Naples
Clear Sky Chart
History

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

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	6% 5% 2 6% 5% 5% 6% 5% 8% 11% 41%	100698
	Night	6% 5% 2 7% 5% 5% 6% 5% 7% 10% 41%	98264
Transparency	Day	33% 11% 21% 21% 11% 3	104473
	Night	35% 10% 19% 20% 12% 3	102615
Seeing	Day	6% 3 13% 27% 32% 19%	15701
	Night	7% 3 14% 32% 31% 13%	25774

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	10% 8% 3 5% 4 4 4 3 6% 10% 42%	2836
	11th to 20th	Day	16% 7% 3 8% 6% 4 5% 5% 6% 8% 32%	2840
	21st to end	Day	7% 6% 3 8% 5% 6% 5% 5% 7% 7% 43%	3414
February	1st to 10th	Day	8% 6% 2 5% 4 4 4 3 7% 9% 48%	1900
	11th to 20th	Day	6% 3 1 3 3 4 3 3 6% 8% 61%	1848
	21st to end	Day	5% 3 2 4 3 3 4 5% 6% 8% 58%	1704
March	1st to 10th	Day	5% 3 2 8% 5% 5% 5% 6% 9% 11% 43%	3435
	11th to 20th	Day	3 2 1 4 3 3 4 4 7% 11% 57%	3480
	21st to end	Day	8% 4 2 4 3 3 3 4 5% 8% 56%	3815
April	1st to 10th	Day	3 3 1 3 3 3 4 4 8% 10% 59%	2090
	11th to 20th	Day	5% 4 2 5% 3 4 4 4 6% 9% 56%	2066
	21st to end	Day	4 4 1 4 3 4 4 3 7% 9% 56%	2251
May	1st to 10th	Day	2 1 1 2 2 2 3 3 5% 8% 72%	3846
	11th to 20th	Day	5% 4 2 4 4 4 5% 4 7% 11% 50%	4081
	21st to end	Day	5% 4 1 4 3 3 4 4 5% 8% 59%	4476
June	1st to 10th	Day	10% 8% 3 7% 6% 6% 7% 6% 8% 10% 28%	2470
	11th to 20th	Day	7% 5% 2 7% 6% 8% 7% 7% 9% 13% 28%	2470
	21st to end	Day	5% 6% 2 8% 7% 7% 8% 8% 12% 12% 26%	2470
July	1st to 10th	Day	5% 5% 3 8% 7% 7% 9% 7% 10% 14% 27%	4120
	11th to 20th	Day	3 4 2 8% 7% 8% 10% 8% 12% 13% 25%	4120
	21st to end	Day	4 3 2 7% 6% 7% 8% 8% 11% 15% 29%	4466
August	1st to 10th	Day	4 4 3 10% 8% 8% 8% 7% 9% 12% 26%	4078
	11th to 20th	Day	3 3 2 7% 6% 8% 9% 8% 11% 13% 29%	3553
	21st to end	Day	4 5% 2 8% 7% 8% 9% 7% 11% 13% 26%	3828
September	1st to 10th	Day	4 5% 3 8% 8% 8% 7% 7% 10% 12% 29%	2090
	11th to 20th	Day	6% 6% 3 8% 7% 7% 9% 7% 9% 11% 27%	2090
	21st to end	Day	8% 8% 3 8% 7% 7% 7% 6% 8% 11% 26%	2090
October	1st to 10th	Day	7% 5% 3 7% 5% 6% 7% 6% 9% 11% 33%	2090
	11th to 20th	Day	6% 5% 2 7% 5% 5% 8% 4 8% 11% 38%	1917
	21st to end	Day	7% 5% 3 6% 4 4 6% 5% 6% 8% 47%	2090
November	1st to 10th	Day	5% 4 2 5% 4 4 5% 4 6% 10% 51%	1887
	11th to 20th	Day	8% 5% 1 4 5% 5% 6% 6% 7% 9% 44%	1900
	21st to end	Day	5% 4 2 6% 5% 4 4 5% 8% 9% 49%	1900
December	1st to 10th	Day	8% 5% 2 4 4 3 4 4 6% 9% 51%	1710
	11th to 20th	Day	7% 5% 2 5% 4 5% 5% 4 6% 10% 47%	2153
	21st to end	Day	9% 6% 3 6% 5% 5% 6% 5% 8% 9% 38%	3124
January	1st to 10th	Night	7% 6% 2 8% 6% 5% 5% 5% 7% 11% 38%	4109
	11th to 20th	Night	15% 9% 4 9% 5% 5% 5% 4 7% 8% 28%	4120
	21st to end	Night	6% 6% 3 8% 5% 5% 6% 4 8% 8% 40%	4238
February	1st to 10th	Night	7% 7% 2 6% 5% 4 5% 3 6% 8% 47%	2280
	11th to 20th	Night	6% 5% 2 4 4 4 3 4 5% 8% 56%	2218
	21st to end	Night	3 3 1 5% 3 3 4 3 6% 8% 61%	1747
