March	1st to 10th	Night	14% 8% 3 7% 3 3 4 3 5% 6% 44%	4918
	11th to 20th	Night	6% 5% 1 4 3 4 4 3 6% 9% 55%	4980
	21st to end	Night	9% 5% 2 6% 4 4 4 3 5% 8% 50%	5467
April	1st to 10th	Night	9% 4 1 4 4 3 5% 4 6% 9% 51%	2200
	11th to 20th	Night	8% 5% 2 6% 4 4 3 3 6% 8% 53%	2124
	21st to end	Night	6% 4 1 4 4 4 4 4 6% 8% 54%	1957
May	1st to 10th	Night	5% 3 1 4 4 3 4 4 6% 9% 59%	2856
	11th to 20th	Night	7% 5% 2 6% 4 5% 5% 4 7% 11% 44%	2812
	21st to end	Night	4 3 1 4 3 3 4 3 6% 8% 62%	3079
June	1st to 10th	Night	10% 5% 3 7% 5% 5% 6% 5% 8% 11% 36%	1710
	11th to 20th	Night	5% 5% 2 7% 7% 6% 7% 7% 8% 11% 33%	1710
	21st to end	Night	7% 7% 3 7% 7% 7% 6% 6% 9% 11% 32%	1710
July	1st to 10th	Night	6% 7% 3 9% 6% 7% 7% 7% 8% 12% 27%	2840
	11th to 20th	Night	4 5% 2 8% 8% 8% 9% 6% 10% 13% 28%	2840
	21st to end	Night	6% 8% 4 11% 7% 7% 7% 6% 10% 13% 23%	3087
August	1st to 10th	Night	6% 5% 2 8% 6% 6% 7% 5% 8% 13% 34%	2825
	11th to 20th	Night	4 4 2 6% 5% 6% 6% 5% 9% 14% 39%	2866
	21st to end	Night	7% 7% 3 8% 5% 5% 6% 5% 9% 12% 33%	3828
September	1st to 10th	Night	9% 6% 3 9% 6% 6% 5% 6% 8% 11% 31%	2090
	11th to 20th	Night	10% 8% 4 9% 6% 6% 6% 6% 7% 11% 28%	2090
	21st to end	Night	10% 7% 2 7% 4 6% 6% 5% 7% 9% 37%	2090
October	1st to 10th	Night	11% 7% 3 7% 5% 5% 5% 4 6% 8% 39%	2115
	11th to 20th	Night	5% 4 2 5% 4 5% 4 4 6% 10% 52%	2280
	21st to end	Night	9% 5% 2 5% 3 4 4 3 5% 7% 51%	2508
November	1st to 10th	Night	10% 5% 2 5% 4 3 4 4 6% 8% 48%	2341
	11th to 20th	Night	10% 7% 2 7% 4 4 4 4 6% 7% 44%	2400
	21st to end	Night	9% 7% 2 6% 4 5% 4 4 6% 8% 46%	2535
December	1st to 10th	Night	6% 4 2 6% 4 3 3 3 4 7% 58%	4250
	11th to 20th	Night	10% 7% 2 7% 4 4 4 3 5% 6% 47%	4822
	21st to end	Night	14% 9% 3 7% 5% 4 4 4 5% 7% 39%	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% 2 8% 15% 28% 15%	4057
	11th to 20th	Day	54% 2 4 14% 17% 8%	4060
	21st to end	Day	36% 2 8% 27% 17% 9%	4558
February	1st to 10th	Day	40% 5% 9% 15% 21% 10%	2000
	11th to 20th	Day	34% 3 9% 20% 23% 12%	1958
	21st to end	Day	36% 3 10% 18% 22% 10%	1747
March	1st to 10th	Day	39% 3 13% 18% 20% 8%	4935
	11th to 20th	Day	25% 2 10% 22% 24% 17%	4980
	21st to end	Day	34% 3 10% 27% 17% 9%	5465
April	1st to 10th	Day	31% 4 13% 22% 21% 9%	2200
	11th to 20th	Day	38% 5% 9% 18% 22% 8%	2225
	21st to end	Day	29% 4 12% 24% 23% 8%	2340
May	1st to 10th	Day	22% 4 17% 33% 18% 5%	4104
	11th to 20th	Day	43% 4 17% 24% 10% 2	4085
	21st to end	Day	28% 4 14% 35% 17% 1	4489
June	1st to 10th	Day	52% 8% 17% 17% 6% 1	2470
	11th to 20th	Day	48% 9% 19% 21% 3	2470
	21st to end	Day	49% 9% 22% 16% 4	2470
July	1st to 10th	Day	47% 13% 28% 12% 1	4055
	11th to 20th	Day	45% 14% 33% 8%	4051
	21st to end	Day	44% 15% 31% 10% 1	4324
August	1st to 10th	Day	46% 11% 28% 12% 2	4091
	11th to 20th	Day	36% 12% 25% 23% 5%	3960
	21st to end	Day	48% 11% 23% 16% 2	3828
