ZEC des Nymphes
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the ZEC des Nymphes clear sky chart from 2005-11-06 to 2024-11-04.

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	16% 11% 4 9% 5% 5% 5% 4 5% 7% 30%	101592
	Night	15% 11% 4 9% 5% 5% 4 4 5% 6% 32%	97432
Transparency	Day	51% 6% 12% 20% 10% 1	105042
	Night	50% 6% 12% 20% 10% 1	102071
Seeing	Day	24% 19% 32% 17% 7% 2	14507
	Night	22% 15% 31% 24% 8% 1	23414

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	12% 16% 5% 12% 6% 5% 4 3 4 5% 26%	2517
	11th to 20th	Day	10% 16% 7% 15% 8% 5% 3 3 4 4 26%	2520
	21st to end	Day	10% 12% 7% 15% 7% 6% 6% 4 5% 8% 22%	2772
February	1st to 10th	Day	10% 19% 5% 12% 8% 6% 4 3 4 5% 24%	1629
	11th to 20th	Day	11% 16% 5% 12% 6% 5% 5% 3 5% 5% 27%	1752
	21st to end	Day	14% 17% 6% 10% 5% 5% 5% 3 4 5% 25%	1570
March	1st to 10th	Day	15% 19% 4 9% 7% 5% 4 4 4 4 24%	3116
	11th to 20th	Day	10% 17% 6% 14% 6% 5% 5% 3 4 5% 25%	3273
	21st to end	Day	12% 14% 3 8% 4 4 4 4 5% 6% 36%	4166
April	1st to 10th	Day	18% 15% 4 9% 5% 3 4 3 4 6% 29%	2280
	11th to 20th	Day	22% 9% 3 7% 5% 4 4 3 5% 5% 33%	2254
	21st to end	Day	20% 12% 4 8% 5% 4 4 4 5% 5% 30%	2460
May	1st to 10th	Day	20% 10% 4 8% 5% 4 4 4 5% 6% 30%	4410
	11th to 20th	Day	17% 7% 3 8% 5% 5% 5% 4 7% 9% 31%	4398
	21st to end	Day	17% 8% 3 8% 6% 6% 6% 4 5% 6% 32%	4837
June	1st to 10th	Day	21% 9% 3 8% 6% 5% 5% 4 6% 7% 26%	2660
	11th to 20th	Day	15% 7% 3 7% 6% 5% 5% 4 6% 8% 32%	2660
	21st to end	Day	23% 9% 3 8% 7% 5% 5% 4 5% 7% 25%	2660
July	1st to 10th	Day	14% 8% 3 8% 7% 6% 6% 5% 8% 8% 29%	4440
	11th to 20th	Day	14% 6% 2 6% 6% 6% 6% 5% 8% 8% 32%	4440
	21st to end	Day	12% 6% 3 7% 5% 5% 5% 4 7% 7% 39%	4814
August	1st to 10th	Day	14% 5% 3 8% 5% 7% 7% 5% 7% 8% 30%	4423
	11th to 20th	Day	16% 7% 3 7% 5% 5% 6% 5% 7% 9% 31%	4089
	21st to end	Day	15% 7% 3 7% 5% 4 5% 4 7% 8% 35%	4180
September	1st to 10th	Day	15% 5% 2 6% 5% 5% 5% 4 5% 9% 40%	2280
	11th to 20th	Day	14% 6% 2 6% 5% 4 5% 4 5% 6% 44%	2195
	21st to end	Day	20% 8% 3 5% 4 4 5% 3 4 7% 38%	2090
October	1st to 10th	Day	22% 9% 3 6% 4 5% 4 4 5% 7% 31%	1965
	11th to 20th	Day	21% 11% 4 9% 5% 5% 5% 3 5% 5% 25%	1837
	21st to end	Day	24% 12% 3 7% 4 5% 4 4 5% 6% 26%	1881
November	1st to 10th	Day	15% 13% 4 7% 6% 5% 4 4 5% 5% 32%	1698
	11th to 20th	Day	19% 13% 5% 9% 5% 4 5% 5% 5% 6% 25%	1608
	21st to end	Day	19% 17% 4 7% 5% 5% 6% 3 4 5% 24%	1520
December	1st to 10th	Day	23% 17% 4 10% 4 3 4 4 4 4 21%	1520
	11th to 20th	Day	20% 14% 5% 10% 6% 4 4 3 4 6% 24%	1906
	21st to end	Day	19% 19% 5% 11% 5% 4 4 3 4 5% 22%	2772
January	1st to 10th	Night	13% 17% 6% 11% 6% 4 5% 3 5% 6% 24%	4429
	11th to 20th	Night	9% 12% 6% 14% 8% 6% 5% 4 4 6% 27%	4440
	21st to end	Night	9% 13% 7% 15% 8% 7% 6% 4 4 6% 22%	4884
February	1st to 10th	Night	11% 14% 5% 11% 6% 6% 5% 4 5% 6% 27%	2546
	11th to 20th	Night	10% 14% 5% 11% 6% 6% 4 4 5% 6% 29%	2314
