Saint-Hugues
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Saint-Hugues clear sky chart from 2005-11-06 to 2026-03-03.

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	17% 10% 3 8% 5% 5% 4 4 5% 7% 31%	131010
	Night	18% 12% 4 10% 5% 5% 4 3 5% 6% 29%	130168
Transparency	Day	51% 7% 13% 20% 8% 1	134453
	Night	56% 6% 11% 17% 9% 1	134799
Seeing	Day	23% 14% 29% 22% 10% 2	16155
	Night	24% 11% 30% 26% 9% 1	25200

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	17% 19% 7% 13% 5% 4 4 3 3 4 23%	4661
	11th to 20th	Day	13% 16% 6% 14% 7% 6% 5% 3 4 4 21%	4650
	21st to end	Day	10% 13% 5% 12% 8% 8% 6% 4 6% 5% 24%	5124
February	1st to 10th	Day	15% 15% 5% 10% 6% 5% 5% 4 4 4 26%	1785
	11th to 20th	Day	15% 15% 5% 10% 6% 5% 4 3 5% 5% 26%	1991
	21st to end	Day	17% 14% 4 8% 6% 5% 4 4 5% 5% 27%	1730
March	1st to 10th	Day	19% 13% 4 10% 7% 5% 4 3 4 5% 25%	4496
	11th to 20th	Day	13% 12% 4 8% 5% 4 5% 4 5% 7% 33%	4651
	21st to end	Day	19% 12% 4 9% 4 4 4 3 4 5% 32%	5970
April	1st to 10th	Day	22% 11% 4 8% 5% 5% 4 3 4 6% 30%	2400
	11th to 20th	Day	21% 9% 2 6% 4 4 5% 3 5% 5% 36%	2383
	21st to end	Day	23% 10% 3 6% 4 4 4 3 5% 6% 31%	2600
May	1st to 10th	Day	27% 10% 3 8% 5% 4 4 4 4 6% 24%	6157
	11th to 20th	Day	19% 8% 3 9% 5% 5% 5% 4 6% 7% 30%	6318
	21st to end	Day	19% 9% 3 7% 4 4 4 4 5% 7% 32%	6949
June	1st to 10th	Day	21% 8% 2 7% 5% 4 4 5% 5% 8% 31%	2800
	11th to 20th	Day	15% 6% 3 5% 5% 5% 4 4 7% 8% 38%	2800
	21st to end	Day	21% 8% 3 7% 4 4 4 4 6% 8% 30%	2800
July	1st to 10th	Day	14% 7% 3 7% 6% 6% 6% 5% 7% 9% 31%	6360
	11th to 20th	Day	12% 6% 3 6% 4 5% 5% 5% 7% 9% 39%	6360
	21st to end	Day	11% 6% 2 5% 4 4 5% 4 6% 10% 45%	6926
August	1st to 10th	Day	14% 6% 3 7% 5% 6% 6% 4 8% 9% 32%	4563
	11th to 20th	Day	16% 7% 3 6% 4 5% 5% 4 7% 9% 35%	4165
	21st to end	Day	17% 6% 2 6% 4 4 4 3 5% 7% 39%	4312
September	1st to 10th	Day	12% 5% 2 7% 4 4 5% 4 7% 9% 42%	2400
	11th to 20th	Day	15% 6% 1 5% 3 2 3 3 5% 8% 48%	2280
	21st to end	Day	18% 6% 2 6% 4 4 4 3 6% 8% 40%	2200
October	1st to 10th	Day	20% 6% 2 7% 4 5% 4 3 6% 7% 36%	2115
	11th to 20th	Day	18% 9% 3 8% 5% 6% 4 5% 5% 6% 30%	1911
	21st to end	Day	25% 10% 3 7% 4 4 4 3 4 6% 29%	1980
November	1st to 10th	Day	18% 12% 3 7% 6% 3 5% 4 5% 6% 31%	1851
	11th to 20th	Day	18% 13% 4 8% 5% 4 4 3 5% 6% 29%	1848
	21st to end	Day	24% 14% 4 7% 5% 4 4 3 5% 6% 25%	1680
December	1st to 10th	Day	20% 18% 5% 12% 7% 4 4 3 4 5% 18%	2680
	11th to 20th	Day	19% 13% 5% 11% 6% 4 3 3 4 5% 27%	3066
	21st to end	Day	23% 13% 4 10% 5% 5% 5% 5% 5% 5% 18%	4048
January	1st to 10th	Night	14% 20% 7% 13% 5% 4 4 3 4 4 21%	8234
	11th to 20th	Night	13% 18% 7% 17% 8% 6% 5% 3 4 4 16%	8235
	21st to end	Night	10% 14% 5% 14% 9% 6% 4 4 5% 5% 24%	9057
February	1st to 10th	Night	14% 15% 5% 13% 7% 5% 4 3 5% 5% 23%	2831
	11th to 20th	Night	14% 14% 5% 12% 7% 5% 5% 3 4 4 27%	2515
