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 2024-12-02.

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	18% 10% 3 7% 5% 4 4 4 5% 7% 32%	101742
	Night	19% 11% 4 8% 5% 4 4 3 5% 6% 31%	97897
Transparency	Day	50% 8% 14% 20% 8% 1	105203
	Night	53% 7% 12% 18% 9% 1	102512
Seeing	Day	23% 14% 29% 23% 10% 3	14670
	Night	24% 11% 30% 26% 9% 1	23600

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	19% 17% 7% 12% 5% 4 3 3 3 3 24%	2517
	11th to 20th	Day	16% 14% 5% 10% 5% 4 4 3 5% 5% 29%	2520
	21st to end	Day	13% 16% 5% 11% 6% 5% 5% 4 5% 5% 24%	2772
February	1st to 10th	Day	17% 15% 5% 10% 6% 4 5% 4 4 4 25%	1615
	11th to 20th	Day	15% 15% 5% 10% 7% 5% 4 3 5% 5% 26%	1796
	21st to end	Day	18% 14% 4 8% 6% 5% 3 4 5% 5% 27%	1570
March	1st to 10th	Day	20% 11% 4 9% 7% 6% 4 3 4 5% 28%	3116
	11th to 20th	Day	16% 16% 5% 10% 5% 4 4 3 4 5% 27%	3249
	21st to end	Day	15% 11% 4 8% 4 4 3 4 4 6% 37%	4166
April	1st to 10th	Day	22% 11% 4 8% 5% 5% 4 3 4 6% 29%	2280
	11th to 20th	Day	21% 9% 2 6% 4 4 5% 3 5% 5% 36%	2262
	21st to end	Day	23% 10% 3 6% 4 4 4 3 4 6% 32%	2470
May	1st to 10th	Day	22% 9% 3 7% 4 4 4 4 4 7% 31%	4293
	11th to 20th	Day	17% 7% 3 9% 6% 5% 5% 5% 6% 8% 30%	4398
	21st to end	Day	15% 7% 2 6% 4 5% 5% 5% 6% 9% 36%	4837
June	1st to 10th	Day	21% 8% 2 7% 5% 4 4 5% 5% 8% 30%	2660
	11th to 20th	Day	15% 6% 3 5% 5% 5% 4 4 7% 8% 38%	2660
	21st to end	Day	21% 8% 3 7% 4 4 4 4 6% 7% 30%	2660
July	1st to 10th	Day	13% 6% 2 6% 5% 6% 5% 5% 7% 9% 35%	4440
	11th to 20th	Day	14% 6% 3 6% 5% 5% 5% 5% 7% 9% 36%	4440
	21st to end	Day	12% 6% 2 5% 4 4 5% 4 6% 8% 44%	4814
August	1st to 10th	Day	15% 7% 3 7% 5% 6% 6% 4 8% 9% 31%	4423
	11th to 20th	Day	16% 7% 3 6% 4 5% 5% 4 7% 9% 35%	4035
	21st to end	Day	18% 6% 2 6% 4 4 4 3 6% 7% 39%	4180
September	1st to 10th	Day	12% 6% 2 7% 4 4 5% 4 7% 8% 41%	2280
	11th to 20th	Day	16% 6% 1 5% 3 2 3 3 5% 8% 47%	2166
	21st to end	Day	18% 6% 2 5% 4 4 4 3 6% 8% 40%	2090
October	1st to 10th	Day	21% 6% 2 7% 4 5% 4 3 6% 7% 33%	2009
	11th to 20th	Day	19% 9% 3 8% 5% 6% 4 5% 6% 6% 29%	1816
	21st to end	Day	25% 10% 3 7% 4 4 4 3 4 6% 30%	1881
November	1st to 10th	Day	17% 11% 3 7% 6% 3 5% 4 5% 6% 32%	1761
	11th to 20th	Day	18% 13% 4 8% 4 4 4 3 5% 6% 30%	1760
	21st to end	Day	23% 14% 4 7% 5% 4 4 3 5% 6% 25%	1600
December	1st to 10th	Day	25% 17% 5% 9% 6% 4 5% 3 4 4 19%	1528
	11th to 20th	Day	22% 15% 5% 8% 5% 4 3 2 4 5% 27%	1906
	21st to end	Day	27% 16% 5% 10% 5% 4 4 2 3 4 21%	2772
January	1st to 10th	Night	17% 18% 5% 11% 5% 4 4 3 4 5% 23%	4429
	11th to 20th	Night	13% 15% 4 14% 8% 6% 5% 4 5% 5% 22%	4440
	21st to end	Night	16% 17% 6% 12% 7% 5% 4 3 4 4 23%	4884
February	1st to 10th	Night	15% 16% 5% 12% 8% 5% 4 3 5% 5% 22%	2562
	11th to 20th	Night	14% 14% 5% 11% 7% 5% 5% 3 4 4 27%	2270
	21st to end	Night	16% 15% 5% 8% 6% 4 3 3 5% 5% 30%	1884
