Tour d'observation Montagnes Noires
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Tour d'observation Montagnes Noires 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	17% 10% 3 8% 5% 5% 4 4 5% 7% 31%	101776
	Night	17% 12% 4 8% 5% 4 4 3 5% 6% 32%	97849
Transparency	Day	52% 6% 12% 20% 9% 1	105246
	Night	52% 6% 12% 19% 9% 1	102467
Seeing	Day	24% 16% 29% 19% 8% 2	14538
	Night	23% 13% 29% 24% 9% 1	23602

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% 18% 6% 16% 6% 5% 5% 3 3 4 20%	2517
	11th to 20th	Day	14% 15% 6% 17% 7% 4 3 3 4 5% 21%	2520
	21st to end	Day	13% 16% 7% 14% 7% 6% 5% 4 5% 5% 19%	2808
February	1st to 10th	Day	12% 17% 5% 14% 8% 4 4 3 4 5% 23%	1710
	11th to 20th	Day	12% 18% 6% 12% 5% 5% 4 3 3 5% 27%	1688
	21st to end	Day	17% 16% 4 9% 7% 6% 3 3 5% 4 25%	1570
March	1st to 10th	Day	18% 16% 4 9% 6% 4 4 3 4 5% 26%	3116
	11th to 20th	Day	12% 18% 6% 11% 6% 5% 4 4 4 5% 25%	3411
	21st to end	Day	14% 9% 2 7% 6% 4 4 3 5% 6% 39%	4068
April	1st to 10th	Day	21% 14% 3 8% 4 3 3 3 4 5% 31%	2280
	11th to 20th	Day	23% 9% 3 7% 5% 4 3 3 5% 5% 34%	2254
	21st to end	Day	22% 10% 4 8% 4 5% 4 3 4 5% 31%	2429
May	1st to 10th	Day	21% 10% 3 8% 5% 4 5% 4 5% 6% 29%	4426
	11th to 20th	Day	19% 8% 3 7% 4 4 4 4 6% 8% 32%	4398
	21st to end	Day	18% 7% 3 7% 5% 4 5% 4 6% 7% 35%	4837
June	1st to 10th	Day	23% 8% 3 7% 5% 5% 5% 3 6% 7% 28%	2660
	11th to 20th	Day	16% 6% 3 7% 5% 5% 5% 4 6% 8% 36%	2660
	21st to end	Day	21% 7% 2 7% 5% 5% 6% 4 6% 8% 29%	2660
July	1st to 10th	Day	13% 6% 3 7% 6% 5% 6% 4 7% 10% 33%	4440
	11th to 20th	Day	15% 6% 2 7% 5% 5% 5% 5% 7% 8% 34%	4440
	21st to end	Day	12% 6% 2 6% 4 4 5% 3 5% 8% 45%	4814
August	1st to 10th	Day	15% 6% 3 8% 5% 5% 6% 4 7% 9% 32%	4423
	11th to 20th	Day	16% 7% 2 6% 5% 4 5% 4 6% 9% 37%	3975
	21st to end	Day	15% 5% 2 6% 5% 5% 4 4 6% 9% 38%	4180
September	1st to 10th	Day	15% 6% 2 6% 5% 4 4 4 5% 7% 42%	2280
	11th to 20th	Day	14% 5% 2 5% 4 4 4 3 5% 8% 45%	2256
	21st to end	Day	20% 7% 2 6% 4 3 4 3 5% 7% 40%	2063
October	1st to 10th	Day	22% 8% 3 6% 5% 4 4 3 5% 6% 34%	1900
	11th to 20th	Day	25% 9% 3 9% 4 5% 5% 4 4 6% 26%	1900
	21st to end	Day	25% 11% 3 7% 5% 4 4 3 5% 5% 27%	1900
November	1st to 10th	Day	15% 11% 4 7% 5% 5% 4 3 5% 8% 33%	1761
	11th to 20th	Day	19% 14% 4 10% 5% 5% 5% 3 5% 6% 25%	1626
	21st to end	Day	22% 15% 5% 10% 5% 4 4 4 4 5% 22%	1600
December	1st to 10th	Day	22% 20% 5% 12% 5% 4 4 4 4 5% 16%	1528
	11th to 20th	Day	20% 15% 6% 10% 5% 5% 4 3 4 5% 22%	1906
	21st to end	Day	25% 20% 6% 9% 5% 3 3 3 2 4 19%	2772
January	1st to 10th	Night	16% 18% 6% 10% 6% 4 4 3 5% 6% 23%	4429
	11th to 20th	Night	12% 15% 6% 13% 7% 5% 5% 3 5% 5% 24%	4440
	21st to end	Night	13% 16% 8% 13% 7% 6% 5% 3 4 5% 21%	4846
February	1st to 10th	Night	12% 14% 6% 12% 7% 5% 5% 4 5% 6% 24%	2470
	11th to 20th	Night	12% 15% 5% 11% 7% 5% 4 3 5% 5% 28%	2376
