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 2024-12-24.

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	13% 6% 2 6% 5% 5% 5% 4 6% 8% 40%	100955
	Night	13% 6% 2 6% 4 4 4 4 6% 8% 43%	99078
Transparency	Day	39% 8% 13% 19% 16% 5%	104598
	Night	38% 7% 12% 19% 17% 6%	103574
Seeing	Day	16% 12% 27% 25% 14% 5%	15641
	Night	15% 10% 26% 30% 16% 2	25783

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	15% 6% 2 4 3 3 3 2 5% 6% 51%	2836
	11th to 20th	Day	11% 5% 3 6% 3 3 3 4 5% 6% 51%	2840
	21st to end	Day	15% 8% 3 6% 5% 4 4 3 5% 6% 42%	3124
February	1st to 10th	Day	15% 7% 2 5% 4 5% 4 3 5% 7% 42%	1710
	11th to 20th	Day	19% 6% 3 6% 3 3 3 2 4 6% 45%	1793
	21st to end	Day	15% 6% 3 6% 5% 3 5% 4 5% 7% 41%	1615
March	1st to 10th	Day	24% 9% 2 5% 3 3 3 3 4 6% 36%	3435
	11th to 20th	Day	10% 4 2 5% 4 3 3 3 5% 8% 53%	3480
	21st to end	Day	17% 6% 2 6% 4 3 3 3 5% 5% 46%	3815
April	1st to 10th	Day	12% 6% 2 4 4 3 3 3 5% 6% 53%	2280
	11th to 20th	Day	10% 4 2 5% 4 3 4 4 6% 8% 50%	2254
	21st to end	Day	10% 4 1 5% 4 4 4 3 5% 7% 51%	2280
May	1st to 10th	Day	8% 6% 2 7% 5% 6% 6% 6% 7% 9% 38%	3765
	11th to 20th	Day	17% 7% 3 8% 5% 5% 5% 4 6% 7% 33%	4047
	21st to end	Day	7% 5% 2 6% 5% 6% 5% 5% 8% 11% 42%	4476
June	1st to 10th	Day	12% 6% 3 8% 6% 5% 6% 5% 8% 9% 34%	2602
	11th to 20th	Day	9% 5% 2 6% 4 5% 6% 6% 9% 11% 38%	2660
	21st to end	Day	9% 5% 2 6% 6% 7% 7% 6% 9% 12% 31%	2480
July	1st to 10th	Day	8% 5% 2 7% 5% 6% 6% 6% 9% 14% 32%	4120
	11th to 20th	Day	8% 8% 3 9% 7% 7% 7% 7% 8% 11% 23%	4120
	21st to end	Day	9% 8% 3 9% 7% 7% 7% 6% 9% 10% 24%	4466
August	1st to 10th	Day	22% 12% 4 8% 5% 5% 5% 5% 7% 9% 19%	4083
	11th to 20th	Day	9% 6% 3 9% 5% 6% 6% 5% 7% 10% 33%	3730
	21st to end	Day	7% 6% 2 6% 5% 5% 6% 5% 7% 10% 41%	4180
September	1st to 10th	Day	10% 7% 2 7% 6% 4 6% 5% 8% 10% 36%	2280
	11th to 20th	Day	15% 8% 2 7% 5% 5% 5% 5% 6% 8% 34%	2280
	21st to end	Day	16% 8% 3 8% 4 4 4 4 6% 6% 36%	1987
October	1st to 10th	Day	16% 7% 3 6% 4 3 4 3 4 6% 44%	1900
	11th to 20th	Day	11% 5% 2 5% 4 3 3 2 4 6% 55%	1900
	21st to end	Day	12% 5% 1 5% 3 3 4 3 5% 5% 55%	2090
November	1st to 10th	Day	13% 5% 2 4 4 3 4 3 5% 6% 52%	1957
	11th to 20th	Day	13% 7% 2 4 4 4 3 3 4 6% 51%	1934
	21st to end	Day	11% 5% 2 5% 5% 4 4 2 5% 7% 50%	1765
December	1st to 10th	Day	14% 7% 3 6% 4 4 5% 4 5% 7% 40%	1600
	11th to 20th	Day	16% 6% 2 4 3 3 2 3 3 5% 52%	1990
	21st to end	Day	14% 7% 3 6% 3 4 3 3 5% 6% 45%	3081
January	1st to 10th	Night	14% 6% 2 6% 4 4 3 3 4 6% 46%	4109
	11th to 20th	Night	14% 6% 2 7% 4 4 5% 4 6% 7% 42%	4120
	21st to end	Night	16% 7% 2 6% 4 4 4 3 5% 5% 43%	4532
February	1st to 10th	Night	18% 6% 2 4 4 4 4 3 5% 6% 44%	2470
	11th to 20th	Night	19% 8% 2 6% 4 3 3 3 5% 6% 40%	2270
	21st to end	Night	15% 6% 2 6% 4 4 4 4 5% 6% 41%	1836
March	1st to 10th	Night	25% 11% 3 6% 4 4 3 3 4 5% 32%	3418