March	1st to 10th	Night	22% 11% 4 8% 5% 4 3 3 4 4 32%	3724
	11th to 20th	Night	19% 18% 5% 9% 4 4 4 2 4 4 27%	3694
	21st to end	Night	14% 12% 5% 10% 5% 4 4 3 4 5% 35%	3466
April	1st to 10th	Night	24% 10% 4 7% 4 4 4 2 4 7% 29%	1900
	11th to 20th	Night	23% 7% 3 7% 5% 3 5% 3 5% 6% 33%	1866
	21st to end	Night	24% 9% 3 6% 4 3 3 3 5% 6% 34%	1710
May	1st to 10th	Night	24% 10% 3 8% 5% 4 4 3 5% 6% 28%	2677
	11th to 20th	Night	22% 6% 2 7% 5% 4 4 3 5% 6% 34%	2495
	21st to end	Night	17% 6% 3 7% 4 4 4 4 6% 9% 36%	2738
June	1st to 10th	Night	22% 8% 3 5% 3 4 6% 4 5% 7% 33%	1520
	11th to 20th	Night	18% 5% 3 6% 4 4 4 5% 6% 8% 37%	1520
	21st to end	Night	20% 7% 3 7% 5% 4 5% 5% 6% 7% 33%	1520
July	1st to 10th	Night	13% 8% 3 7% 6% 5% 5% 4 7% 8% 33%	2520
	11th to 20th	Night	15% 6% 2 6% 5% 5% 5% 4 6% 8% 39%	2520
	21st to end	Night	12% 5% 2 7% 5% 5% 5% 4 5% 8% 41%	2739
August	1st to 10th	Night	18% 8% 3 8% 5% 5% 4 4 5% 7% 34%	2506
	11th to 20th	Night	17% 7% 3 7% 5% 5% 5% 4 5% 7% 36%	2756
	21st to end	Night	18% 5% 2 7% 4 5% 4 3 5% 7% 39%	3476
September	1st to 10th	Night	14% 6% 2 6% 4 4 5% 3 6% 6% 44%	1900
	11th to 20th	Night	16% 5% 2 5% 4 2 4 2 4 7% 49%	2013
	21st to end	Night	17% 7% 2 6% 4 4 4 3 4 6% 42%	2090
October	1st to 10th	Night	19% 7% 2 6% 5% 4 4 3 5% 6% 40%	2166
	11th to 20th	Night	22% 9% 2 8% 4 5% 4 2 4 6% 34%	2362
	21st to end	Night	24% 9% 3 8% 5% 5% 4 3 4 5% 30%	2717
November	1st to 10th	Night	19% 12% 4 7% 5% 4 4 3 5% 5% 31%	2537
	11th to 20th	Night	19% 12% 3 8% 5% 4 4 3 4 5% 32%	2638
	21st to end	Night	23% 15% 4 8% 4 4 3 3 4 5% 26%	2800
December	1st to 10th	Night	23% 18% 5% 10% 6% 4 4 3 4 5% 19%	2686
	11th to 20th	Night	23% 15% 5% 9% 5% 3 3 3 4 4 25%	3288
	21st to end	Night	26% 18% 4 9% 4 4 3 2 3 4 23%	4884

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	65% 9% 11% 12% 2	2518
	11th to 20th	Day	57% 10% 11% 17% 5%	2520
	21st to end	Day	60% 9% 13% 13% 4	2772
February	1st to 10th	Day	63% 6% 8% 16% 5% 1	1615
	11th to 20th	Day	61% 7% 12% 12% 7% 1	1805
	21st to end	Day	58% 6% 11% 15% 7% 2	1570
March	1st to 10th	Day	58% 9% 9% 16% 7% 1	3119
	11th to 20th	Day	57% 9% 13% 9% 10% 1	3249
	21st to end	Day	48% 6% 10% 20% 14% 2	4166
April	1st to 10th	Day	57% 5% 10% 16% 9% 2	2280
	11th to 20th	Day	49% 7% 10% 21% 12% 1	2262
	21st to end	Day	54% 6% 11% 16% 10% 3	2470
May	1st to 10th	Day	51% 8% 12% 20% 8% 1	4307
	11th to 20th	Day	46% 12% 17% 15% 8% 1	4402
	21st to end	Day	42% 10% 13% 22% 12% 1	4837
June	1st to 10th	Day	51% 8% 12% 20% 9% 2	2660
	11th to 20th	Day	42% 8% 15% 21% 12% 2	2660
	21st to end	Day	52% 9% 11% 19% 9%	2660
July	1st to 10th	Day	42% 9% 15% 26% 8%	4370
	11th to 20th	Day	43% 8% 17% 27% 5%	4365
	21st to end	Day	37% 8% 16% 31% 7%	4661
August	1st to 10th	Day	47% 8% 18% 21% 6%	4409
	11th to 20th	Day	44% 9% 21% 21% 6%	4075