September	1st to 10th	Day	53% 13% 18% 11% 4 1	2090
	11th to 20th	Day	54% 7% 19% 14% 5%	2090
	21st to end	Day	48% 7% 12% 18% 12% 3	2090
October	1st to 10th	Day	57% 6% 12% 12% 7% 6%	3426
	11th to 20th	Day	27% 4 8% 22% 30% 9%	3140
	21st to end	Day	27% 4 7% 23% 32% 7%	3428
November	1st to 10th	Day	36% 4 9% 21% 19% 11%	1957
	11th to 20th	Day	41% 4 9% 17% 21% 9%	2000
	21st to end	Day	38% 4 8% 21% 22% 7%	1860
December	1st to 10th	Day	25% 4 16% 26% 20% 9%	2930
	11th to 20th	Day	42% 5% 10% 17% 17% 9%	3370
	21st to end	Day	41% 4 9% 22% 19% 5%	4466
January	1st to 10th	Night	30% 2 7% 17% 31% 13%	5889
	11th to 20th	Night	52% 3 8% 17% 17% 4	5900
	21st to end	Night	41% 2 10% 22% 16% 9%	6380
February	1st to 10th	Night	38% 4 10% 18% 19% 12%	2400
	11th to 20th	Night	36% 4 11% 19% 20% 11%	2339
	21st to end	Night	33% 4 12% 19% 22% 10%	1880
March	1st to 10th	Night	42% 3 11% 16% 19% 9%	4918
	11th to 20th	Night	28% 2 13% 22% 18% 17%	4980
	21st to end	Night	34% 3 11% 25% 20% 8%	5467
April	1st to 10th	Night	29% 5% 17% 25% 16% 9%	2200
	11th to 20th	Night	30% 4 10% 27% 20% 8%	2124
	21st to end	Night	27% 4 13% 27% 21% 7%	1957
May	1st to 10th	Night	24% 4 20% 32% 16% 4	2883
	11th to 20th	Night	35% 5% 23% 26% 10% 2	2813
	21st to end	Night	20% 5% 15% 39% 20% 1	3087
June	1st to 10th	Night	41% 7% 23% 23% 5%	1710
	11th to 20th	Night	41% 9% 26% 22% 3	1710
	21st to end	Night	44% 10% 25% 16% 5% 1	1710
July	1st to 10th	Night	44% 13% 30% 12% 1	2795
	11th to 20th	Night	43% 16% 32% 7% 1	2786
	21st to end	Night	47% 14% 29% 10% 1	2988
August	1st to 10th	Night	40% 11% 35% 12% 2	2814
	11th to 20th	Night	32% 11% 30% 22% 5%	2893
	21st to end	Night	41% 13% 28% 16% 2	3828
September	1st to 10th	Night	45% 13% 22% 15% 5%	2090
	11th to 20th	Night	48% 9% 22% 15% 4	2090
	21st to end	Night	42% 7% 17% 22% 10% 2	2090
October	1st to 10th	Night	55% 7% 12% 14% 8% 5%	3531
	11th to 20th	Night	26% 4 8% 22% 34% 6%	3779
	21st to end	Night	29% 4 9% 21% 30% 6%	4120
November	1st to 10th	Night	33% 5% 11% 22% 19% 10%	2341
	11th to 20th	Night	39% 4 9% 20% 19% 10%	2400
	21st to end	Night	36% 4 10% 22% 20% 8%	2535
December	1st to 10th	Night	28% 3 13% 28% 14% 13%	4250
	11th to 20th	Night	38% 4 11% 22% 16% 9%	4824
	21st to end	Night	44% 4 11% 21% 14% 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	12% 14% 48% 20% 4 2	300
	11th to 20th	Day	11% 18% 39% 22% 7% 3	300
	21st to end	Day	16% 23% 43% 14% 4	330
February	1st to 10th	Day	18% 13% 33% 24% 10% 1	300
	11th to 20th	Day	14% 12% 44% 20% 8% 2	300
	21st to end	Day	10% 16% 29% 29% 15% 1	346
March	1st to 10th	Day	9% 18% 32% 28% 11% 1	500
	11th to 20th	Day	12% 14% 29% 27% 14% 4	500
	21st to end	Day	11% 13% 29% 28% 16% 2	550
April	1st to 10th	Day	10% 13% 30% 31% 13% 3	500
	11th to 20th	Day	10% 11% 29% 30% 15% 5%	492