	21st to end	Night	13% 13% 4 9% 6% 5% 5% 4 5% 6% 31%	1884
March	1st to 10th	Night	18% 16% 4 8% 5% 4 5% 3 4 6% 27%	3724
	11th to 20th	Night	12% 19% 6% 11% 5% 5% 4 3 4 5% 26%	3671
	21st to end	Night	12% 9% 4 11% 6% 5% 4 4 5% 5% 34%	3466
April	1st to 10th	Night	20% 13% 2 8% 5% 5% 5% 3 5% 5% 30%	1900
	11th to 20th	Night	18% 7% 2 7% 5% 4 4 4 5% 7% 36%	1875
	21st to end	Night	20% 11% 3 6% 4 3 5% 3 5% 5% 35%	1720
May	1st to 10th	Night	18% 11% 3 6% 6% 5% 4 3 5% 7% 31%	2560
	11th to 20th	Night	20% 8% 2 5% 4 4 4 3 5% 7% 38%	2495
	21st to end	Night	18% 7% 3 8% 6% 5% 5% 4 6% 7% 31%	2738
June	1st to 10th	Night	18% 8% 3 6% 5% 4 5% 4 5% 8% 34%	1520
	11th to 20th	Night	17% 8% 3 5% 4 5% 4 4 6% 6% 37%	1520
	21st to end	Night	19% 8% 3 5% 5% 5% 5% 4 5% 7% 34%	1520
July	1st to 10th	Night	13% 6% 2 8% 5% 5% 7% 5% 7% 9% 33%	2520
	11th to 20th	Night	15% 5% 2 6% 4 4 5% 4 6% 8% 42%	2520
	21st to end	Night	11% 5% 2 5% 3 3 4 4 7% 8% 49%	2739
August	1st to 10th	Night	12% 6% 2 7% 5% 5% 5% 5% 6% 8% 38%	2506
	11th to 20th	Night	16% 7% 2 6% 4 4 4 3 5% 7% 41%	2705
	21st to end	Night	17% 8% 3 6% 3 4 4 4 5% 7% 40%	3476
September	1st to 10th	Night	12% 6% 2 6% 4 5% 4 3 5% 7% 46%	1900
	11th to 20th	Night	15% 5% 1 5% 3 3 3 4 6% 6% 49%	1984
	21st to end	Night	17% 7% 2 5% 4 3 3 3 5% 7% 44%	2090
October	1st to 10th	Night	16% 10% 2 6% 5% 4 4 3 5% 5% 40%	2213
	11th to 20th	Night	20% 9% 3 8% 5% 4 4 3 6% 7% 32%	2342
	21st to end	Night	22% 9% 4 8% 5% 5% 4 3 5% 7% 28%	2717
November	1st to 10th	Night	17% 10% 4 7% 5% 4 4 4 5% 6% 33%	2453
	11th to 20th	Night	17% 11% 4 8% 5% 5% 5% 3 5% 6% 30%	2569
	21st to end	Night	19% 15% 4 9% 5% 4 3 3 4 5% 28%	2660
December	1st to 10th	Night	18% 16% 5% 11% 5% 5% 4 3 5% 6% 20%	2660
	11th to 20th	Night	20% 14% 4 10% 6% 5% 4 3 4 5% 25%	3288
	21st to end	Night	20% 17% 6% 11% 5% 4 3 3 4 5% 22%	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	60% 5% 12% 17% 6% 1	2518
	11th to 20th	Day	61% 5% 9% 17% 9% 1	2520
	21st to end	Day	59% 5% 9% 18% 8% 1	2772
February	1st to 10th	Day	61% 3 6% 18% 10% 2	1629
	11th to 20th	Day	58% 4 11% 14% 12% 1	1761
	21st to end	Day	61% 4 7% 16% 9% 3	1570
March	1st to 10th	Day	61% 5% 7% 14% 11% 2	3119
	11th to 20th	Day	59% 5% 10% 12% 11% 4	3273
	21st to end	Day	47% 3 9% 19% 17% 4	4166
April	1st to 10th	Day	57% 5% 8% 16% 12% 3	2280
	11th to 20th	Day	51% 4 9% 21% 12% 3	2254
	21st to end	Day	55% 6% 7% 16% 13% 3	2460
May	1st to 10th	Day	51% 6% 10% 18% 13% 1	4424
	11th to 20th	Day	46% 8% 17% 19% 9% 1	4402
	21st to end	Day	49% 7% 10% 18% 15% 1	4837
June	1st to 10th	Day	54% 8% 9% 18% 10% 1	2660
	11th to 20th	Day	46% 8% 12% 20% 11% 2	2660
	21st to end	Day	58% 7% 10% 16% 9%	2660
July	1st to 10th	Day	46% 8% 13% 23% 8%	4370
	11th to 20th	Day	44% 8% 17% 24% 7%	4365
	21st to end	Day	40% 8% 14% 27% 11%	4661
August	1st to 10th	Day	47% 8% 16% 22% 7%	4409