	11th to 20th	Night	13% 6% 2 6% 3 4 4 3 6% 6% 48%	3480
	21st to end	Night	16% 5% 2 4 3 3 3 3 5% 6% 50%	3817
April	1st to 10th	Night	11% 5% 2 6% 4 4 4 3 6% 6% 49%	1900
	11th to 20th	Night	11% 5% 2 5% 4 4 4 4 4 7% 50%	1875
	21st to end	Night	8% 4 1 4 4 5% 4 3 6% 7% 54%	1900
May	1st to 10th	Night	8% 6% 2 7% 6% 5% 6% 5% 6% 9% 41%	3130
	11th to 20th	Night	16% 6% 3 8% 5% 4 5% 4 5% 7% 37%	2860
	21st to end	Night	8% 4 2 6% 4 5% 4 5% 6% 11% 45%	3079
June	1st to 10th	Night	9% 7% 2 8% 5% 5% 5% 4 7% 9% 39%	1568
	11th to 20th	Night	9% 5% 2 5% 4 5% 3 5% 7% 12% 43%	1520
	21st to end	Night	10% 7% 2 6% 5% 4 5% 4 7% 12% 37%	1686
July	1st to 10th	Night	7% 5% 2 8% 5% 6% 6% 5% 7% 13% 35%	2840
	11th to 20th	Night	8% 7% 3 9% 7% 6% 6% 6% 9% 12% 28%	2840
	21st to end	Night	9% 7% 3 8% 6% 6% 6% 6% 10% 11% 28%	3087
August	1st to 10th	Night	17% 11% 4 8% 5% 5% 6% 4 7% 10% 23%	2825
	11th to 20th	Night	8% 6% 3 8% 6% 6% 6% 6% 8% 10% 35%	3088
	21st to end	Night	7% 5% 2 6% 5% 5% 5% 5% 8% 9% 43%	3476
September	1st to 10th	Night	11% 5% 1 6% 5% 4 5% 4 7% 9% 43%	1900
	11th to 20th	Night	13% 6% 3 7% 4 4 5% 4 5% 7% 40%	1900
	21st to end	Night	16% 8% 3 7% 4 4 4 3 5% 6% 38%	2186
October	1st to 10th	Night	14% 6% 2 5% 4 4 3 3 4 6% 48%	2280
	11th to 20th	Night	10% 5% 2 5% 3 3 3 3 4 6% 55%	2280
	21st to end	Night	11% 5% 2 5% 3 3 3 3 4 6% 56%	2508
November	1st to 10th	Night	12% 6% 2 5% 3 4 4 3 5% 6% 51%	2341
	11th to 20th	Night	14% 7% 3 6% 4 3 3 3 4 6% 48%	2463
	21st to end	Night	11% 6% 2 5% 4 4 3 3 4 7% 51%	2630
December	1st to 10th	Night	15% 7% 3 6% 4 4 3 3 5% 7% 43%	2800
	11th to 20th	Night	16% 6% 2 5% 4 3 3 4 4 6% 47%	3425
	21st to end	Night	15% 6% 2 6% 3 4 3 2 5% 6% 48%	4639

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	35% 4 9% 21% 26% 6%	2837
	11th to 20th	Day	34% 4 7% 20% 26% 10%	2840
	21st to end	Day	44% 6% 7% 15% 19% 10%	3124
February	1st to 10th	Day	42% 4 10% 20% 18% 5%	1710
	11th to 20th	Day	43% 4 7% 16% 23% 7%	1802
	21st to end	Day	42% 6% 10% 18% 16% 8%	1615
March	1st to 10th	Day	49% 5% 10% 14% 14% 7%	3435
	11th to 20th	Day	30% 5% 11% 17% 25% 13%	3480
	21st to end	Day	40% 4 7% 24% 17% 6%	3815
April	1st to 10th	Day	32% 6% 10% 22% 23% 7%	2280
	11th to 20th	Day	31% 6% 12% 22% 19% 9%	2254
	21st to end	Day	31% 7% 14% 23% 21% 4	2280
May	1st to 10th	Day	37% 12% 19% 20% 10% 2	3800
	11th to 20th	Day	47% 8% 11% 19% 13% 1	4051
	21st to end	Day	32% 11% 17% 26% 13% 1	4489
June	1st to 10th	Day	43% 10% 15% 20% 11% 1	2602
	11th to 20th	Day	35% 12% 19% 22% 11% 1	2660
	21st to end	Day	40% 13% 18% 20% 8% 1	2480
July	1st to 10th	Day	36% 14% 25% 19% 5% 1	4055
	11th to 20th	Day	48% 16% 21% 11% 4	4051
	21st to end	Day	49% 13% 17% 15% 6%	4324
August	1st to 10th	Day	59% 11% 18% 9% 3	4070
	11th to 20th	Day	42% 12% 15% 21% 10%	3766
	21st to end	Day	36% 10% 18% 28% 8% 1	4180
September	1st to 10th	Day	40% 13% 16% 14% 13% 4	2280
