Parc National d'Aiguebelle
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Parc National d'Aiguebelle clear sky chart from 2005-11-06 to 2024-01-16.

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	19% 12% 4 8% 6% 4 5% 5% 5% 6% 26%	74739
	Night	18% 13% 6% 9% 7% 3 5% 4 4 5% 24%	75068
Transparency	Day	60% 4 10% 18% 8% 1	74432
	Night	63% 3 10% 16% 7% 1	74910
Seeing	Day	25% 13% 31% 20% 8% 2	13995
	Night	25% 11% 29% 25% 9% 1	23085

By Month

Percentage Cloud Cover NE (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% 21% 9% 14% 6% 5% 6% 5% 5% 4 11%	1328
	11th to 20th	Day	14% 16% 6% 14% 8% 4 6% 8% 6% 5% 13%	1295
	21st to end	Day	11% 15% 7% 12% 8% 6% 8% 6% 6% 6% 14%	1661
February	1st to 10th	Day	10% 14% 7% 10% 9% 7% 9% 5% 5% 6% 17%	1620
	11th to 20th	Day	11% 18% 6% 11% 8% 4 7% 6% 6% 6% 17%	1573
	21st to end	Day	12% 17% 6% 11% 8% 4 5% 5% 4 6% 23%	1332
March	1st to 10th	Day	14% 13% 6% 10% 8% 5% 6% 5% 5% 4 24%	1907
	11th to 20th	Day	15% 15% 5% 9% 7% 3 4 4 3 5% 29%	1980
	21st to end	Day	15% 14% 4 7% 6% 4 5% 4 4 5% 31%	2202
April	1st to 10th	Day	20% 15% 6% 8% 6% 3 5% 4 4 5% 23%	2160
	11th to 20th	Day	20% 11% 4 9% 5% 3 4 4 4 6% 31%	2258
	21st to end	Day	21% 13% 4 7% 5% 2 4 4 4 5% 31%	2340
May	1st to 10th	Day	17% 11% 4 7% 6% 3 5% 5% 5% 7% 31%	2520
	11th to 20th	Day	23% 10% 3 6% 5% 3 4 4 5% 5% 32%	2478
	21st to end	Day	20% 8% 3 5% 5% 3 4 4 5% 7% 35%	2765
June	1st to 10th	Day	24% 8% 3 5% 6% 3 5% 5% 5% 7% 30%	2700
	11th to 20th	Day	17% 7% 4 6% 5% 4 5% 5% 5% 7% 36%	2700
	21st to end	Day	21% 7% 3 6% 6% 3 4 5% 6% 7% 32%	2700
July	1st to 10th	Day	18% 6% 2 6% 5% 4 5% 5% 6% 9% 33%	2700
	11th to 20th	Day	17% 6% 2 6% 5% 4 6% 6% 7% 8% 33%	2700
	21st to end	Day	18% 6% 4 7% 6% 3 6% 6% 6% 8% 30%	2794
August	1st to 10th	Day	20% 7% 3 7% 7% 4 6% 5% 6% 8% 27%	2423
	11th to 20th	Day	19% 8% 3 6% 6% 4 5% 5% 5% 8% 31%	2303
	21st to end	Day	20% 6% 3 6% 6% 4 5% 5% 6% 8% 32%	2516
September	1st to 10th	Day	21% 7% 3 6% 5% 4 4 6% 5% 7% 32%	2160
	11th to 20th	Day	24% 9% 3 5% 5% 3 4 4 5% 8% 30%	2124
	21st to end	Day	26% 10% 3 5% 4 3 4 4 4 6% 30%	1904
October	1st to 10th	Day	24% 11% 3 7% 5% 2 4 4 4 6% 30%	1800
	11th to 20th	Day	32% 19% 4 6% 4 3 3 4 4 4 16%	1800
	21st to end	Day	29% 19% 5% 7% 6% 3 4 4 4 5% 14%	1852
November	1st to 10th	Day	22% 21% 6% 9% 7% 3 3 4 3 5% 17%	1486
	11th to 20th	Day	23% 17% 8% 13% 9% 5% 4 2 4 4 12%	1520
	21st to end	Day	26% 21% 9% 11% 8% 3 3 4 3 3 9%	1520
December	1st to 10th	Day	18% 21% 8% 15% 8% 3 4 4 4 5% 11%	1516
	11th to 20th	Day	18% 17% 7% 10% 10% 5% 6% 5% 4 3 15%	1671
	21st to end	Day	17% 21% 8% 16% 11% 3 5% 3 3 3 10%	2431
January	1st to 10th	Night	14% 20% 9% 14% 9% 4 6% 6% 3 4 11%	2838
	11th to 20th	Night	16% 17% 7% 11% 7% 4 6% 8% 6% 5% 13%	2788
	21st to end	Night	11% 13% 6% 13% 10% 6% 8% 6% 7% 5% 16%	2689