	21st to end	Night	14% 14% 5% 10% 6% 4 5% 4 5% 5% 29%	1884
March	1st to 10th	Night	19% 14% 4 8% 5% 4 4 3 4 5% 31%	3724
	11th to 20th	Night	15% 18% 4 9% 5% 4 4 4 4 6% 27%	3543
	21st to end	Night	15% 10% 3 8% 5% 4 4 4 5% 5% 38%	3563
April	1st to 10th	Night	21% 12% 2 6% 5% 5% 4 3 5% 6% 32%	1900
	11th to 20th	Night	20% 9% 3 7% 4 3 4 4 5% 6% 36%	1875
	21st to end	Night	20% 10% 4 7% 4 4 4 3 5% 6% 35%	1764
May	1st to 10th	Night	20% 11% 3 8% 5% 5% 4 3 5% 6% 30%	2514
	11th to 20th	Night	20% 7% 2 7% 4 4 4 3 5% 6% 38%	2495
	21st to end	Night	17% 6% 3 7% 5% 5% 4 4 6% 7% 36%	2738
June	1st to 10th	Night	15% 8% 3 7% 4 5% 6% 4 7% 9% 32%	1520
	11th to 20th	Night	15% 7% 3 7% 4 4 4 4 5% 7% 41%	1520
	21st to end	Night	20% 6% 3 7% 4 5% 4 4 5% 6% 37%	1520
July	1st to 10th	Night	13% 6% 2 7% 6% 6% 6% 4 6% 7% 37%	2520
	11th to 20th	Night	16% 5% 2 6% 4 3 4 3 6% 8% 42%	2520
	21st to end	Night	11% 5% 2 5% 4 4 5% 4 6% 7% 47%	2739
August	1st to 10th	Night	12% 6% 3 8% 5% 4 5% 4 6% 8% 39%	2506
	11th to 20th	Night	16% 7% 2 5% 4 3 5% 3 5% 7% 42%	2806
	21st to end	Night	15% 6% 2 6% 4 4 5% 3 5% 7% 43%	3476
September	1st to 10th	Night	13% 6% 1 6% 4 4 5% 3 6% 6% 47%	1900
	11th to 20th	Night	15% 5% 2 4 3 4 3 3 5% 6% 50%	1924
	21st to end	Night	17% 6% 2 6% 4 3 3 4 5% 6% 44%	2114
October	1st to 10th	Night	19% 9% 2 6% 4 5% 3 4 5% 6% 38%	2280
	11th to 20th	Night	20% 9% 3 7% 5% 5% 4 3 5% 7% 32%	2280
	21st to end	Night	22% 10% 4 8% 5% 5% 4 3 4 5% 30%	2698
November	1st to 10th	Night	18% 11% 4 7% 5% 4 4 4 5% 6% 32%	2537
	11th to 20th	Night	18% 12% 3 8% 5% 6% 4 4 5% 5% 29%	2770
	21st to end	Night	19% 16% 5% 9% 6% 5% 5% 3 5% 5% 23%	2800
December	1st to 10th	Night	20% 19% 5% 10% 6% 5% 4 3 4 5% 19%	2686
	11th to 20th	Night	22% 15% 4 10% 5% 3 4 3 3 5% 26%	3288
	21st to end	Night	26% 21% 5% 9% 4 4 3 3 3 4 20%	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	70% 6% 8% 11% 5% 1	2518
	11th to 20th	Day	65% 6% 9% 13% 7% 1	2520
	21st to end	Day	67% 6% 9% 11% 6% 1	2808
February	1st to 10th	Day	64% 5% 7% 17% 6% 2	1710
	11th to 20th	Day	61% 5% 9% 14% 10% 1	1697
	21st to end	Day	62% 5% 8% 14% 10% 1	1570
March	1st to 10th	Day	61% 6% 7% 15% 10% 1	3119
	11th to 20th	Day	61% 5% 11% 12% 9% 2	3411
	21st to end	Day	45% 4 9% 21% 19% 2	4068
April	1st to 10th	Day	56% 4 8% 18% 12% 3	2280
	11th to 20th	Day	53% 4 7% 20% 14% 2	2254
	21st to end	Day	56% 5% 8% 15% 13% 4	2429
May	1st to 10th	Day	53% 7% 8% 21% 9% 2	4440
	11th to 20th	Day	48% 8% 15% 18% 10% 1	4402
	21st to end	Day	46% 7% 11% 20% 14% 1	4837
June	1st to 10th	Day	55% 6% 9% 18% 11% 1	2660
	11th to 20th	Day	44% 6% 13% 23% 12% 3	2660
	21st to end	Day	51% 8% 13% 18% 9% 1	2660
July	1st to 10th	Day	44% 7% 15% 24% 9%	4370
	11th to 20th	Day	43% 8% 15% 26% 8%	4365
	21st to end	Day	37% 7% 14% 32% 10%	4661
August	1st to 10th	Day	47% 7% 17% 22% 7%	4409