	11th to 20th	Day	46% 9% 11% 16% 15% 3	2280
	21st to end	Day	46% 7% 12% 16% 15% 3	1987
October	1st to 10th	Day	38% 5% 8% 20% 24% 5%	3160
	11th to 20th	Day	23% 3 6% 19% 24% 26%	3140
	21st to end	Day	26% 5% 7% 23% 29% 10%	3428
November	1st to 10th	Day	33% 6% 8% 19% 26% 8%	1957
	11th to 20th	Day	37% 4 8% 19% 25% 8%	1934
	21st to end	Day	35% 5% 8% 22% 24% 7%	1765
December	1st to 10th	Day	43% 6% 10% 20% 15% 6%	1600
	11th to 20th	Day	36% 4 7% 20% 24% 9%	1986
	21st to end	Day	40% 4 10% 21% 22% 2	3081
January	1st to 10th	Night	38% 4 9% 21% 22% 6%	4109
	11th to 20th	Night	40% 5% 8% 17% 23% 6%	4120
	21st to end	Night	42% 5% 7% 16% 21% 8%	4532
February	1st to 10th	Night	41% 4 10% 18% 20% 6%	2470
	11th to 20th	Night	45% 4 9% 16% 19% 7%	2272
	21st to end	Night	42% 6% 10% 16% 18% 8%	1836
March	1st to 10th	Night	55% 6% 8% 14% 13% 5%	3418
	11th to 20th	Night	36% 6% 9% 11% 23% 15%	3480
	21st to end	Night	35% 4 11% 25% 18% 6%	3817
April	1st to 10th	Night	34% 5% 13% 17% 23% 7%	1900
	11th to 20th	Night	33% 6% 13% 21% 18% 8%	1875
	21st to end	Night	28% 7% 14% 28% 18% 4	1900
May	1st to 10th	Night	36% 11% 19% 22% 10% 2	3160
	11th to 20th	Night	44% 8% 13% 22% 13%	2861
	21st to end	Night	30% 11% 21% 24% 13% 1	3087
June	1st to 10th	Night	41% 7% 17% 24% 10% 1	1568
	11th to 20th	Night	33% 10% 19% 28% 9% 1	1520
	21st to end	Night	39% 10% 19% 23% 8% 1	1686
July	1st to 10th	Night	38% 13% 23% 20% 5%	2795
	11th to 20th	Night	44% 13% 27% 12% 4	2786
	21st to end	Night	45% 17% 16% 16% 6%	2988
August	1st to 10th	Night	54% 12% 20% 12% 2	2814
	11th to 20th	Night	38% 14% 19% 20% 7%	3118
	21st to end	Night	32% 11% 17% 31% 8% 1	3476
September	1st to 10th	Night	36% 11% 20% 16% 14% 3	1900
	11th to 20th	Night	42% 9% 12% 20% 14% 3	1900
	21st to end	Night	46% 8% 12% 18% 14% 2	2186
October	1st to 10th	Night	41% 6% 7% 18% 23% 4	3800
	11th to 20th	Night	21% 3 6% 17% 21% 33%	3779
	21st to end	Night	24% 4 8% 25% 28% 10%	4120
November	1st to 10th	Night	34% 6% 9% 17% 25% 8%	2341
	11th to 20th	Night	38% 4 8% 15% 26% 8%	2463
	21st to end	Night	33% 5% 8% 23% 24% 7%	2630
December	1st to 10th	Night	41% 6% 11% 16% 19% 5%	2800
	11th to 20th	Night	38% 4 8% 18% 24% 7%	3428
	21st to end	Night	39% 4 8% 23% 23% 3	4639

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	21% 28% 37% 11% 3	270
	11th to 20th	Day	18% 26% 40% 14% 3	270
	21st to end	Day	22% 29% 32% 14% 2	297
February	1st to 10th	Day	25% 19% 40% 14% 2	270
	11th to 20th	Day	29% 24% 31% 13% 2	401
	21st to end	Day	22% 24% 34% 15% 4 1	382
March	1st to 10th	Day	22% 19% 37% 17% 6%	460
	11th to 20th	Day	23% 24% 35% 12% 5% 1	460
	21st to end	Day	21% 20% 36% 14% 7% 1	506
April	1st to 10th	Day	23% 22% 30% 17% 7% 1	460
	11th to 20th	Day	15% 19% 33% 20% 8% 5%	452
	21st to end	Day	15% 15% 33% 24% 10% 3	460
May	1st to 10th	Day	13% 19% 34% 21% 10% 4	463
