Jacksonville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Jacksonville clear sky chart from 2005-11-06 to 2024-04-03.

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	10% 6% 3 6% 6% 4 6% 6% 6% 9% 39%	79226
	Night	10% 6% 3 5% 5% 3 5% 5% 6% 9% 43%	80905
Transparency	Day	40% 9% 14% 17% 14% 6%	78949
	Night	37% 9% 15% 18% 15% 7%	80701
Seeing	Day	10% 7% 21% 26% 22% 13%	14589
	Night	11% 6% 21% 32% 25% 5%	24754

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	12% 8% 2 5% 4 4 4 4 4 6% 48%	2836
	11th to 20th	Day	16% 8% 3 7% 6% 4 3 4 4 6% 40%	2840
	21st to end	Day	12% 6% 3 6% 4 3 4 4 6% 7% 45%	3124
February	1st to 10th	Day	15% 7% 3 5% 5% 3 4 4 4 6% 43%	1895
	11th to 20th	Day	12% 6% 2 5% 4 3 4 4 5% 6% 50%	1848
	21st to end	Day	12% 6% 3 5% 4 3 4 4 5% 6% 48%	1642
March	1st to 10th	Day	9% 5% 3 4 5% 2 3 4 5% 8% 52%	2090
	11th to 20th	Day	9% 4 2 4 5% 2 4 5% 6% 8% 50%	2090
	21st to end	Day	10% 6% 3 5% 5% 3 4 4 4 8% 48%	2299
April	1st to 10th	Day	8% 5% 3 5% 6% 3 5% 4 6% 7% 48%	2002
	11th to 20th	Day	9% 6% 3 7% 5% 4 5% 6% 5% 8% 42%	2016
	21st to end	Day	6% 4 2 5% 4 4 5% 5% 6% 9% 52%	2195
May	1st to 10th	Day	7% 3 2 4 4 2 4 4 6% 9% 54%	2340
	11th to 20th	Day	8% 3 2 6% 6% 3 6% 7% 8% 11% 39%	2301
	21st to end	Day	9% 4 2 6% 7% 5% 7% 7% 8% 10% 36%	2531
June	1st to 10th	Day	12% 6% 3 6% 8% 5% 6% 8% 8% 9% 29%	2340
	11th to 20th	Day	6% 4 3 7% 7% 5% 8% 9% 9% 11% 31%	2340
	21st to end	Day	7% 5% 4 8% 8% 5% 9% 7% 8% 11% 28%	2340
July	1st to 10th	Day	8% 6% 3 7% 7% 4 9% 8% 9% 11% 28%	2340
	11th to 20th	Day	7% 5% 4 9% 8% 6% 9% 8% 8% 11% 24%	2340
	21st to end	Day	6% 5% 3 7% 8% 5% 8% 9% 8% 12% 28%	2547
August	1st to 10th	Day	8% 6% 2 7% 9% 5% 8% 9% 9% 11% 26%	2327
	11th to 20th	Day	9% 5% 3 8% 9% 5% 8% 10% 8% 11% 23%	2295
	21st to end	Day	11% 6% 3 8% 9% 6% 9% 8% 8% 9% 23%	2190
September	1st to 10th	Day	10% 7% 3 8% 8% 5% 8% 8% 8% 11% 24%	1980
	11th to 20th	Day	13% 7% 3 7% 9% 5% 8% 8% 8% 9% 24%	1980
	21st to end	Day	12% 7% 3 8% 7% 4 6% 6% 6% 7% 33%	1980
October	1st to 10th	Day	12% 6% 3 6% 7% 4 6% 5% 7% 8% 36%	1944
	11th to 20th	Day	7% 5% 3 5% 5% 4 6% 4 5% 8% 49%	1800
	21st to end	Day	9% 6% 2 5% 5% 3 4 5% 5% 8% 48%	1980
November	1st to 10th	Day	12% 5% 3 5% 6% 3 5% 5% 5% 8% 45%	1857
	11th to 20th	Day	12% 5% 2 6% 6% 4 5% 4 5% 8% 42%	1900
	21st to end	Day	12% 6% 4 6% 5% 3 5% 4 6% 6% 44%	1710
December	1st to 10th	Day	9% 5% 2 6% 5% 2 5% 5% 6% 10% 44%	1710
	11th to 20th	Day	14% 7% 2 6% 5% 3 4 5% 5% 6% 43%	2153
	21st to end	Day	15% 9% 3 6% 5% 3 5% 4 4 6% 42%	3124
January	1st to 10th	Night	13% 8% 4 5% 5% 2 4 4 6% 7% 42%	4109
	11th to 20th	Night	11% 9% 3 7% 6% 3 5% 5% 6% 8% 37%	4120
	21st to end	Night	13% 8% 3 6% 6% 3 4 4 5% 7% 41%	4532
February	1st to 10th	Night	14% 7% 2 5% 5% 3 4 4 5% 6% 45%	2280
	11th to 20th	Night	13% 6% 3 5% 5% 3 4 4 4 6% 48%	2218
	21st to end	Night	11% 7% 2 5% 5% 2 5% 4 5% 6% 48%	1809