	11th to 20th	Day	45% 10% 16% 24% 5%	4131
	21st to end	Day	44% 7% 13% 21% 14% 1	4180
September	1st to 10th	Day	40% 6% 16% 26% 12% 1	2280
	11th to 20th	Day	38% 7% 13% 29% 11% 1	2195
	21st to end	Day	45% 5% 12% 26% 11%	2090
October	1st to 10th	Day	48% 6% 13% 26% 7% 1	3264
	11th to 20th	Day	48% 7% 13% 25% 7% 1	3027
	21st to end	Day	45% 5% 21% 19% 9% 1	3081
November	1st to 10th	Day	51% 6% 13% 19% 10% 1	1698
	11th to 20th	Day	57% 5% 10% 16% 11% 1	1608
	21st to end	Day	60% 6% 11% 16% 7% 1	1520
December	1st to 10th	Day	65% 4 9% 15% 7%	1520
	11th to 20th	Day	60% 4 8% 18% 9%	1906
	21st to end	Day	64% 5% 7% 14% 10%	2772
January	1st to 10th	Night	58% 6% 13% 16% 7%	4429
	11th to 20th	Night	57% 5% 11% 20% 5% 1	4440
	21st to end	Night	60% 6% 10% 14% 9% 1	4884
February	1st to 10th	Night	57% 5% 9% 19% 10% 1	2546
	11th to 20th	Night	55% 5% 9% 18% 12% 1	2316
	21st to end	Night	52% 5% 8% 18% 14% 2	1884
March	1st to 10th	Night	57% 6% 11% 13% 10% 3	3734
	11th to 20th	Night	59% 5% 7% 14% 13% 2	3672
	21st to end	Night	49% 4 9% 21% 13% 4	3466
April	1st to 10th	Night	54% 5% 8% 16% 15% 2	1900
	11th to 20th	Night	46% 6% 9% 23% 14% 3	1875
	21st to end	Night	50% 4 8% 21% 15% 2	1720
May	1st to 10th	Night	51% 7% 13% 17% 9% 2	2566
	11th to 20th	Night	44% 8% 14% 21% 11% 2	2496
	21st to end	Night	48% 7% 12% 17% 14% 1	2739
June	1st to 10th	Night	46% 7% 12% 22% 12% 1	1520
	11th to 20th	Night	45% 7% 12% 20% 12% 3	1520
	21st to end	Night	48% 8% 12% 18% 13%	1520
July	1st to 10th	Night	45% 6% 20% 19% 9% 1	2480
	11th to 20th	Night	40% 7% 19% 27% 6%	2472
	21st to end	Night	33% 7% 19% 29% 12%	2651
August	1st to 10th	Night	42% 7% 17% 26% 8%	2496
	11th to 20th	Night	41% 6% 21% 25% 7%	2729
	21st to end	Night	43% 6% 15% 24% 12%	3476
September	1st to 10th	Night	35% 6% 16% 28% 14% 1	1900
	11th to 20th	Night	35% 4 17% 32% 11% 1	1984
	21st to end	Night	40% 6% 11% 30% 13%	2090
October	1st to 10th	Night	46% 5% 13% 26% 10%	3694
	11th to 20th	Night	42% 6% 12% 31% 9%	3891
	21st to end	Night	46% 4 17% 19% 12% 2	4467
November	1st to 10th	Night	50% 5% 13% 22% 9% 1	2453
	11th to 20th	Night	52% 6% 12% 19% 10% 1	2569
	21st to end	Night	58% 5% 10% 17% 9% 1	2660
December	1st to 10th	Night	63% 5% 11% 16% 6%	2660
	11th to 20th	Night	61% 4 7% 17% 10% 1	3288
	21st to end	Night	64% 5% 6% 17% 7% 1	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	24% 19% 39% 14% 4	180
	11th to 20th	Day	27% 17% 39% 12% 5% 1	180
	21st to end	Day	15% 23% 43% 15% 3 1	198
February	1st to 10th	Day	33% 26% 32% 7% 2	231
	11th to 20th	Day	23% 31% 35% 11% 1	359
	21st to end	Day	27% 26% 31% 13% 3	382
March	1st to 10th	Day	24% 23% 33% 16% 3	460
	11th to 20th	Day	26% 26% 33% 12% 3	460
	21st to end	Day	29% 26% 25% 12% 6% 1	506
April	1st to 10th	Day	30% 20% 30% 14% 6%	460
	11th to 20th	Day	35% 19% 25% 12% 8% 1	452
	21st to end	Day	32% 21% 32% 9% 5% 1	460