	11th to 20th	Day	17% 10% 28% 29% 11% 4	487
	21st to end	Day	15% 6% 22% 30% 18% 8%	529
June	1st to 10th	Day	10% 6% 29% 34% 17% 4	490
	11th to 20th	Day	12% 4 22% 34% 17% 10%	490
	21st to end	Day	9% 4 24% 36% 20% 7%	490
July	1st to 10th	Day	11% 2 14% 38% 26% 9%	485
	11th to 20th	Day	10% 4 15% 35% 28% 9%	484
	21st to end	Day	9% 3 20% 38% 22% 7%	532
August	1st to 10th	Day	17% 5% 19% 30% 21% 10%	486
	11th to 20th	Day	13% 3 18% 29% 24% 13%	479
	21st to end	Day	11% 4 16% 31% 24% 14%	539
September	1st to 10th	Day	13% 3 20% 31% 20% 13%	490
	11th to 20th	Day	20% 7% 20% 29% 16% 8%	490
	21st to end	Day	19% 6% 23% 27% 17% 7%	490
October	1st to 10th	Day	18% 6% 26% 27% 16% 7%	490
	11th to 20th	Day	12% 11% 27% 31% 14% 5%	490
	21st to end	Day	13% 11% 27% 28% 17% 4	539
November	1st to 10th	Day	18% 10% 31% 27% 12% 3	495
	11th to 20th	Day	15% 20% 32% 24% 9% 1	466
	21st to end	Day	14% 16% 32% 21% 16% 2	365
December	1st to 10th	Day	18% 23% 37% 17% 6%	200
	11th to 20th	Day	21% 18% 35% 17% 9% 1	200
	21st to end	Day	20% 18% 36% 17% 9% 1	284
January	1st to 10th	Night	18% 20% 32% 23% 7%	760
	11th to 20th	Night	18% 16% 29% 30% 7%	760
	21st to end	Night	19% 17% 35% 26% 3	836
February	1st to 10th	Night	22% 14% 34% 24% 5%	760
	11th to 20th	Night	24% 19% 35% 21% 2	743
	21st to end	Night	20% 19% 32% 24% 6%	628
March	1st to 10th	Night	17% 16% 37% 25% 5%	760
	11th to 20th	Night	19% 15% 37% 22% 6% 1	760
	21st to end	Night	17% 14% 37% 24% 7%	836
April	1st to 10th	Night	14% 18% 36% 25% 6%	760
	11th to 20th	Night	14% 12% 34% 27% 11% 1	751
	21st to end	Night	10% 11% 38% 32% 8% 1	760
May	1st to 10th	Night	11% 12% 36% 31% 9% 1	760
	11th to 20th	Night	17% 8% 26% 36% 13% 1	596
	21st to end	Night	11% 3 16% 36% 29% 5%	617
June	1st to 10th	Night	11% 2 22% 43% 18% 3	428
	11th to 20th	Night	10% 3 18% 40% 24% 4	380
	21st to end	Night	13% 3 16% 42% 24% 3	546
July	1st to 10th	Night	7% 2 13% 40% 33% 5%	555
	11th to 20th	Night	8% 2 11% 36% 36% 8%	552
	21st to end	Night	8% 2 13% 42% 31% 4	624
August	1st to 10th	Night	11% 2 14% 32% 34% 7%	567
	11th to 20th	Night	10% 2 13% 39% 29% 7%	741
	21st to end	Night	13% 2 13% 32% 32% 8%	836
September	1st to 10th	Night	14% 3 14% 32% 31% 7%	760
	11th to 20th	Night	16% 2 17% 36% 23% 6%	760
	21st to end	Night	21% 4 19% 29% 24% 4	760
October	1st to 10th	Night	17% 5% 21% 29% 22% 6%	760
	11th to 20th	Night	13% 7% 28% 31% 18% 3	760
	21st to end	Night	14% 7% 25% 32% 19% 3	836
November	1st to 10th	Night	14% 8% 28% 33% 14% 2	780
	11th to 20th	Night	19% 12% 30% 26% 12% 2	800
	21st to end	Night	14% 12% 30% 29% 14% 1	800
December	1st to 10th	Night	20% 14% 29% 29% 8% 1	800
	11th to 20th	Night	18% 13% 28% 30% 10% 1	800
	21st to end	Night	19% 14% 30% 29% 8% 1	851

Page generated at 2024-12-21 04:13:46. Version ac07

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