March	1st to 10th	Night	6% 5% 2 9% 5% 6% 6% 4 7% 8% 42%	3418
	11th to 20th	Night	5% 4 1 4 3 4 4 4 7% 10% 55%	3480
	21st to end	Night	7% 4 1 5% 4 4 4 4 6% 8% 53%	3817
April	1st to 10th	Night	5% 3 1 4 3 3 3 5% 6% 10% 57%	2090
	11th to 20th	Night	5% 3 1 6% 4 4 4 4 7% 11% 52%	2063
	21st to end	Night	4 4 2 4 4 3 5% 4 6% 9% 55%	1927
May	1st to 10th	Night	6% 4 1 4 4 4 4 4 5% 8% 55%	3076
	11th to 20th	Night	5% 3 1 4 3 4 4 4 7% 8% 57%	2812
	21st to end	Night	4 4 1 4 3 4 4 3 6% 8% 59%	3079
June	1st to 10th	Night	11% 7% 3 8% 6% 6% 6% 6% 8% 11% 29%	1710
	11th to 20th	Night	7% 7% 2 6% 6% 5% 7% 5% 8% 13% 33%	1710
	21st to end	Night	5% 5% 2 9% 7% 8% 7% 6% 9% 13% 29%	1710
July	1st to 10th	Night	3 5% 2 10% 9% 8% 8% 7% 9% 12% 27%	2840
	11th to 20th	Night	4 6% 3 9% 7% 7% 9% 7% 12% 12% 23%	2840
	21st to end	Night	3 6% 2 8% 7% 9% 8% 8% 11% 13% 24%	3087
August	1st to 10th	Night	4 5% 2 9% 7% 7% 8% 7% 10% 13% 27%	2846
	11th to 20th	Night	5% 5% 3 9% 7% 7% 8% 7% 10% 13% 25%	3227
	21st to end	Night	5% 5% 3 8% 7% 7% 8% 6% 10% 15% 24%	3828
September	1st to 10th	Night	5% 4 2 7% 6% 7% 8% 7% 10% 16% 28%	2090
	11th to 20th	Night	6% 6% 2 8% 6% 7% 7% 6% 9% 13% 29%	2090
	21st to end	Night	8% 7% 3 10% 6% 6% 7% 6% 8% 11% 27%	2090
October	1st to 10th	Night	8% 6% 3 8% 5% 5% 6% 5% 7% 11% 36%	2090
	11th to 20th	Night	7% 7% 2 6% 5% 5% 5% 4 6% 9% 44%	2261
	21st to end	Night	8% 5% 2 7% 5% 5% 5% 4 6% 9% 43%	2508
November	1st to 10th	Night	7% 5% 2 5% 4 4 5% 3 7% 8% 52%	2264
	11th to 20th	Night	6% 7% 3 5% 5% 4 4 4 5% 9% 48%	2280
	21st to end	Night	7% 5% 2 5% 5% 5% 4 5% 6% 9% 45%	2280
December	1st to 10th	Night	6% 5% 2 5% 4 4 5% 4 6% 9% 52%	2465
	11th to 20th	Night	9% 6% 2 5% 4 3 4 4 6% 8% 50%	3042
	21st to end	Night	9% 7% 3 7% 5% 5% 5% 5% 8% 10% 36%	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% 7% 12% 23% 16% 4	2837
	11th to 20th	Day	46% 9% 12% 18% 11% 3	2840
	21st to end	Day	36% 7% 11% 23% 18% 5%	3414
February	1st to 10th	Day	31% 6% 14% 24% 20% 6%	1900
	11th to 20th	Day	20% 5% 13% 28% 23% 10%	1858
	21st to end	Day	23% 6% 14% 21% 29% 7%	1704
March	1st to 10th	Day	30% 11% 17% 23% 16% 4	3435
	11th to 20th	Day	18% 8% 25% 31% 15% 4	3480
	21st to end	Day	24% 6% 13% 32% 17% 9%	3815
April	1st to 10th	Day	18% 7% 21% 33% 16% 5%	2090
	11th to 20th	Day	24% 8% 19% 28% 17% 4	2066
	21st to end	Day	22% 6% 16% 27% 24% 4	2251
May	1st to 10th	Day	9% 5% 18% 39% 24% 3	3881
	11th to 20th	Day	24% 10% 22% 35% 9% 1	4085
	21st to end	Day	21% 8% 17% 38% 15% 1	4489
June	1st to 10th	Day	44% 14% 23% 16% 2	2470
	11th to 20th	Day	40% 17% 27% 14% 2	2470
	21st to end	Day	41% 19% 28% 11% 1	2470
July	1st to 10th	Day	42% 15% 32% 10%	4055
	11th to 20th	Day	44% 17% 33% 6%	4051
	21st to end	Day	38% 19% 32% 11%	4324
August	1st to 10th	Day	45% 16% 29% 8% 2	4065
	11th to 20th	Day	37% 17% 35% 12%	3589
