Mont Ham-Nord
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mont Ham-Nord clear sky chart from 2005-11-06 to 2025-02-21.

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% 13% 5% 10% 6% 5% 5% 3 5% 6% 26%	108003
	Night	17% 14% 5% 11% 6% 5% 4 3 4 5% 25%	110538
Transparency	Day	58% 6% 11% 17% 7% 1	111506
	Night	61% 5% 10% 16% 7% 1	115200
Seeing	Day	27% 17% 29% 18% 7% 2	15077
	Night	26% 15% 27% 23% 8% 1	24121

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	13% 19% 9% 20% 10% 7% 6% 3 2 2 8%	3597
	11th to 20th	Day	8% 15% 8% 26% 16% 5% 3 2 2 2 13%	3570
	21st to end	Day	8% 15% 10% 15% 7% 9% 7% 4 4 4 17%	3960
February	1st to 10th	Day	12% 20% 6% 15% 10% 6% 4 3 3 4 17%	1636
	11th to 20th	Day	14% 19% 9% 13% 9% 6% 4 3 3 4 16%	1948
	21st to end	Day	13% 20% 6% 12% 7% 6% 5% 3 4 5% 20%	1570
March	1st to 10th	Day	18% 16% 5% 12% 7% 4 3 3 4 5% 23%	3116
	11th to 20th	Day	15% 21% 7% 14% 5% 4 4 2 3 4 20%	3306
	21st to end	Day	17% 15% 5% 11% 4 4 3 2 3 4 32%	4088
April	1st to 10th	Day	22% 18% 4 10% 5% 4 3 2 4 3 25%	2280
	11th to 20th	Day	20% 14% 3 7% 5% 4 3 3 4 5% 32%	2314
	21st to end	Day	23% 14% 4 8% 5% 4 3 3 4 5% 27%	2470
May	1st to 10th	Day	24% 9% 3 8% 5% 5% 4 3 5% 6% 28%	4184
	11th to 20th	Day	19% 9% 3 7% 5% 4 6% 4 6% 8% 28%	4398
	21st to end	Day	17% 8% 3 8% 5% 6% 6% 4 7% 8% 29%	4837
June	1st to 10th	Day	25% 10% 2 7% 4 5% 5% 4 6% 8% 26%	2660
	11th to 20th	Day	19% 7% 2 6% 5% 5% 5% 4 7% 8% 32%	2820
	21st to end	Day	26% 9% 3 8% 5% 5% 4 3 6% 6% 25%	2660
July	1st to 10th	Day	16% 8% 3 8% 6% 6% 6% 5% 6% 7% 29%	4440
	11th to 20th	Day	17% 9% 3 7% 5% 6% 5% 5% 7% 7% 30%	4440
	21st to end	Day	17% 7% 2 6% 4 4 5% 4 6% 7% 38%	4814
August	1st to 10th	Day	19% 7% 2 8% 6% 5% 6% 5% 7% 8% 26%	4377
	11th to 20th	Day	20% 8% 2 8% 5% 6% 6% 5% 7% 8% 24%	4045
	21st to end	Day	21% 8% 2 6% 5% 5% 4 4 5% 6% 34%	4257
September	1st to 10th	Day	18% 7% 3 7% 4 5% 4 3 6% 6% 37%	2280
	11th to 20th	Day	20% 7% 2 5% 4 3 3 4 5% 7% 40%	2119
	21st to end	Day	20% 9% 3 6% 4 4 4 4 7% 8% 33%	2090
October	1st to 10th	Day	23% 11% 3 6% 4 4 5% 3 5% 7% 29%	2080
	11th to 20th	Day	21% 15% 4 9% 5% 5% 5% 3 4 6% 23%	1763
	21st to end	Day	26% 18% 5% 8% 4 4 3 2 4 6% 21%	1881
November	1st to 10th	Day	19% 19% 4 8% 5% 3 4 3 4 4 28%	1761
	11th to 20th	Day	18% 19% 6% 11% 6% 3 3 3 4 5% 23%	1800
	21st to end	Day	18% 24% 7% 11% 4 4 4 3 4 4 17%	1601
December	1st to 10th	Day	17% 20% 9% 14% 8% 6% 4 2 3 3 13%	2280
	11th to 20th	Day	18% 17% 8% 13% 6% 4 4 2 3 4 22%	2618
	21st to end	Day	18% 21% 7% 12% 5% 4 4 3 4 4 18%	3943
January	1st to 10th	Night	12% 19% 10% 20% 10% 7% 3 2 2 3 12%	6349
	11th to 20th	Night	8% 20% 8% 22% 12% 7% 5% 3 2 3 10%	6315
	21st to end	Night	7% 15% 8% 15% 8% 8% 7% 4 5% 5% 19%	6996
February	1st to 10th	Night	12% 16% 7% 14% 9% 6% 4 3 4 5% 20%	2760