	21st to end	Night	15% 15% 5% 9% 6% 4 3 4 5% 5% 30%	2076
March	1st to 10th	Night	21% 13% 4 9% 6% 4 3 3 4 4 28%	5389
	11th to 20th	Night	16% 14% 4 8% 5% 5% 4 3 5% 7% 29%	5292
	21st to end	Night	16% 13% 5% 11% 5% 4 4 3 4 5% 30%	4962
April	1st to 10th	Night	24% 10% 4 7% 4 4 4 2 4 7% 30%	2000
	11th to 20th	Night	22% 7% 3 7% 5% 3 5% 3 5% 6% 32%	1965
	21st to end	Night	24% 9% 3 6% 4 3 3 3 5% 6% 34%	1800
May	1st to 10th	Night	27% 10% 4 9% 5% 4 4 3 4 6% 24%	3827
	11th to 20th	Night	24% 7% 2 8% 5% 5% 4 3 5% 6% 31%	3575
	21st to end	Night	18% 9% 3 9% 5% 4 4 4 6% 8% 30%	3926
June	1st to 10th	Night	23% 7% 3 6% 3 4 6% 4 5% 7% 33%	1600
	11th to 20th	Night	18% 5% 3 6% 5% 4 5% 5% 7% 8% 36%	1600
	21st to end	Night	19% 7% 3 7% 5% 4 4 5% 6% 8% 33%	1600
July	1st to 10th	Night	13% 7% 3 7% 6% 6% 6% 5% 8% 9% 31%	3600
	11th to 20th	Night	15% 6% 2 6% 4 5% 5% 4 6% 8% 38%	3600
	21st to end	Night	10% 5% 2 7% 5% 5% 6% 5% 6% 8% 41%	3926
August	1st to 10th	Night	17% 8% 3 8% 4 4 4 4 5% 7% 35%	2586
	11th to 20th	Night	16% 6% 2 7% 5% 5% 5% 4 5% 7% 37%	2845
	21st to end	Night	18% 5% 2 7% 4 5% 4 3 5% 7% 39%	3586
September	1st to 10th	Night	14% 6% 2 6% 4 4 5% 3 6% 7% 45%	2000
	11th to 20th	Night	15% 4 2 5% 4 3 4 2 4 6% 50%	2119
	21st to end	Night	17% 7% 2 6% 4 4 4 3 4 6% 42%	2200
October	1st to 10th	Night	18% 6% 2 6% 4 3 4 3 5% 6% 41%	2280
	11th to 20th	Night	21% 9% 2 7% 4 5% 4 3 4 6% 35%	2487
	21st to end	Night	24% 9% 3 8% 5% 5% 4 3 4 5% 30%	2860
November	1st to 10th	Night	20% 11% 4 7% 4 4 4 3 5% 5% 31%	2667
	11th to 20th	Night	19% 12% 3 8% 5% 4 4 3 4 5% 31%	2770
	21st to end	Night	22% 16% 4 8% 4 4 3 3 4 5% 26%	2940
December	1st to 10th	Night	19% 19% 6% 13% 7% 6% 4 3 4 4 16%	4720
	11th to 20th	Night	23% 13% 5% 10% 5% 4 4 3 4 5% 26%	5348
	21st to end	Night	23% 17% 4 9% 4 4 4 4 6% 6% 21%	7150

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	67% 7% 9% 15% 3	4662
	11th to 20th	Day	66% 6% 8% 12% 7%	4680
	21st to end	Day	61% 6% 9% 13% 10%	5124
February	1st to 10th	Day	62% 6% 8% 17% 6% 1	1785
	11th to 20th	Day	60% 6% 12% 14% 7% 1	2000
	21st to end	Day	59% 6% 11% 16% 7% 2	1730
March	1st to 10th	Day	62% 7% 8% 13% 9% 3	4499
	11th to 20th	Day	50% 9% 16% 13% 11% 1	4651
	21st to end	Day	54% 5% 9% 17% 13% 1	5970
April	1st to 10th	Day	57% 5% 10% 17% 10% 1	2400
	11th to 20th	Day	49% 6% 10% 21% 13% 1	2383
	21st to end	Day	54% 6% 11% 17% 11% 2	2600
May	1st to 10th	Day	60% 7% 9% 18% 6% 1	6168
	11th to 20th	Day	49% 10% 15% 16% 8% 1	6322
	21st to end	Day	49% 8% 12% 19% 11% 1	6949
June	1st to 10th	Day	51% 7% 11% 20% 9% 2	2800
	11th to 20th	Day	42% 8% 14% 22% 12% 2	2800
	21st to end	Day	51% 8% 11% 20% 9% 1	2800
July	1st to 10th	Day	46% 8% 15% 24% 6%	6290
	11th to 20th	Day	39% 8% 16% 29% 8%	6285
	21st to end	Day	35% 7% 16% 34% 7%	6728
August	1st to 10th	Day	46% 8% 18% 21% 6%	4549