	21st to end	Day	7% 7% 26% 31% 18% 11%	480
May	1st to 10th	Day	6% 7% 21% 32% 24% 11%	463
	11th to 20th	Day	8% 4 21% 27% 26% 13%	487
	21st to end	Day	7% 4 12% 25% 35% 17%	529
June	1st to 10th	Day	12% 2 13% 25% 29% 18%	490
	11th to 20th	Day	7% 3 14% 22% 28% 26%	490
	21st to end	Day	7% 2 7% 21% 33% 31%	490
July	1st to 10th	Day	9% 1 4 15% 29% 41%	485
	11th to 20th	Day	5% 1 4 17% 30% 43%	484
	21st to end	Day	8% 2 7% 16% 30% 37%	532
August	1st to 10th	Day	7% 3 11% 18% 30% 31%	486
	11th to 20th	Day	6% 1 5% 15% 32% 41%	479
	21st to end	Day	10% 1 8% 20% 31% 30%	539
September	1st to 10th	Day	9% 2 9% 17% 33% 29%	490
	11th to 20th	Day	11% 4 9% 28% 27% 22%	490
	21st to end	Day	11% 4 10% 24% 30% 22%	490
October	1st to 10th	Day	14% 6% 23% 30% 20% 6%	490
	11th to 20th	Day	7% 7% 20% 35% 24% 7%	490
	21st to end	Day	10% 4 26% 35% 20% 5%	539
November	1st to 10th	Day	12% 8% 24% 32% 20% 4	495
	11th to 20th	Day	14% 7% 29% 30% 17% 3	500
	21st to end	Day	12% 11% 35% 28% 12% 3	360
December	1st to 10th	Day	8% 15% 37% 25% 13% 3	300
	11th to 20th	Day	17% 13% 35% 25% 9% 1	300
	21st to end	Day	11% 10% 35% 32% 11% 1	330
January	1st to 10th	Night	14% 12% 34% 28% 12%	800
	11th to 20th	Night	13% 11% 27% 35% 14% 1	800
	21st to end	Night	18% 13% 34% 28% 7%	880
February	1st to 10th	Night	17% 7% 31% 32% 13% 1	800
	11th to 20th	Night	13% 9% 31% 36% 10% 1	783
	21st to end	Night	13% 8% 35% 37% 7%	660
March	1st to 10th	Night	8% 11% 35% 34% 11%	800
	11th to 20th	Night	11% 11% 33% 31% 14% 1	800
	21st to end	Night	9% 9% 31% 38% 13%	880
April	1st to 10th	Night	10% 8% 33% 37% 12%	800
	11th to 20th	Night	10% 10% 30% 34% 16% 1	791
	21st to end	Night	6% 6% 27% 42% 17% 1	783
May	1st to 10th	Night	6% 3 23% 45% 23% 2	600
	11th to 20th	Night	7% 2 15% 43% 29% 3	561
	21st to end	Night	7% 1 11% 37% 39% 6%	617
June	1st to 10th	Night	11% 3 9% 33% 38% 6%	570
	11th to 20th	Night	7% 3 6% 26% 37% 21%	570
	21st to end	Night	9% 2 5% 23% 42% 19%	570
July	1st to 10th	Night	9% 1 6% 16% 41% 26%	555
	11th to 20th	Night	7% 1 2 13% 48% 29%	552
	21st to end	Night	6% 1 5% 16% 49% 23%	624
August	1st to 10th	Night	8% 1 5% 17% 47% 22%	567
	11th to 20th	Night	6% 1 5% 14% 47% 27%	578
	21st to end	Night	13% 3 8% 21% 36% 20%	836
September	1st to 10th	Night	11% 2 7% 22% 40% 18%	760
	11th to 20th	Night	14% 3 9% 28% 35% 12%	760
	21st to end	Night	14% 2 9% 27% 37% 11%	760
October	1st to 10th	Night	15% 4 16% 36% 25% 4	760
	11th to 20th	Night	5% 4 18% 38% 31% 4	760
	21st to end	Night	11% 5% 19% 38% 25% 3	836
November	1st to 10th	Night	13% 4 23% 34% 23% 2	780
	11th to 20th	Night	14% 6% 25% 35% 19% 3	800
	21st to end	Night	11% 6% 30% 36% 17% 1	800
December	1st to 10th	Night	10% 7% 26% 35% 21% 1	800
	11th to 20th	Night	13% 8% 26% 34% 17% 1	800
	21st to end	Night	14% 8% 28% 35% 15%	880

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