	11th to 20th	Night	12% 17% 7% 15% 8% 6% 5% 3 4 4 19%	2338
	21st to end	Night	14% 15% 5% 12% 7% 5% 4 3 5% 3 26%	1885
March	1st to 10th	Night	21% 16% 4 7% 5% 3 5% 3 3 4 28%	3724
	11th to 20th	Night	15% 19% 7% 15% 6% 4 4 3 3 3 22%	3653
	21st to end	Night	15% 16% 5% 10% 7% 4 4 3 3 4 29%	3540
April	1st to 10th	Night	23% 13% 4 9% 4 3 4 3 4 4 29%	1900
	11th to 20th	Night	21% 11% 3 7% 5% 4 4 3 5% 5% 33%	1814
	21st to end	Night	23% 12% 4 7% 4 4 4 4 4 5% 29%	1710
May	1st to 10th	Night	24% 9% 3 7% 5% 5% 4 4 5% 6% 28%	2784
	11th to 20th	Night	22% 9% 3 6% 4 4 3 3 5% 7% 33%	2495
	21st to end	Night	18% 7% 2 6% 4 4 5% 4 6% 8% 35%	2738
June	1st to 10th	Night	23% 10% 3 5% 5% 4 4 3 7% 8% 27%	1517
	11th to 20th	Night	20% 6% 2 5% 5% 4 4 3 6% 8% 36%	1332
	21st to end	Night	21% 9% 3 7% 6% 5% 5% 3 5% 7% 30%	1520
July	1st to 10th	Night	12% 10% 3 9% 6% 6% 4 4 6% 8% 31%	2520
	11th to 20th	Night	19% 8% 3 6% 5% 5% 4 4 5% 7% 35%	2520
	21st to end	Night	16% 7% 2 6% 5% 4 5% 3 6% 7% 39%	2739
August	1st to 10th	Night	23% 8% 3 8% 4 4 4 4 5% 7% 30%	2520
	11th to 20th	Night	18% 10% 4 10% 5% 5% 5% 4 5% 7% 29%	2782
	21st to end	Night	18% 8% 2 8% 4 4 4 3 5% 6% 37%	3397
September	1st to 10th	Night	18% 8% 2 6% 4 4 5% 3 5% 6% 39%	1900
	11th to 20th	Night	17% 6% 2 5% 3 2 3 3 5% 6% 46%	2060
	21st to end	Night	19% 8% 2 6% 4 3 4 3 3 6% 41%	2090
October	1st to 10th	Night	18% 9% 3 7% 5% 3 4 3 5% 6% 35%	2099
	11th to 20th	Night	23% 12% 3 7% 5% 4 4 3 4 5% 29%	2416
	21st to end	Night	25% 14% 3 8% 4 4 4 3 4 5% 25%	2717
November	1st to 10th	Night	20% 15% 4 9% 5% 4 4 4 4 5% 26%	2537
	11th to 20th	Night	18% 14% 6% 11% 5% 4 4 2 4 4 27%	2600
	21st to end	Night	19% 19% 7% 12% 6% 4 3 3 3 4 21%	2789
December	1st to 10th	Night	15% 20% 10% 20% 10% 4 3 2 3 3 11%	4910
	11th to 20th	Night	20% 19% 6% 15% 6% 4 3 2 3 3 17%	5576
	21st to end	Night	18% 21% 5% 12% 5% 4 3 2 3 4 23%	6996

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	84% 4 6% 6% 1	3598
	11th to 20th	Day	81% 3 4 10% 3 1	3600
	21st to end	Day	71% 5% 6% 9% 9% 1	3960
February	1st to 10th	Day	72% 4 5% 10% 6% 1	1636
	11th to 20th	Day	73% 3 8% 10% 5% 1	1957
	21st to end	Day	67% 4 8% 14% 6% 2	1570
March	1st to 10th	Day	62% 7% 7% 12% 9% 2	3119
	11th to 20th	Day	67% 5% 9% 11% 7% 1	3306
	21st to end	Day	58% 4 7% 16% 14% 2	4088
April	1st to 10th	Day	64% 5% 9% 14% 8% 2	2280
	11th to 20th	Day	54% 5% 9% 19% 12% 1	2314
	21st to end	Day	59% 5% 8% 16% 10% 2	2470
May	1st to 10th	Day	54% 8% 11% 18% 8% 1	4198
	11th to 20th	Day	50% 10% 19% 14% 6% 1	4402
	21st to end	Day	48% 9% 12% 20% 11%	4837
June	1st to 10th	Day	54% 8% 11% 19% 7% 1	2660
	11th to 20th	Day	48% 7% 15% 21% 10% 1	2820
	21st to end	Day	58% 7% 10% 17% 7%	2660
July	1st to 10th	Day	50% 8% 14% 21% 7%	4370
	11th to 20th	Day	51% 6% 16% 24% 4	4365
	21st to end	Day	44% 7% 12% 29% 7%	4661
August	1st to 10th	Day	53% 7% 16% 20% 4	4363