February	1st to 10th	Night	10% 16% 6% 9% 11% 5% 6% 6% 5% 7% 20%	2340
	11th to 20th	Night	12% 15% 7% 12% 9% 4 5% 4 4 6% 22%	2273
	21st to end	Night	9% 16% 6% 12% 9% 4 7% 5% 5% 7% 20%	1924
March	1st to 10th	Night	12% 13% 8% 10% 8% 5% 6% 5% 5% 5% 23%	2039
	11th to 20th	Night	17% 13% 6% 10% 7% 4 6% 4 4 4 23%	1979
	21st to end	Night	15% 12% 4 8% 5% 3 5% 4 4 6% 34%	2153
April	1st to 10th	Night	21% 15% 5% 8% 6% 3 3 3 4 4 29%	1800
	11th to 20th	Night	18% 8% 4 7% 6% 3 5% 6% 6% 5% 32%	1667
	21st to end	Night	20% 10% 4 7% 5% 3 3 3 4 6% 33%	1620
May	1st to 10th	Night	17% 10% 3 6% 6% 4 5% 4 5% 5% 36%	1440
	11th to 20th	Night	22% 8% 3 4 4 3 4 6% 6% 7% 34%	1415
	21st to end	Night	20% 6% 3 5% 5% 2 5% 5% 6% 7% 37%	1506
June	1st to 10th	Night	22% 7% 4 6% 7% 2 4 5% 4 6% 32%	1260
	11th to 20th	Night	16% 7% 3 5% 5% 3 4 3 5% 7% 41%	1260
	21st to end	Night	17% 4 3 6% 5% 3 5% 6% 5% 6% 39%	1260
July	1st to 10th	Night	18% 5% 3 5% 5% 3 5% 6% 6% 8% 37%	1260
	11th to 20th	Night	17% 6% 2 5% 5% 3 5% 6% 7% 8% 37%	1260
	21st to end	Night	15% 7% 2 6% 6% 4 4 5% 6% 8% 36%	1522
August	1st to 10th	Night	17% 7% 3 6% 5% 4 5% 5% 5% 7% 37%	1511
	11th to 20th	Night	14% 7% 2 6% 6% 3 5% 4 5% 8% 40%	1598
	21st to end	Night	19% 7% 2 6% 7% 4 5% 5% 5% 7% 34%	1822
September	1st to 10th	Night	19% 7% 3 6% 6% 3 4 4 5% 6% 37%	1800
	11th to 20th	Night	21% 7% 3 6% 5% 3 3 4 5% 6% 36%	1835
	21st to end	Night	23% 8% 2 5% 5% 3 5% 4 4 6% 36%	2056
October	1st to 10th	Night	22% 11% 3 7% 5% 2 5% 4 4 6% 31%	2160
	11th to 20th	Night	28% 18% 5% 8% 6% 2 4 3 3 4 19%	2160
	21st to end	Night	24% 19% 5% 8% 6% 3 3 4 4 5% 18%	2499
November	1st to 10th	Night	20% 18% 7% 8% 6% 3 5% 4 4 5% 20%	2592
	11th to 20th	Night	21% 17% 8% 12% 8% 4 4 4 4 3 15%	2660
	21st to end	Night	24% 19% 7% 12% 7% 4 4 4 4 4 11%	2660
December	1st to 10th	Night	18% 20% 8% 13% 10% 3 5% 3 4 4 11%	2660
	11th to 20th	Night	18% 19% 7% 12% 10% 4 6% 5% 3 3 13%	3526
	21st to end	Night	19% 19% 11% 15% 10% 3 4 3 3 3 11%	5236

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	76% 3 7% 11% 2	1329
	11th to 20th	Day	71% 4 7% 12% 6% 1	1295
	21st to end	Day	69% 4 5% 13% 8%	1661
February	1st to 10th	Day	68% 3 7% 15% 7%	1620
	11th to 20th	Day	67% 3 7% 16% 6%	1582
	21st to end	Day	64% 3 8% 18% 6%	1332
March	1st to 10th	Day	64% 4 6% 14% 11% 1	1910
	11th to 20th	Day	60% 3 7% 18% 11% 1	1980
	21st to end	Day	56% 3 6% 21% 11% 3	2202
April	1st to 10th	Day	64% 3 9% 14% 9% 1	2160
	11th to 20th	Day	56% 2 9% 21% 12% 1	2258
	21st to end	Day	56% 3 8% 17% 14% 2	2340
May	1st to 10th	Day	53% 4 9% 20% 12% 2	2520
	11th to 20th	Day	54% 4 8% 19% 14% 1	2482
	21st to end	Day	50% 4 11% 21% 13% 1	2765
June	1st to 10th	Day	54% 4 9% 23% 10% 1	2700
	11th to 20th	Day	48% 4 9% 24% 13% 2	2700
	21st to end	Day	51% 4 12% 22% 10% 1	2700
July	1st to 10th	Day	47% 4 14% 26% 7% 1	2626
	11th to 20th	Day	47% 5% 16% 23% 8%	2619