	11th to 20th	Day	43% 9% 20% 21% 6%	4205
	21st to end	Day	45% 6% 15% 20% 13%	4312
September	1st to 10th	Day	36% 9% 16% 28% 9% 1	2400
	11th to 20th	Day	35% 6% 14% 32% 12%	2280
	21st to end	Day	42% 7% 14% 25% 11%	2200
October	1st to 10th	Day	43% 6% 16% 28% 7%	3440
	11th to 20th	Day	45% 7% 18% 24% 5%	3088
	21st to end	Day	46% 6% 20% 20% 7%	3180
November	1st to 10th	Day	53% 7% 14% 19% 7%	1851
	11th to 20th	Day	55% 8% 13% 16% 8%	1848
	21st to end	Day	62% 8% 14% 12% 4	1680
December	1st to 10th	Day	71% 5% 8% 13% 3	2680
	11th to 20th	Day	62% 5% 9% 17% 8%	3066
	21st to end	Day	65% 8% 11% 10% 6%	4048
January	1st to 10th	Night	66% 6% 11% 12% 4 1	8234
	11th to 20th	Night	70% 8% 9% 9% 4	8280
	21st to end	Night	62% 5% 9% 12% 12%	9057
February	1st to 10th	Night	63% 6% 8% 15% 7% 1	2831
	11th to 20th	Night	60% 6% 9% 16% 8%	2517
	21st to end	Night	56% 6% 9% 16% 11% 1	2076
March	1st to 10th	Night	59% 5% 8% 14% 11% 4	5399
	11th to 20th	Night	53% 7% 13% 14% 11% 1	5293
	21st to end	Night	56% 6% 7% 20% 10% 2	4962
April	1st to 10th	Night	55% 5% 9% 17% 12% 1	2000
	11th to 20th	Night	52% 6% 8% 18% 14% 2	1965
	21st to end	Night	51% 6% 9% 18% 14% 2	1800
May	1st to 10th	Night	60% 8% 9% 15% 7% 2	3833
	11th to 20th	Night	51% 8% 12% 18% 9% 1	3576
	21st to end	Night	51% 7% 11% 17% 13% 1	3927
June	1st to 10th	Night	49% 8% 11% 20% 11% 1	1600
	11th to 20th	Night	45% 7% 11% 20% 14% 3	1600
	21st to end	Night	47% 10% 11% 19% 13% 1	1600
July	1st to 10th	Night	46% 8% 18% 19% 8%	3560
	11th to 20th	Night	42% 7% 17% 25% 9%	3552
	21st to end	Night	38% 8% 17% 26% 11%	3809
August	1st to 10th	Night	47% 8% 13% 25% 7%	2576
	11th to 20th	Night	46% 8% 17% 22% 7%	2871
	21st to end	Night	43% 7% 12% 23% 14% 1	3586
September	1st to 10th	Night	39% 8% 13% 26% 14% 1	2000
	11th to 20th	Night	35% 6% 16% 32% 12% 1	2119
	21st to end	Night	42% 7% 10% 26% 14%	2200
October	1st to 10th	Night	47% 6% 13% 23% 10%	3722
	11th to 20th	Night	46% 5% 11% 30% 7%	4049
	21st to end	Night	50% 5% 14% 18% 11% 2	4610
November	1st to 10th	Night	54% 6% 12% 20% 6% 1	2667
	11th to 20th	Night	56% 6% 12% 16% 9% 1	2770
	21st to end	Night	61% 6% 12% 15% 6%	2940
December	1st to 10th	Night	73% 4 11% 9% 3	4720
	11th to 20th	Night	63% 6% 9% 14% 9%	5348
	21st to end	Night	63% 5% 9% 14% 8%	7150

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	30% 16% 30% 19% 4	220
	11th to 20th	Day	31% 20% 30% 15% 3	220
	21st to end	Day	19% 21% 31% 20% 7% 1	242
February	1st to 10th	Day	28% 20% 31% 16% 4 1	275
	11th to 20th	Day	25% 17% 35% 19% 3	479
	21st to end	Day	24% 18% 33% 23% 2	446
March	1st to 10th	Day	25% 16% 31% 24% 5%	508
	11th to 20th	Day	22% 20% 33% 21% 4 1	500
	21st to end	Day	27% 18% 28% 20% 6% 1	550
April	1st to 10th	Day	30% 15% 27% 21% 6% 2	500
	11th to 20th	Day	28% 21% 24% 18% 7% 2	492
	21st to end	Day	27% 16% 36% 11% 7% 2	500