	21st to end	Day	43% 16% 34% 7% 1	3828
September	1st to 10th	Day	42% 20% 28% 11%	2090
	11th to 20th	Day	43% 19% 22% 13% 3	2090
	21st to end	Day	47% 15% 20% 12% 5% 1	2090
October	1st to 10th	Day	46% 11% 20% 14% 7% 2	3480
	11th to 20th	Day	35% 8% 20% 21% 13% 2	3157
	21st to end	Day	31% 5% 12% 29% 19% 5%	3428
November	1st to 10th	Day	27% 8% 16% 20% 18% 11%	1887
	11th to 20th	Day	33% 8% 13% 23% 16% 8%	1900
	21st to end	Day	27% 8% 16% 23% 21% 5%	1900
December	1st to 10th	Day	29% 6% 15% 27% 19% 3	1710
	11th to 20th	Day	29% 7% 15% 22% 17% 9%	2150
	21st to end	Day	38% 9% 16% 19% 15% 3	3124
January	1st to 10th	Night	36% 9% 13% 21% 17% 3	4109
	11th to 20th	Night	52% 9% 11% 16% 9% 3	4120
	21st to end	Night	37% 7% 11% 21% 20% 4	4238
February	1st to 10th	Night	33% 7% 13% 22% 19% 6%	2280
	11th to 20th	Night	26% 6% 12% 24% 21% 10%	2219
	21st to end	Night	20% 5% 13% 23% 30% 8%	1747
March	1st to 10th	Night	36% 10% 13% 23% 14% 4	3418
	11th to 20th	Night	23% 8% 21% 29% 17% 3	3480
	21st to end	Night	26% 8% 13% 25% 22% 7%	3817
April	1st to 10th	Night	21% 7% 19% 33% 16% 4	2090
	11th to 20th	Night	25% 8% 18% 26% 20% 4	2063
	21st to end	Night	23% 8% 16% 26% 23% 4	1927
May	1st to 10th	Night	22% 10% 17% 33% 15% 3	3106
	11th to 20th	Night	21% 9% 22% 38% 10%	2813
	21st to end	Night	20% 9% 16% 36% 18% 1	3087
June	1st to 10th	Night	45% 13% 20% 19% 3	1710
	11th to 20th	Night	39% 14% 28% 16% 2	1710
	21st to end	Night	42% 16% 28% 11% 2	1710
July	1st to 10th	Night	46% 15% 29% 9%	2795
	11th to 20th	Night	47% 16% 31% 6%	2786
	21st to end	Night	44% 18% 26% 12%	2988
August	1st to 10th	Night	42% 16% 30% 11% 2	2835
	11th to 20th	Night	45% 15% 31% 8%	3257
	21st to end	Night	44% 18% 33% 4 1	3828
September	1st to 10th	Night	37% 20% 31% 11% 1	2090
	11th to 20th	Night	41% 18% 25% 13% 2	2090
	21st to end	Night	46% 17% 19% 13% 5% 1	2090
October	1st to 10th	Night	52% 10% 19% 12% 6% 2	3480
	11th to 20th	Night	39% 7% 17% 21% 15% 2	3747
	21st to end	Night	34% 7% 11% 26% 18% 4	4120
November	1st to 10th	Night	28% 8% 14% 21% 21% 8%	2264
	11th to 20th	Night	32% 8% 13% 23% 19% 7%	2280
	21st to end	Night	31% 8% 14% 20% 22% 4	2280
December	1st to 10th	Night	28% 7% 17% 28% 17% 4	2465
	11th to 20th	Night	30% 7% 12% 24% 19% 9%	3044
	21st to end	Night	37% 9% 21% 17% 14% 3	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	7% 5% 31% 36% 18% 3	270
	11th to 20th	Day	10% 10% 26% 30% 21% 3	270
	21st to end	Day	11% 7% 31% 40% 9% 1	297
February	1st to 10th	Day	4 9% 22% 41% 23% 3	270
	11th to 20th	Day	6% 4 22% 41% 22% 5%	270
	21st to end	Day	3 4 23% 39% 28% 3	359
March	1st to 10th	Day	3 4 25% 48% 19% 1	460
	11th to 20th	Day	4 4 23% 38% 28% 2	460
	21st to end	Day	4 3 22% 43% 26% 3	506
April	1st to 10th	Day	3 5% 25% 44% 20% 3	460
	11th to 20th	Day	5% 6% 23% 36% 26% 3	452