	21st to end	Day	52% 4 16% 23% 5%	2639
August	1st to 10th	Day	55% 4 15% 22% 3	2409
	11th to 20th	Day	51% 5% 17% 19% 8% 1	2303
	21st to end	Day	50% 4 14% 24% 8%	2516
September	1st to 10th	Day	51% 5% 14% 22% 7% 1	2160
	11th to 20th	Day	54% 4 18% 20% 5%	2124
	21st to end	Day	57% 3 12% 22% 6%	1904
October	1st to 10th	Day	56% 4 12% 19% 7% 1	1800
	11th to 20th	Day	72% 4 9% 12% 3	1800
	21st to end	Day	74% 4 7% 10% 4 1	1852
November	1st to 10th	Day	73% 3 11% 8% 4	1486
	11th to 20th	Day	78% 3 8% 9% 2	1520
	21st to end	Day	83% 3 7% 5% 2	1520
December	1st to 10th	Day	77% 3 7% 10% 2	1516
	11th to 20th	Day	74% 3 4 16% 3	1671
	21st to end	Day	82% 2 6% 8% 2	2431
January	1st to 10th	Night	77% 3 8% 10% 2	2838
	11th to 20th	Night	72% 3 8% 10% 7%	2788
	21st to end	Night	68% 3 7% 14% 8% 1	2689
February	1st to 10th	Night	65% 3 8% 15% 9%	2340
	11th to 20th	Night	66% 3 8% 15% 7%	2275
	21st to end	Night	66% 3 7% 15% 8% 1	1924
March	1st to 10th	Night	63% 3 7% 14% 10% 1	2049
	11th to 20th	Night	66% 2 6% 15% 9% 2	1980
	21st to end	Night	53% 3 8% 19% 14% 3	2153
April	1st to 10th	Night	60% 3 7% 16% 12% 2	1800
	11th to 20th	Night	52% 4 8% 22% 12% 1	1667
	21st to end	Night	54% 3 6% 18% 17% 3	1620
May	1st to 10th	Night	51% 4 9% 20% 14% 3	1440
	11th to 20th	Night	48% 5% 10% 22% 15% 1	1416
	21st to end	Night	47% 5% 11% 20% 15% 2	1507
June	1st to 10th	Night	53% 4 8% 22% 12% 2	1260
	11th to 20th	Night	44% 3 10% 25% 15% 3	1260
	21st to end	Night	44% 5% 13% 25% 13% 1	1260
July	1st to 10th	Night	44% 5% 14% 26% 11%	1225
	11th to 20th	Night	42% 4 17% 25% 11%	1218
	21st to end	Night	47% 4 18% 27% 5%	1437
August	1st to 10th	Night	48% 4 17% 27% 4	1501
	11th to 20th	Night	43% 5% 17% 27% 7% 1	1598
	21st to end	Night	50% 5% 17% 22% 7%	1822
September	1st to 10th	Night	48% 4 16% 22% 9% 1	1800
	11th to 20th	Night	50% 4 17% 23% 6%	1835
	21st to end	Night	50% 3 14% 26% 6%	2056
October	1st to 10th	Night	56% 3 13% 19% 8% 1	2160
	11th to 20th	Night	72% 3 9% 14% 2	2160
	21st to end	Night	69% 4 11% 11% 4 1	2499
November	1st to 10th	Night	68% 3 13% 13% 2	2592
	11th to 20th	Night	75% 3 8% 10% 4	2660
	21st to end	Night	79% 3 9% 8% 1	2660
December	1st to 10th	Night	79% 3 8% 8% 2	2660
	11th to 20th	Night	77% 3 6% 11% 3	3525
	21st to end	Night	81% 2 5% 8% 3	5236

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	24% 23% 36% 12% 6% 1	180
	11th to 20th	Day	22% 12% 35% 22% 6% 2	170
	21st to end	Day	17% 16% 37% 22% 7% 1	219
February	1st to 10th	Day	19% 24% 38% 15% 3 1	240
	11th to 20th	Day	23% 20% 38% 15% 4	240
	21st to end	Day	28% 21% 38% 10% 3	198
March	1st to 10th	Day	21% 16% 41% 15% 7%	415
	11th to 20th	Day	25% 17% 35% 17% 6%	420
	21st to end	Day	26% 17% 33% 15% 7% 1	462
April	1st to 10th	Day	26% 18% 27% 19% 8% 1	420
	11th to 20th	Day	24% 17% 32% 18% 7% 2	412
	21st to end	Day	30% 15% 29% 18% 6% 2	420