March	1st to 10th	Night	9% 5% 3 4 5% 2 4 4 4 6% 54%	2090
	11th to 20th	Night	8% 5% 2 5% 4 3 4 5% 6% 8% 49%	2090
	21st to end	Night	9% 5% 2 5% 4 2 4 5% 4 6% 54%	2299
April	1st to 10th	Night	8% 5% 2 4 5% 3 5% 5% 6% 8% 50%	2003
	11th to 20th	Night	9% 5% 2 5% 5% 3 4 5% 4 8% 51%	1890
	21st to end	Night	6% 3 1 3 4 3 4 6% 7% 9% 54%	1778
May	1st to 10th	Night	5% 3 1 3 4 2 4 4 5% 8% 61%	1620
	11th to 20th	Night	5% 4 2 4 5% 3 4 6% 8% 11% 49%	1592
	21st to end	Night	6% 4 2 5% 6% 4 6% 6% 7% 10% 45%	1744
June	1st to 10th	Night	11% 5% 2 5% 5% 3 5% 7% 7% 12% 37%	1620
	11th to 20th	Night	5% 4 2 5% 6% 5% 8% 7% 9% 13% 36%	1620
	21st to end	Night	7% 4 3 5% 7% 4 6% 6% 9% 13% 36%	1620
July	1st to 10th	Night	6% 5% 2 6% 7% 4 6% 8% 9% 12% 35%	1620
	11th to 20th	Night	6% 5% 2 7% 7% 5% 7% 7% 9% 12% 34%	1620
	21st to end	Night	5% 4 2 6% 6% 3 6% 8% 9% 12% 38%	1771
August	1st to 10th	Night	4 4 3 7% 7% 5% 7% 7% 10% 14% 32%	1611
	11th to 20th	Night	5% 5% 3 5% 6% 5% 7% 8% 8% 12% 37%	1598
	21st to end	Night	9% 7% 3 6% 8% 5% 7% 6% 8% 12% 28%	2150
September	1st to 10th	Night	10% 6% 3 7% 7% 5% 7% 7% 7% 12% 28%	1980
	11th to 20th	Night	11% 7% 3 8% 7% 5% 7% 8% 7% 10% 27%	1980
	21st to end	Night	9% 5% 3 6% 6% 4 6% 6% 7% 8% 39%	1980
October	1st to 10th	Night	10% 6% 3 7% 5% 3 5% 6% 6% 7% 42%	2015
	11th to 20th	Night	8% 4 2 5% 4 3 4 4 4 7% 54%	2160
	21st to end	Night	9% 5% 2 5% 5% 2 4 5% 5% 8% 50%	2376
November	1st to 10th	Night	11% 5% 2 5% 5% 3 4 4 5% 8% 48%	2221
	11th to 20th	Night	11% 5% 3 6% 4 3 5% 5% 5% 7% 47%	2280
	21st to end	Night	12% 6% 2 5% 4 3 5% 4 5% 8% 45%	2465
December	1st to 10th	Night	12% 6% 2 5% 5% 3 4 5% 6% 8% 45%	2470
	11th to 20th	Night	14% 7% 3 5% 4 3 3 3 5% 6% 46%	3042
	21st to end	Night	14% 8% 3 7% 5% 3 5% 4 5% 7% 39%	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	38% 4 7% 18% 22% 11%	2837
	11th to 20th	Day	46% 5% 6% 14% 19% 11%	2840
	21st to end	Day	38% 6% 9% 18% 17% 12%	3124
February	1st to 10th	Day	42% 6% 9% 14% 20% 10%	1895
	11th to 20th	Day	35% 5% 9% 16% 23% 12%	1858
	21st to end	Day	36% 6% 11% 16% 19% 12%	1642
March	1st to 10th	Day	31% 5% 11% 22% 22% 10%	2090
	11th to 20th	Day	32% 6% 15% 21% 18% 9%	2090
	21st to end	Day	35% 5% 12% 19% 20% 9%	2299
April	1st to 10th	Day	33% 7% 12% 18% 19% 11%	2002
	11th to 20th	Day	39% 7% 10% 18% 19% 7%	2016
	21st to end	Day	27% 6% 13% 23% 23% 8%	2195
May	1st to 10th	Day	27% 6% 10% 24% 24% 9%	2340
	11th to 20th	Day	35% 10% 18% 20% 14% 4	2305
	21st to end	Day	39% 10% 14% 19% 16% 2	2531
June	1st to 10th	Day	47% 12% 17% 16% 8% 1	2340
	11th to 20th	Day	39% 15% 21% 20% 5%	2340
	21st to end	Day	45% 15% 22% 12% 6%	2340
July	1st to 10th	Day	44% 16% 23% 16% 2	2275
	11th to 20th	Day	48% 14% 24% 10% 4	2271
	21st to end	Day	41% 16% 25% 17% 2	2405
August	1st to 10th	Day	45% 15% 25% 14% 2	2314
	11th to 20th	Day	48% 16% 24% 11% 1	2295
	21st to end	Day	51% 15% 18% 13% 2	2190