	11th to 20th	Day	42% 7% 15% 28% 7%	4014
	21st to end	Day	41% 7% 16% 23% 12% 1	4180
September	1st to 10th	Day	41% 6% 13% 27% 13%	2280
	11th to 20th	Day	37% 6% 14% 31% 11% 1	2256
	21st to end	Day	44% 6% 14% 26% 10%	2063
October	1st to 10th	Day	49% 7% 11% 26% 7%	3160
	11th to 20th	Day	49% 7% 13% 23% 7%	3140
	21st to end	Day	51% 6% 20% 17% 6%	3112
November	1st to 10th	Day	50% 6% 15% 22% 6% 1	1761
	11th to 20th	Day	61% 6% 11% 12% 9% 1	1626
	21st to end	Day	66% 5% 12% 11% 5% 1	1600
December	1st to 10th	Day	70% 6% 10% 10% 4	1528
	11th to 20th	Day	65% 7% 11% 13% 5%	1906
	21st to end	Day	71% 4 6% 14% 5%	2772
January	1st to 10th	Night	63% 6% 16% 11% 3	4429
	11th to 20th	Night	60% 9% 12% 13% 5% 1	4440
	21st to end	Night	67% 7% 10% 9% 7% 1	4846
February	1st to 10th	Night	61% 5% 9% 17% 7% 1	2470
	11th to 20th	Night	59% 4 9% 18% 9% 1	2378
	21st to end	Night	56% 6% 9% 17% 11% 1	1884
March	1st to 10th	Night	57% 4 10% 15% 10% 3	3734
	11th to 20th	Night	57% 5% 12% 16% 8% 2	3544
	21st to end	Night	48% 4 8% 21% 16% 3	3563
April	1st to 10th	Night	53% 5% 9% 17% 14% 2	1900
	11th to 20th	Night	48% 6% 8% 21% 15% 1	1875
	21st to end	Night	51% 4 10% 18% 14% 3	1764
May	1st to 10th	Night	53% 8% 9% 19% 9% 2	2520
	11th to 20th	Night	46% 7% 14% 19% 12% 2	2496
	21st to end	Night	47% 7% 10% 20% 15% 2	2739
June	1st to 10th	Night	46% 8% 12% 22% 11%	1520
	11th to 20th	Night	43% 5% 12% 24% 14% 2	1520
	21st to end	Night	46% 9% 11% 20% 13% 1	1520
July	1st to 10th	Night	44% 8% 17% 20% 11% 1	2480
	11th to 20th	Night	39% 7% 16% 29% 7%	2472
	21st to end	Night	34% 7% 17% 27% 14%	2651
August	1st to 10th	Night	41% 9% 15% 27% 8%	2496
	11th to 20th	Night	40% 7% 17% 30% 7%	2832
	21st to end	Night	41% 7% 15% 23% 12% 2	3476
September	1st to 10th	Night	37% 6% 13% 29% 14% 1	1900
	11th to 20th	Night	35% 6% 14% 34% 10% 1	1924
	21st to end	Night	40% 5% 13% 30% 11%	2114
October	1st to 10th	Night	41% 6% 14% 27% 11%	3800
	11th to 20th	Night	44% 7% 16% 25% 9%	3779
	21st to end	Night	48% 5% 19% 17% 10%	4436
November	1st to 10th	Night	53% 6% 14% 19% 8%	2537
	11th to 20th	Night	57% 6% 12% 15% 10% 1	2770
	21st to end	Night	63% 7% 11% 15% 4	2800
December	1st to 10th	Night	68% 6% 10% 12% 4	2686
	11th to 20th	Night	62% 6% 8% 16% 7% 1	3288
	21st to end	Night	70% 5% 6% 14% 5%	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	26% 22% 28% 19% 6%	180
	11th to 20th	Day	33% 14% 33% 13% 6%	180
	21st to end	Day	22% 17% 34% 22% 5%	209
February	1st to 10th	Day	31% 26% 30% 10% 3	270
	11th to 20th	Day	29% 29% 31% 11%	295
	21st to end	Day	29% 23% 31% 16% 1	382
March	1st to 10th	Day	27% 21% 31% 15% 6%	460
	11th to 20th	Day	26% 22% 33% 14% 4 1	460
	21st to end	Day	31% 22% 25% 15% 6% 1	506
April	1st to 10th	Day	30% 19% 29% 14% 6% 1	460
	11th to 20th	Day	35% 18% 23% 13% 9% 2	452
	21st to end	Day	31% 20% 31% 11% 6%	460