	11th to 20th	Day	54% 9% 16% 16% 4	4084
	21st to end	Day	49% 6% 14% 18% 12% 2	4257
September	1st to 10th	Day	45% 7% 15% 23% 9% 1	2280
	11th to 20th	Day	42% 6% 13% 27% 11%	2119
	21st to end	Day	48% 7% 12% 23% 10%	2090
October	1st to 10th	Day	53% 6% 14% 22% 6%	3457
	11th to 20th	Day	57% 5% 12% 24% 3	2901
	21st to end	Day	57% 3 16% 17% 6%	3081
November	1st to 10th	Day	60% 5% 11% 17% 7%	1761
	11th to 20th	Day	64% 5% 9% 13% 8% 1	1800
	21st to end	Day	72% 5% 10% 11% 3	1601
December	1st to 10th	Day	77% 3 8% 8% 4	2280
	11th to 20th	Day	69% 3 6% 15% 7%	2618
	21st to end	Day	70% 3 6% 10% 9% 1	3943
January	1st to 10th	Night	79% 5% 7% 7% 3	6349
	11th to 20th	Night	81% 5% 5% 7% 2	6360
	21st to end	Night	66% 6% 7% 11% 10% 1	6996
February	1st to 10th	Night	68% 4 9% 12% 6% 1	2760
	11th to 20th	Night	69% 5% 8% 11% 7%	2340
	21st to end	Night	62% 5% 8% 14% 10% 1	1885
March	1st to 10th	Night	60% 6% 10% 15% 8% 2	3734
	11th to 20th	Night	68% 5% 6% 12% 7% 1	3654
	21st to end	Night	61% 4 8% 17% 9% 2	3540
April	1st to 10th	Night	58% 5% 9% 15% 12% 1	1900
	11th to 20th	Night	52% 6% 9% 20% 11% 2	1814
	21st to end	Night	56% 7% 9% 16% 10% 2	1710
May	1st to 10th	Night	53% 9% 12% 17% 8% 1	2790
	11th to 20th	Night	48% 8% 14% 20% 8% 1	2496
	21st to end	Night	44% 8% 14% 17% 15% 1	2739
June	1st to 10th	Night	53% 8% 12% 18% 8%	1517
	11th to 20th	Night	44% 7% 12% 24% 11% 2	1332
	21st to end	Night	54% 7% 12% 18% 9%	1520
July	1st to 10th	Night	50% 7% 16% 18% 9%	2480
	11th to 20th	Night	48% 7% 18% 21% 6%	2472
	21st to end	Night	44% 7% 16% 26% 6%	2651
August	1st to 10th	Night	53% 6% 14% 22% 4	2510
	11th to 20th	Night	54% 9% 14% 18% 6%	2809
	21st to end	Night	47% 6% 12% 22% 12%	3397
September	1st to 10th	Night	45% 7% 13% 24% 10% 1	1900
	11th to 20th	Night	38% 6% 16% 30% 10% 1	2060
	21st to end	Night	44% 6% 12% 25% 12% 1	2090
October	1st to 10th	Night	51% 4 12% 24% 9%	3502
	11th to 20th	Night	55% 5% 12% 24% 5%	4017
	21st to end	Night	53% 4 15% 18% 8% 2	4467
November	1st to 10th	Night	59% 6% 12% 17% 5% 1	2537
	11th to 20th	Night	61% 5% 11% 14% 8% 2	2600
	21st to end	Night	68% 5% 10% 12% 4	2789
December	1st to 10th	Night	82% 3 7% 7% 2	4910
	11th to 20th	Night	73% 4 5% 12% 6%	5577
	21st to end	Night	67% 4 6% 14% 8%	6996

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	29% 25% 35% 10% 1 1	200
	11th to 20th	Day	30% 24% 33% 12% 3	200
	21st to end	Day	25% 27% 30% 15% 3	220
February	1st to 10th	Day	33% 29% 29% 8% 1	221
	11th to 20th	Day	31% 27% 31% 9% 2	496
	21st to end	Day	30% 25% 26% 18% 2	382
March	1st to 10th	Day	27% 25% 28% 16% 4	460
	11th to 20th	Day	28% 26% 27% 13% 4 1	460
	21st to end	Day	31% 22% 27% 12% 8% 1	506
April	1st to 10th	Day	37% 18% 26% 13% 4 2	460
	11th to 20th	Day	32% 21% 23% 15% 7% 2	452
	21st to end	Day	34% 19% 28% 12% 4 2	460