	21st to end	Day	44% 6% 16% 20% 14%	4180
September	1st to 10th	Day	38% 9% 16% 26% 10% 1	2280
	11th to 20th	Day	36% 6% 14% 31% 12%	2166
	21st to end	Day	42% 8% 15% 25% 10%	2090
October	1st to 10th	Day	45% 6% 16% 28% 6%	3334
	11th to 20th	Day	46% 7% 19% 23% 5%	2993
	21st to end	Day	45% 6% 20% 20% 7%	3081
November	1st to 10th	Day	51% 7% 14% 20% 7% 1	1761
	11th to 20th	Day	54% 8% 13% 16% 9%	1760
	21st to end	Day	61% 8% 14% 13% 4	1600
December	1st to 10th	Day	70% 6% 11% 10% 3	1528
	11th to 20th	Day	62% 6% 10% 17% 6%	1906
	21st to end	Day	67% 8% 11% 9% 5%	2772
January	1st to 10th	Night	62% 10% 14% 10% 4	4429
	11th to 20th	Night	61% 12% 12% 11% 4	4440
	21st to end	Night	65% 6% 11% 12% 6%	4884
February	1st to 10th	Night	65% 6% 8% 14% 6% 1	2562
	11th to 20th	Night	60% 6% 9% 16% 8%	2272
	21st to end	Night	56% 6% 10% 15% 12% 1	1884
March	1st to 10th	Night	55% 6% 11% 17% 8% 3	3734
	11th to 20th	Night	59% 8% 9% 12% 11% 2	3695
	21st to end	Night	51% 8% 8% 20% 12% 2	3466
April	1st to 10th	Night	55% 6% 10% 16% 12% 1	1900
	11th to 20th	Night	51% 6% 8% 19% 13% 2	1866
	21st to end	Night	51% 6% 9% 18% 14% 2	1710
May	1st to 10th	Night	54% 9% 11% 16% 8% 2	2683
	11th to 20th	Night	47% 10% 14% 19% 9% 2	2496
	21st to end	Night	44% 7% 12% 19% 16% 1	2739
June	1st to 10th	Night	49% 8% 11% 20% 10% 1	1520
	11th to 20th	Night	44% 7% 12% 20% 13% 3	1520
	21st to end	Night	48% 10% 11% 18% 12% 1	1520
July	1st to 10th	Night	45% 8% 16% 19% 11%	2480
	11th to 20th	Night	41% 8% 18% 25% 9%	2472
	21st to end	Night	39% 9% 18% 22% 12%	2651
August	1st to 10th	Night	49% 8% 13% 24% 6%	2496
	11th to 20th	Night	47% 8% 17% 22% 6%	2782
	21st to end	Night	44% 7% 12% 22% 14% 1	3476
September	1st to 10th	Night	39% 8% 14% 24% 14% 1	1900
	11th to 20th	Night	35% 6% 16% 31% 11% 1	2013
	21st to end	Night	42% 7% 11% 26% 14%	2090
October	1st to 10th	Night	48% 6% 13% 23% 10%	3608
	11th to 20th	Night	47% 5% 11% 30% 7%	3924
	21st to end	Night	50% 5% 15% 18% 11% 2	4467
November	1st to 10th	Night	54% 7% 12% 19% 7% 1	2537
	11th to 20th	Night	55% 6% 12% 16% 9% 2	2638
	21st to end	Night	61% 6% 12% 15% 6%	2800
December	1st to 10th	Night	70% 5% 11% 11% 3	2686
	11th to 20th	Night	63% 6% 10% 15% 6%	3288
	21st to end	Night	67% 6% 9% 14% 4	4884

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% 31% 19% 4 1	180
	11th to 20th	Day	31% 19% 30% 16% 4	180
	21st to end	Day	20% 20% 30% 21% 8% 1	198
February	1st to 10th	Day	33% 21% 28% 15% 2 1	225
	11th to 20th	Day	25% 17% 36% 18% 3	404
	21st to end	Day	25% 19% 30% 23% 2	382
March	1st to 10th	Day	25% 14% 30% 25% 5%	460
	11th to 20th	Day	22% 20% 32% 20% 5% 1	460
	21st to end	Day	26% 17% 28% 21% 7% 1	506
April	1st to 10th	Day	30% 13% 28% 20% 7% 2	460
	11th to 20th	Day	28% 20% 25% 17% 7% 2	452
	21st to end	Day	27% 17% 36% 12% 7% 2	460
May	1st to 10th	Day	26% 15% 31% 18% 10% 1	463