May	1st to 10th	Day	27% 18% 31% 16% 6% 2	463
	11th to 20th	Day	22% 18% 29% 21% 8% 2	487
	21st to end	Day	24% 16% 32% 18% 9% 2	529
June	1st to 10th	Day	26% 11% 32% 22% 8%	490
	11th to 20th	Day	18% 18% 32% 21% 9% 2	490
	21st to end	Day	24% 13% 29% 22% 11% 1	490
July	1st to 10th	Day	15% 13% 30% 28% 9% 4	485
	11th to 20th	Day	15% 11% 33% 27% 11% 2	484
	21st to end	Day	13% 9% 33% 31% 11% 2	532
August	1st to 10th	Day	15% 8% 29% 35% 11% 2	486
	11th to 20th	Day	14% 9% 26% 28% 15% 8%	479
	21st to end	Day	18% 12% 29% 22% 12% 7%	539
September	1st to 10th	Day	16% 11% 32% 22% 13% 6%	490
	11th to 20th	Day	13% 11% 24% 24% 19% 9%	490
	21st to end	Day	21% 15% 26% 19% 14% 5%	490
October	1st to 10th	Day	26% 17% 22% 18% 14% 3	490
	11th to 20th	Day	29% 22% 26% 14% 8% 1	490
	21st to end	Day	32% 15% 30% 17% 5%	439
November	1st to 10th	Day	32% 15% 29% 18% 5% 1	395
	11th to 20th	Day	28% 20% 35% 11% 6% 1	226
	21st to end	Day	33% 21% 29% 15% 3 1	200
December	1st to 10th	Day	32% 13% 35% 18% 2	182
	11th to 20th	Day	28% 22% 37% 11% 2 1	180
	21st to end	Day	32% 25% 26% 13% 3 1	198
January	1st to 10th	Night	28% 17% 36% 16% 4	760
	11th to 20th	Night	29% 16% 29% 20% 5%	760
	21st to end	Night	20% 15% 36% 22% 6% 1	836
February	1st to 10th	Night	19% 18% 35% 22% 5%	760
	11th to 20th	Night	20% 20% 38% 18% 4	743
	21st to end	Night	23% 17% 32% 24% 3 1	628
March	1st to 10th	Night	24% 17% 33% 21% 5%	760
	11th to 20th	Night	25% 18% 31% 20% 5% 1	760
	21st to end	Night	24% 16% 31% 22% 7%	836
April	1st to 10th	Night	28% 16% 29% 23% 4	760
	11th to 20th	Night	26% 16% 30% 20% 6%	751
	21st to end	Night	26% 15% 30% 22% 7%	624
May	1st to 10th	Night	25% 13% 25% 28% 8% 2	380
	11th to 20th	Night	22% 11% 29% 29% 10%	374
	21st to end	Night	16% 10% 37% 24% 11% 1	411
June	1st to 10th	Night	17% 9% 31% 34% 8%	380
	11th to 20th	Night	19% 8% 28% 32% 12% 1	380
	21st to end	Night	21% 6% 26% 31% 15% 1	380
July	1st to 10th	Night	9% 6% 33% 36% 15%	370
	11th to 20th	Night	15% 4 21% 42% 17% 1	368
	21st to end	Night	11% 5% 27% 39% 16% 2	416
August	1st to 10th	Night	13% 5% 20% 40% 20% 1	378
	11th to 20th	Night	13% 4 20% 35% 25% 3	571
	21st to end	Night	16% 8% 24% 32% 18% 2	836
September	1st to 10th	Night	15% 6% 30% 31% 16% 1	760
	11th to 20th	Night	17% 8% 21% 29% 23% 2	760
	21st to end	Night	21% 9% 24% 27% 17% 2	760
October	1st to 10th	Night	22% 11% 27% 24% 15% 1	760
	11th to 20th	Night	26% 14% 28% 23% 8% 1	760
	21st to end	Night	27% 14% 29% 25% 5%	836
November	1st to 10th	Night	27% 14% 27% 23% 8% 1	780
	11th to 20th	Night	25% 17% 31% 16% 11%	800
	21st to end	Night	30% 19% 27% 19% 6%	800
December	1st to 10th	Night	30% 16% 31% 18% 5%	768
	11th to 20th	Night	29% 17% 31% 17% 4 1	760
	21st to end	Night	35% 15% 31% 16% 4	836

Page generated at 2024-11-29 10:43:04. Version ac07

Copyright © 2024 Attilla Danko.