May	1st to 10th	Day	31% 19% 27% 17% 5% 1	463
	11th to 20th	Day	24% 15% 31% 20% 8% 2	487
	21st to end	Day	23% 21% 32% 17% 6% 1	529
June	1st to 10th	Day	28% 18% 30% 16% 7% 1	490
	11th to 20th	Day	23% 13% 29% 23% 11%	650
	21st to end	Day	27% 14% 33% 17% 7% 2	490
July	1st to 10th	Day	20% 10% 34% 25% 9% 1	485
	11th to 20th	Day	20% 11% 39% 21% 7% 1	484
	21st to end	Day	22% 10% 33% 27% 6% 1	532
August	1st to 10th	Day	22% 12% 29% 24% 11% 2	486
	11th to 20th	Day	22% 8% 27% 25% 16% 1	479
	21st to end	Day	23% 13% 25% 21% 12% 6%	539
September	1st to 10th	Day	21% 12% 31% 21% 10% 5%	490
	11th to 20th	Day	22% 11% 23% 24% 15% 7%	490
	21st to end	Day	21% 13% 28% 24% 10% 4	490
October	1st to 10th	Day	25% 13% 27% 20% 11% 3	490
	11th to 20th	Day	31% 16% 27% 13% 12% 1	417
	21st to end	Day	38% 17% 25% 15% 4	429
November	1st to 10th	Day	35% 15% 29% 17% 4	395
	11th to 20th	Day	32% 18% 30% 15% 6% 1	400
	21st to end	Day	32% 22% 31% 12% 3	225
December	1st to 10th	Day	35% 20% 29% 13% 4 1	200
	11th to 20th	Day	34% 27% 26% 11% 2 1	200
	21st to end	Day	36% 22% 27% 10% 4 1	220
January	1st to 10th	Night	26% 24% 32% 16% 3	800
	11th to 20th	Night	26% 22% 31% 17% 4	800
	21st to end	Night	19% 21% 34% 21% 4 1	880
February	1st to 10th	Night	22% 23% 32% 20% 4	800
	11th to 20th	Night	25% 22% 34% 17% 3	783
	21st to end	Night	24% 21% 32% 19% 3	629
March	1st to 10th	Night	25% 18% 33% 21% 3	760
	11th to 20th	Night	27% 21% 27% 19% 5% 1	760
	21st to end	Night	25% 16% 28% 24% 6% 1	836
April	1st to 10th	Night	32% 15% 28% 21% 5%	760
	11th to 20th	Night	28% 16% 27% 22% 6%	690
	21st to end	Night	30% 15% 28% 20% 6% 1	570
May	1st to 10th	Night	28% 12% 29% 23% 7% 1	546
	11th to 20th	Night	21% 11% 31% 29% 6% 1	374
	21st to end	Night	24% 9% 31% 28% 8%	411
June	1st to 10th	Night	28% 9% 26% 28% 8% 1	380
	11th to 20th	Night	21% 7% 24% 36% 11%	380
	21st to end	Night	23% 7% 26% 33% 11% 1	380
July	1st to 10th	Night	16% 7% 28% 34% 14% 1	370
	11th to 20th	Night	17% 6% 25% 37% 14% 1	368
	21st to end	Night	17% 6% 23% 39% 15%	416
August	1st to 10th	Night	20% 5% 17% 38% 19% 1	379
	11th to 20th	Night	19% 6% 20% 36% 18% 1	562
	21st to end	Night	21% 5% 22% 31% 19% 2	783
September	1st to 10th	Night	23% 7% 24% 31% 13% 2	760
	11th to 20th	Night	20% 8% 20% 29% 20% 3	760
	21st to end	Night	23% 10% 25% 26% 15% 2	760
October	1st to 10th	Night	24% 11% 26% 25% 12% 1	760
	11th to 20th	Night	29% 14% 24% 23% 8% 2	760
	21st to end	Night	33% 16% 27% 20% 4	836
November	1st to 10th	Night	30% 17% 27% 20% 6%	780
	11th to 20th	Night	27% 19% 29% 17% 9% 1	800
	21st to end	Night	32% 21% 22% 19% 5%	810
December	1st to 10th	Night	34% 19% 25% 16% 5%	900
	11th to 20th	Night	29% 23% 25% 17% 5%	898
	21st to end	Night	34% 18% 26% 16% 5%	880

Page generated at 2025-02-18 03:26:26. Version ac07

Copyright © 2025 Attilla Danko.