May	1st to 10th	Day	30% 19% 34% 13% 3 2	463
	11th to 20th	Day	23% 20% 32% 18% 5% 1	487
	21st to end	Day	24% 22% 34% 15% 4 1	529
June	1st to 10th	Day	23% 16% 41% 13% 6%	490
	11th to 20th	Day	21% 20% 31% 17% 10% 1	490
	21st to end	Day	29% 14% 32% 18% 7% 1	490
July	1st to 10th	Day	15% 12% 40% 25% 7% 2	485
	11th to 20th	Day	16% 14% 37% 27% 5% 1	484
	21st to end	Day	15% 10% 35% 29% 10% 2	532
August	1st to 10th	Day	16% 12% 34% 25% 10% 2	486
	11th to 20th	Day	16% 10% 32% 25% 12% 5%	479
	21st to end	Day	17% 18% 27% 20% 14% 4	539
September	1st to 10th	Day	19% 12% 33% 21% 10% 4	490
	11th to 20th	Day	16% 11% 30% 24% 13% 6%	490
	21st to end	Day	22% 17% 28% 18% 11% 4	490
October	1st to 10th	Day	27% 17% 24% 20% 9% 2	490
	11th to 20th	Day	27% 22% 27% 16% 7% 1	456
	21st to end	Day	32% 19% 29% 16% 3	429
November	1st to 10th	Day	28% 20% 29% 18% 5% 1	374
	11th to 20th	Day	28% 19% 34% 15% 3	268
	21st to end	Day	28% 29% 30% 11% 2 1	180
December	1st to 10th	Day	31% 18% 31% 13% 7% 1	180
	11th to 20th	Day	30% 28% 29% 10% 3	180
	21st to end	Day	33% 23% 28% 11% 5% 1	198
January	1st to 10th	Night	25% 16% 37% 18% 4	760
	11th to 20th	Night	21% 20% 34% 20% 5%	760
	21st to end	Night	15% 18% 38% 23% 5%	836
February	1st to 10th	Night	17% 21% 36% 21% 5%	760
	11th to 20th	Night	19% 22% 36% 19% 3 1	743
	21st to end	Night	21% 20% 33% 22% 3	628
March	1st to 10th	Night	26% 17% 33% 21% 4	760
	11th to 20th	Night	25% 24% 29% 16% 5% 1	760
	21st to end	Night	22% 18% 31% 23% 5% 1	836
April	1st to 10th	Night	29% 16% 28% 22% 5%	760
	11th to 20th	Night	24% 17% 31% 21% 6%	751
	21st to end	Night	27% 19% 29% 19% 5% 1	580
May	1st to 10th	Night	26% 15% 30% 21% 7% 1	413
	11th to 20th	Night	23% 12% 31% 26% 7%	374
	21st to end	Night	20% 12% 40% 20% 7%	411
June	1st to 10th	Night	22% 10% 33% 27% 7%	380
	11th to 20th	Night	19% 11% 27% 31% 10% 1	380
	21st to end	Night	22% 7% 29% 31% 10% 1	380
July	1st to 10th	Night	14% 6% 34% 35% 11% 1	370
	11th to 20th	Night	14% 5% 28% 39% 13% 1	368
	21st to end	Night	13% 7% 28% 38% 14%	416
August	1st to 10th	Night	11% 5% 23% 43% 17% 1	378
	11th to 20th	Night	15% 5% 24% 34% 19% 2	507
	21st to end	Night	16% 10% 28% 29% 15% 2	836
September	1st to 10th	Night	15% 10% 30% 34% 11% 1	760
	11th to 20th	Night	18% 8% 28% 27% 18% 2	760
	21st to end	Night	22% 10% 29% 23% 14% 2	760
October	1st to 10th	Night	21% 15% 28% 24% 10% 1	760
	11th to 20th	Night	28% 14% 29% 22% 8%	760
	21st to end	Night	28% 17% 29% 21% 5%	836
November	1st to 10th	Night	23% 19% 27% 23% 6% 1	755
	11th to 20th	Night	25% 17% 30% 19% 8% 1	760
	21st to end	Night	28% 21% 25% 20% 5% 1	760
December	1st to 10th	Night	27% 17% 29% 21% 4	760
	11th to 20th	Night	28% 18% 33% 16% 5% 1	760
	21st to end	Night	31% 19% 28% 18% 3	836

Page generated at 2024-11-01 22:47:42. Version ac07

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