September	1st to 10th	Day	50% 14% 17% 10% 7% 1	1980
	11th to 20th	Day	52% 14% 15% 13% 6%	1980
	21st to end	Day	47% 8% 15% 15% 12% 3	1980
October	1st to 10th	Day	44% 8% 10% 16% 13% 9%	1944
	11th to 20th	Day	33% 6% 9% 21% 26% 6%	1800
	21st to end	Day	33% 5% 9% 18% 21% 13%	1980
November	1st to 10th	Day	36% 6% 11% 18% 18% 11%	1857
	11th to 20th	Day	40% 6% 9% 15% 20% 10%	1900
	21st to end	Day	40% 5% 10% 18% 21% 6%	1710
December	1st to 10th	Day	35% 6% 17% 21% 15% 6%	1710
	11th to 20th	Day	40% 7% 10% 16% 19% 8%	2150
	21st to end	Day	45% 4 7% 17% 18% 8%	3124
January	1st to 10th	Night	41% 5% 7% 14% 20% 13%	4109
	11th to 20th	Night	44% 5% 8% 16% 18% 9%	4120
	21st to end	Night	41% 8% 10% 14% 15% 12%	4532
February	1st to 10th	Night	40% 6% 9% 16% 18% 11%	2280
	11th to 20th	Night	38% 6% 8% 18% 18% 13%	2219
	21st to end	Night	37% 5% 10% 19% 17% 12%	1809
March	1st to 10th	Night	31% 5% 12% 23% 19% 10%	2090
	11th to 20th	Night	32% 7% 16% 21% 15% 10%	2090
	21st to end	Night	31% 5% 13% 22% 18% 10%	2299
April	1st to 10th	Night	32% 7% 14% 20% 17% 11%	2003
	11th to 20th	Night	32% 6% 10% 23% 20% 8%	1890
	21st to end	Night	24% 8% 14% 28% 20% 6%	1778
May	1st to 10th	Night	23% 7% 13% 27% 24% 7%	1620
	11th to 20th	Night	27% 10% 22% 24% 15% 3	1593
	21st to end	Night	31% 10% 17% 24% 17% 2	1745
June	1st to 10th	Night	37% 12% 22% 20% 8%	1620
	11th to 20th	Night	35% 13% 24% 23% 5%	1620
	21st to end	Night	35% 15% 26% 17% 6% 1	1620
July	1st to 10th	Night	38% 16% 25% 19% 2 1	1575
	11th to 20th	Night	39% 17% 25% 15% 4	1566
	21st to end	Night	32% 16% 28% 22% 2	1672
August	1st to 10th	Night	35% 17% 31% 14% 3	1600
	11th to 20th	Night	34% 18% 30% 16% 1	1598
	21st to end	Night	46% 14% 23% 14% 3	2150
September	1st to 10th	Night	44% 15% 20% 13% 5% 1	1980
	11th to 20th	Night	47% 15% 18% 14% 7%	1980
	21st to end	Night	39% 11% 15% 19% 14% 3	1980
October	1st to 10th	Night	38% 9% 12% 18% 14% 9%	2015
	11th to 20th	Night	29% 6% 10% 23% 26% 6%	2160
	21st to end	Night	32% 7% 11% 17% 22% 12%	2376
November	1st to 10th	Night	34% 7% 10% 19% 18% 12%	2221
	11th to 20th	Night	37% 6% 9% 17% 20% 10%	2280
	21st to end	Night	38% 5% 12% 20% 18% 7%	2465
December	1st to 10th	Night	35% 6% 17% 22% 14% 6%	2470
	11th to 20th	Night	39% 5% 10% 16% 20% 9%	3044
	21st to end	Night	45% 6% 11% 16% 18% 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	13% 12% 47% 23% 4 1	270
	11th to 20th	Day	6% 13% 41% 27% 11% 2	270
	21st to end	Day	16% 19% 44% 18% 3	297
February	1st to 10th	Day	13% 16% 36% 25% 8% 1	270
	11th to 20th	Day	15% 13% 40% 23% 9%	270
	21st to end	Day	10% 14% 36% 31% 9%	297
March	1st to 10th	Day	11% 14% 33% 29% 12% 1	460
	11th to 20th	Day	13% 10% 32% 27% 14% 3	460
	21st to end	Day	11% 13% 32% 25% 16% 1	506
April	1st to 10th	Day	11% 13% 29% 28% 16% 3	428
	11th to 20th	Day	9% 13% 30% 26% 14% 7%	412
	21st to end	Day	6% 7% 29% 29% 19% 11%	420