May	1st to 10th	Day	27% 14% 31% 18% 9% 1	503
	11th to 20th	Day	17% 14% 31% 23% 13% 2	527
	21st to end	Day	21% 18% 31% 20% 9% 2	573
June	1st to 10th	Day	22% 16% 30% 22% 7% 2	530
	11th to 20th	Day	16% 14% 30% 25% 13% 1	530
	21st to end	Day	26% 10% 29% 23% 10% 2	530
July	1st to 10th	Day	14% 9% 31% 27% 17% 2	525
	11th to 20th	Day	15% 9% 31% 32% 11% 2	524
	21st to end	Day	17% 7% 30% 31% 14% 2	576
August	1st to 10th	Day	17% 5% 26% 29% 18% 5%	526
	11th to 20th	Day	15% 6% 24% 31% 19% 5%	519
	21st to end	Day	18% 10% 25% 22% 17% 9%	583
September	1st to 10th	Day	14% 10% 29% 28% 13% 7%	530
	11th to 20th	Day	15% 8% 23% 25% 19% 10%	530
	21st to end	Day	19% 12% 24% 25% 15% 6%	530
October	1st to 10th	Day	19% 12% 29% 23% 13% 4	530
	11th to 20th	Day	23% 18% 24% 23% 10% 2	480
	21st to end	Day	34% 12% 28% 20% 6%	462
November	1st to 10th	Day	29% 18% 28% 20% 5%	425
	11th to 20th	Day	29% 18% 27% 18% 8% 1	388
	21st to end	Day	33% 19% 29% 15% 5%	220
December	1st to 10th	Day	31% 12% 28% 20% 5% 2	220
	11th to 20th	Day	26% 24% 32% 15% 2 1	220
	21st to end	Day	30% 21% 27% 16% 5% 2	242
January	1st to 10th	Night	28% 13% 31% 23% 5%	840
	11th to 20th	Night	27% 15% 31% 20% 7%	840
	21st to end	Night	21% 12% 34% 28% 6%	924
February	1st to 10th	Night	23% 12% 36% 23% 6%	840
	11th to 20th	Night	21% 14% 39% 22% 4 1	823
	21st to end	Night	23% 14% 34% 24% 4	692
March	1st to 10th	Night	25% 14% 33% 24% 4	809
	11th to 20th	Night	27% 12% 32% 23% 6%	800
	21st to end	Night	24% 12% 32% 25% 7%	880
April	1st to 10th	Night	29% 13% 27% 26% 5%	800
	11th to 20th	Night	25% 14% 30% 24% 5% 1	781
	21st to end	Night	28% 15% 29% 21% 8% 1	600
May	1st to 10th	Night	27% 10% 33% 24% 6% 1	503
	11th to 20th	Night	23% 9% 28% 32% 8% 1	394
	21st to end	Night	20% 9% 37% 27% 7%	433
June	1st to 10th	Night	25% 9% 29% 29% 8% 1	400
	11th to 20th	Night	19% 6% 30% 35% 10%	400
	21st to end	Night	19% 7% 29% 34% 12% 1	400
July	1st to 10th	Night	13% 6% 29% 40% 12% 1	390
	11th to 20th	Night	12% 4 27% 42% 14% 1	388
	21st to end	Night	12% 5% 27% 44% 11% 1	438
August	1st to 10th	Night	16% 4 18% 40% 20% 2	398
	11th to 20th	Night	15% 3 23% 35% 22% 2	563
	21st to end	Night	17% 5% 25% 33% 18% 2	880
September	1st to 10th	Night	17% 7% 25% 35% 15% 2	800
	11th to 20th	Night	18% 5% 20% 33% 21% 3	800
	21st to end	Night	20% 6% 29% 28% 15% 2	800
October	1st to 10th	Night	21% 8% 30% 28% 13% 1	800
	11th to 20th	Night	25% 10% 29% 27% 9% 1	800
	21st to end	Night	30% 11% 31% 23% 4	880
November	1st to 10th	Night	27% 14% 32% 21% 6%	820
	11th to 20th	Night	25% 14% 32% 20% 8% 1	840
	21st to end	Night	31% 15% 27% 21% 5%	840
December	1st to 10th	Night	32% 14% 28% 20% 6%	840
	11th to 20th	Night	29% 15% 30% 19% 5% 1	840
	21st to end	Night	35% 12% 28% 19% 5%	924

Page generated at 2026-02-28 01:40:24. Version ac07

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