	11th to 20th	Day	17% 14% 32% 23% 13% 2	487
	21st to end	Day	19% 18% 32% 21% 9% 2	529
June	1st to 10th	Day	22% 16% 29% 22% 8% 2	490
	11th to 20th	Day	17% 13% 31% 24% 13% 1	490
	21st to end	Day	27% 10% 28% 23% 10% 2	490
July	1st to 10th	Day	13% 8% 31% 28% 17% 3	485
	11th to 20th	Day	16% 8% 30% 33% 11% 2	484
	21st to end	Day	18% 7% 28% 32% 14% 2	532
August	1st to 10th	Day	18% 6% 27% 27% 18% 5%	486
	11th to 20th	Day	16% 6% 25% 30% 18% 5%	479
	21st to end	Day	18% 10% 24% 23% 16% 9%	539
September	1st to 10th	Day	15% 10% 29% 28% 11% 7%	490
	11th to 20th	Day	16% 8% 23% 25% 18% 10%	490
	21st to end	Day	19% 10% 24% 25% 16% 6%	490
October	1st to 10th	Day	20% 12% 29% 22% 13% 4	490
	11th to 20th	Day	24% 18% 24% 22% 9% 2	445
	21st to end	Day	33% 13% 28% 20% 6%	429
November	1st to 10th	Day	28% 17% 28% 22% 5%	395
	11th to 20th	Day	28% 19% 26% 18% 8% 1	360
	21st to end	Day	32% 18% 29% 17% 5%	200
December	1st to 10th	Day	34% 12% 25% 20% 5% 3	182
	11th to 20th	Day	27% 23% 32% 16% 2 1	180
	21st to end	Day	32% 23% 26% 14% 5% 1	198
January	1st to 10th	Night	28% 14% 29% 23% 6%	760
	11th to 20th	Night	26% 15% 32% 21% 7%	760
	21st to end	Night	21% 11% 33% 28% 6%	836
February	1st to 10th	Night	24% 12% 37% 21% 5%	760
	11th to 20th	Night	20% 15% 39% 22% 4 1	743
	21st to end	Night	24% 13% 34% 24% 4	628
March	1st to 10th	Night	25% 13% 33% 25% 4	760
	11th to 20th	Night	28% 12% 31% 23% 6%	760
	21st to end	Night	24% 11% 32% 25% 7%	836
April	1st to 10th	Night	29% 13% 26% 27% 5%	760
	11th to 20th	Night	25% 14% 30% 25% 6% 1	742
	21st to end	Night	28% 15% 28% 21% 8% 1	570
May	1st to 10th	Night	26% 10% 33% 24% 6% 1	478
	11th to 20th	Night	23% 9% 28% 32% 8% 1	374
	21st to end	Night	20% 9% 38% 26% 7%	411
June	1st to 10th	Night	25% 9% 29% 28% 8% 1	380
	11th to 20th	Night	20% 5% 29% 35% 11%	380
	21st to end	Night	19% 7% 28% 34% 12% 1	380
July	1st to 10th	Night	13% 6% 29% 39% 12% 1	370
	11th to 20th	Night	12% 3 27% 42% 14% 1	368
	21st to end	Night	13% 5% 26% 44% 11% 1	416
August	1st to 10th	Night	17% 4 17% 40% 20% 2	378
	11th to 20th	Night	16% 3 23% 34% 22% 2	534
	21st to end	Night	17% 5% 25% 33% 18% 2	836
September	1st to 10th	Night	17% 7% 25% 35% 14% 2	760
	11th to 20th	Night	19% 6% 20% 32% 21% 3	760
	21st to end	Night	20% 6% 28% 28% 15% 2	760
October	1st to 10th	Night	21% 9% 30% 27% 12% 1	760
	11th to 20th	Night	26% 10% 28% 26% 9% 1	760
	21st to end	Night	30% 11% 31% 23% 4	836
November	1st to 10th	Night	26% 14% 32% 21% 6%	780
	11th to 20th	Night	25% 15% 32% 20% 8% 1	800
	21st to end	Night	31% 15% 27% 21% 6% 1	800
December	1st to 10th	Night	33% 14% 27% 20% 6%	768
	11th to 20th	Night	28% 14% 30% 20% 5% 1	760
	21st to end	Night	35% 13% 28% 19% 5%	836

Page generated at 2024-11-29 10:43:07. Version ac07

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