	21st to end	Day	4 3 15% 41% 34% 3	460
May	1st to 10th	Day	2 12% 42% 36% 8%	463
	11th to 20th	Day	6% 3 13% 34% 33% 11%	487
	21st to end	Day	7% 1 7% 25% 39% 21%	529
June	1st to 10th	Day	13% 1 7% 19% 39% 19%	490
	11th to 20th	Day	9% 1 7% 18% 35% 31%	490
	21st to end	Day	3 1 2 11% 36% 47%	490
July	1st to 10th	Day	5% 1 1 7% 36% 50%	485
	11th to 20th	Day	5% 2 7% 35% 51%	484
	21st to end	Day	6% 2 2 12% 35% 44%	532
August	1st to 10th	Day	5% 1 2 12% 37% 44%	486
	11th to 20th	Day	5% 1 2 8% 41% 44%	479
	21st to end	Day	8% 1 4 15% 36% 35%	539
September	1st to 10th	Day	5% 2 3 10% 36% 44%	490
	11th to 20th	Day	6% 1 4 15% 38% 37%	490
	21st to end	Day	7% 2 5% 15% 38% 33%	490
October	1st to 10th	Day	9% 1 10% 28% 37% 14%	490
	11th to 20th	Day	7% 3 13% 27% 36% 14%	490
	21st to end	Day	9% 3 12% 33% 33% 9%	539
November	1st to 10th	Day	7% 4 16% 29% 36% 9%	467
	11th to 20th	Day	10% 3 19% 32% 28% 7%	460
	21st to end	Day	3 2 20% 38% 33% 4	460
December	1st to 10th	Day	9% 4 16% 35% 29% 7%	270
	11th to 20th	Day	7% 4 21% 34% 27% 6%	270
	21st to end	Day	5% 5% 21% 33% 31% 6%	297
January	1st to 10th	Night	8% 6% 21% 40% 24% 2	760
	11th to 20th	Night	9% 6% 24% 38% 22% 1	760
	21st to end	Night	8% 6% 29% 41% 16%	836
February	1st to 10th	Night	8% 5% 26% 42% 19% 1	760
	11th to 20th	Night	7% 6% 22% 41% 23% 2	743
	21st to end	Night	5% 3 17% 48% 27% 1	628
March	1st to 10th	Night	4 5% 22% 46% 22% 1	760
	11th to 20th	Night	8% 2 21% 42% 26% 1	760
	21st to end	Night	4 4 22% 47% 23% 1	836
April	1st to 10th	Night	5% 3 19% 45% 27% 1	760
	11th to 20th	Night	5% 4 20% 47% 23% 1	751
	21st to end	Night	6% 2 18% 44% 28% 2	760
May	1st to 10th	Night	4 1 11% 44% 35% 4	732
	11th to 20th	Night	7% 2 12% 38% 36% 5%	561
	21st to end	Night	6% 1 7% 28% 48% 9%	617
June	1st to 10th	Night	12% 2 5% 19% 48% 14%	570
	11th to 20th	Night	7% 2 5% 17% 39% 30%	570
	21st to end	Night	5% 1 2 10% 41% 41%	570
July	1st to 10th	Night	4 2 2 7% 39% 46%	555
	11th to 20th	Night	4 1 2 9% 38% 45%	552
	21st to end	Night	4 1 2 8% 37% 48%	624
August	1st to 10th	Night	5% 1 2 11% 44% 37%	567
	11th to 20th	Night	7% 1 2 8% 36% 46%	639
	21st to end	Night	10% 2 5% 16% 37% 29%	836
September	1st to 10th	Night	6% 1 3 13% 43% 34%	760
	11th to 20th	Night	8% 2 3 17% 40% 29%	760
	21st to end	Night	12% 1 6% 22% 37% 22%	760
October	1st to 10th	Night	11% 2 9% 33% 34% 11%	760
	11th to 20th	Night	9% 3 11% 33% 35% 10%	760
	21st to end	Night	10% 2 16% 37% 27% 7%	836
November	1st to 10th	Night	8% 3 20% 36% 29% 3	755
	11th to 20th	Night	8% 3 19% 39% 27% 3	760
	21st to end	Night	8% 4 19% 39% 29% 1	760
December	1st to 10th	Night	8% 3 17% 40% 29% 3	760
	11th to 20th	Night	9% 4 19% 36% 28% 3	760
	21st to end	Night	8% 4 18% 39% 29% 2	836

Page generated at 2024-11-01 22:47:46. Version ac07

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