May	1st to 10th	Day	4 8% 26% 32% 20% 9%	423
	11th to 20th	Day	8% 2 19% 32% 27% 13%	447
	21st to end	Day	8% 4 11% 25% 33% 19%	485
June	1st to 10th	Day	14% 3 10% 28% 25% 19%	450
	11th to 20th	Day	6% 2 12% 24% 30% 27%	450
	21st to end	Day	5% 3 8% 22% 34% 28%	450
July	1st to 10th	Day	5% 2 6% 17% 33% 37%	445
	11th to 20th	Day	4 1 4 17% 35% 38%	444
	21st to end	Day	6% 2 5% 22% 36% 28%	488
August	1st to 10th	Day	9% 8% 20% 32% 29%	446
	11th to 20th	Day	6% 2 4 18% 33% 38%	439
	21st to end	Day	10% 2 7% 24% 30% 28%	495
September	1st to 10th	Day	11% 3 8% 19% 30% 30%	450
	11th to 20th	Day	13% 3 12% 27% 28% 18%	450
	21st to end	Day	13% 3 9% 24% 33% 17%	450
October	1st to 10th	Day	14% 5% 23% 30% 21% 6%	450
	11th to 20th	Day	7% 6% 20% 32% 30% 6%	450
	21st to end	Day	11% 5% 23% 33% 22% 5%	495
November	1st to 10th	Day	16% 6% 25% 29% 19% 5%	455
	11th to 20th	Day	15% 10% 28% 30% 14% 3	460
	21st to end	Day	10% 10% 37% 31% 11% 1	270
December	1st to 10th	Day	10% 13% 31% 28% 17% 2	270
	11th to 20th	Day	16% 13% 34% 31% 5% 1	270
	21st to end	Day	15% 11% 31% 31% 11% 2	297
January	1st to 10th	Night	15% 12% 33% 30% 10% 1	760
	11th to 20th	Night	12% 12% 28% 36% 11% 1	760
	21st to end	Night	17% 11% 36% 30% 6%	836
February	1st to 10th	Night	16% 9% 31% 34% 10%	760
	11th to 20th	Night	15% 11% 32% 34% 7%	743
	21st to end	Night	14% 10% 35% 35% 6%	628
March	1st to 10th	Night	10% 10% 31% 39% 9%	760
	11th to 20th	Night	11% 10% 34% 34% 11% 1	760
	21st to end	Night	11% 8% 32% 36% 13% 1	836
April	1st to 10th	Night	9% 8% 33% 38% 12% 1	729
	11th to 20th	Night	10% 9% 29% 34% 18% 1	711
	21st to end	Night	7% 4 27% 43% 17% 1	698
May	1st to 10th	Night	6% 3 21% 46% 23% 1	540
	11th to 20th	Night	7% 2 16% 38% 33% 4	531
	21st to end	Night	7% 1 10% 33% 42% 8%	584
June	1st to 10th	Night	14% 2 9% 33% 36% 6%	540
	11th to 20th	Night	6% 1 8% 28% 41% 15%	540
	21st to end	Night	8% 2 7% 25% 44% 15%	540
July	1st to 10th	Night	6% 2 6% 23% 44% 18%	525
	11th to 20th	Night	6% 1 3 18% 50% 21%	522
	21st to end	Night	4 1 4 22% 56% 12%	591
August	1st to 10th	Night	5% 6% 20% 52% 16%	537
	11th to 20th	Night	5% 1 4 19% 51% 20%	534
	21st to end	Night	12% 1 9% 22% 40% 17%	781
September	1st to 10th	Night	11% 2 6% 23% 45% 13%	720
	11th to 20th	Night	13% 3 8% 29% 37% 10%	720
	21st to end	Night	12% 2 11% 28% 37% 10%	720
October	1st to 10th	Night	12% 3 17% 33% 30% 4	720
	11th to 20th	Night	9% 5% 15% 37% 30% 4	720
	21st to end	Night	10% 4 20% 37% 28% 3	792
November	1st to 10th	Night	13% 5% 25% 33% 23% 2	740
	11th to 20th	Night	13% 7% 25% 33% 20% 1	760
	21st to end	Night	13% 7% 29% 34% 18% 1	760
December	1st to 10th	Night	14% 8% 25% 31% 20% 2	760
	11th to 20th	Night	14% 9% 25% 33% 16% 2	760
	21st to end	Night	15% 10% 25% 36% 14%	836

Page generated at 2024-03-31 06:08:50. Version ac07

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