May	1st to 10th	Day	26% 10% 33% 22% 8% 2	423
	11th to 20th	Day	27% 16% 28% 19% 6% 3	447
	21st to end	Day	25% 14% 34% 20% 7% 1	525
June	1st to 10th	Day	27% 11% 33% 21% 7%	630
	11th to 20th	Day	22% 16% 31% 22% 7% 2	630
	21st to end	Day	22% 10% 28% 27% 11% 2	630
July	1st to 10th	Day	18% 12% 33% 27% 9% 2	621
	11th to 20th	Day	18% 11% 33% 26% 11% 1	618
	21st to end	Day	19% 8% 29% 27% 13% 3	538
August	1st to 10th	Day	21% 9% 29% 25% 11% 5%	446
	11th to 20th	Day	18% 8% 24% 27% 14% 8%	439
	21st to end	Day	25% 8% 27% 20% 13% 6%	495
September	1st to 10th	Day	24% 10% 30% 22% 11% 3	450
	11th to 20th	Day	25% 8% 32% 25% 7% 2	450
	21st to end	Day	31% 11% 25% 19% 12% 2	450
October	1st to 10th	Day	31% 10% 30% 18% 7% 3	450
	11th to 20th	Day	42% 16% 25% 14% 3 2	450
	21st to end	Day	36% 14% 29% 15% 4 1	409
November	1st to 10th	Day	36% 17% 38% 7% 2	180
	11th to 20th	Day	27% 17% 38% 16% 2 1	180
	21st to end	Day	47% 13% 30% 6% 4 1	180
December	1st to 10th	Day	28% 15% 31% 18% 8% 1	180
	11th to 20th	Day	25% 18% 38% 11% 7% 1	180
	21st to end	Day	31% 13% 36% 13% 7% 1	198
January	1st to 10th	Night	26% 12% 33% 23% 6% 1	950
	11th to 20th	Night	26% 13% 32% 22% 6%	930
	21st to end	Night	17% 11% 29% 29% 12% 1	808
February	1st to 10th	Night	19% 13% 36% 24% 7%	720
	11th to 20th	Night	21% 12% 35% 25% 6%	703
	21st to end	Night	21% 16% 35% 21% 6% 1	592
March	1st to 10th	Night	20% 18% 29% 25% 7% 1	720
	11th to 20th	Night	25% 17% 29% 23% 4 1	720
	21st to end	Night	21% 13% 35% 25% 6% 1	792
April	1st to 10th	Night	29% 12% 30% 22% 8% 1	720
	11th to 20th	Night	22% 16% 27% 25% 9% 1	603
	21st to end	Night	24% 8% 31% 29% 7% 1	540
May	1st to 10th	Night	23% 6% 34% 26% 10% 1	360
	11th to 20th	Night	25% 9% 28% 29% 8% 2	354
	21st to end	Night	22% 10% 30% 32% 7%	389
June	1st to 10th	Night	25% 6% 33% 28% 8% 1	360
	11th to 20th	Night	21% 9% 28% 33% 9%	360
	21st to end	Night	17% 10% 24% 36% 13%	360
July	1st to 10th	Night	20% 6% 29% 33% 11% 1	350
	11th to 20th	Night	19% 4 25% 40% 11% 1	348
	21st to end	Night	15% 6% 24% 41% 12% 2	394
August	1st to 10th	Night	21% 5% 24% 31% 17% 2	437
	11th to 20th	Night	18% 4 25% 29% 21% 2	534
	21st to end	Night	24% 8% 22% 28% 15% 2	634
September	1st to 10th	Night	23% 8% 27% 28% 13% 2	720
	11th to 20th	Night	26% 9% 27% 25% 12% 1	720
	21st to end	Night	27% 8% 23% 29% 13% 1	720
October	1st to 10th	Night	28% 12% 25% 26% 9% 1	720
	11th to 20th	Night	37% 12% 27% 15% 7% 1	720
	21st to end	Night	37% 10% 27% 20% 5% 1	792
November	1st to 10th	Night	31% 11% 34% 18% 6% 1	740
	11th to 20th	Night	31% 15% 31% 18% 6%	760
	21st to end	Night	33% 16% 31% 15% 4 1	760
December	1st to 10th	Night	29% 14% 29% 20% 7% 1	760
	11th to 20th	Night	29% 12% 32% 19% 7% 1	950
	21st to end	Night	28% 16% 26% 21% 8% 2	1045

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