Ruisseau d'or
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Ruisseau d'or clear sky chart from 2005-11-06 to 2025-01-22.

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% 13% 4 10% 6% 5% 5% 4 5% 6% 25%	104632
	Night	16% 15% 5% 11% 6% 5% 4 3 4 5% 25%	104750
Transparency	Day	56% 7% 11% 17% 8% 1	108118
	Night	58% 7% 11% 16% 7% 1	109354
Seeing	Day	27% 21% 28% 16% 7% 2	15423
	Night	24% 19% 26% 22% 8% 1	24144

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% 17% 8% 17% 11% 7% 5% 3 5% 5% 11%	2597
	11th to 20th	Day	9% 15% 7% 23% 14% 6% 2 2 2 3 16%	2600
	21st to end	Day	9% 17% 7% 19% 7% 7% 5% 3 4 4 18%	2780
February	1st to 10th	Day	12% 16% 6% 16% 10% 7% 5% 3 3 3 18%	1583
	11th to 20th	Day	11% 20% 9% 16% 8% 6% 6% 3 4 3 16%	1833
	21st to end	Day	9% 20% 4 14% 9% 7% 5% 3 5% 4 20%	1570
March	1st to 10th	Day	20% 17% 5% 9% 7% 5% 4 3 4 5% 24%	3116
	11th to 20th	Day	16% 24% 7% 15% 5% 4 3 2 3 3 19%	3370
	21st to end	Day	17% 17% 6% 12% 5% 4 2 2 4 4 28%	3992
April	1st to 10th	Day	20% 19% 4 10% 6% 3 3 3 4 5% 23%	2280
	11th to 20th	Day	17% 17% 4 8% 4 3 3 3 4 5% 32%	2352
	21st to end	Day	23% 15% 4 8% 3 4 3 2 4 5% 28%	2470
May	1st to 10th	Day	22% 11% 4 9% 7% 5% 4 4 4 5% 25%	4106
	11th to 20th	Day	21% 10% 3 8% 6% 6% 5% 3 5% 7% 26%	4352
	21st to end	Day	15% 8% 3 8% 6% 6% 6% 4 7% 9% 28%	4837
June	1st to 10th	Day	27% 10% 3 6% 5% 5% 4 4 6% 7% 23%	2817
	11th to 20th	Day	19% 8% 3 7% 5% 5% 5% 5% 6% 8% 30%	2850
	21st to end	Day	23% 11% 4 8% 6% 6% 5% 4 6% 6% 23%	2813
July	1st to 10th	Day	15% 8% 3 8% 6% 6% 6% 5% 7% 8% 29%	4440
	11th to 20th	Day	15% 7% 3 8% 6% 6% 5% 5% 7% 8% 29%	4440
	21st to end	Day	15% 8% 3 7% 5% 5% 5% 4 6% 6% 36%	4814
August	1st to 10th	Day	19% 8% 3 9% 5% 6% 6% 5% 7% 8% 24%	4279
	11th to 20th	Day	18% 9% 3 10% 6% 5% 6% 4 6% 8% 24%	4045
	21st to end	Day	20% 7% 3 7% 5% 4 4 3 6% 7% 34%	4350
September	1st to 10th	Day	18% 7% 2 6% 4 5% 4 4 6% 6% 37%	2271
	11th to 20th	Day	18% 9% 2 6% 4 3 3 4 4 6% 41%	2090
	21st to end	Day	19% 9% 3 7% 4 4 4 4 6% 8% 33%	2090
October	1st to 10th	Day	19% 13% 3 8% 4 3 4 4 5% 8% 29%	2090
	11th to 20th	Day	16% 16% 4 10% 5% 4 5% 3 5% 5% 25%	1773
	21st to end	Day	22% 20% 5% 9% 4 4 3 3 4 4 21%	1881
November	1st to 10th	Day	16% 19% 5% 9% 5% 4 3 3 4 4 27%	1761
	11th to 20th	Day	16% 17% 7% 12% 6% 4 4 3 4 5% 22%	1800
	21st to end	Day	17% 18% 7% 14% 6% 5% 4 3 4 5% 17%	1569
December	1st to 10th	Day	12% 21% 9% 20% 10% 5% 4 2 3 3 12%	2280
	11th to 20th	Day	15% 18% 7% 13% 6% 4 5% 3 3 5% 22%	2618
	21st to end	Day	15% 21% 6% 14% 5% 4 5% 3 3 5% 18%	3723
January	1st to 10th	Night	12% 18% 8% 20% 11% 6% 4 3 4 3 11%	4569
	11th to 20th	Night	10% 18% 7% 18% 14% 8% 6% 3 3 3 11%	4580
	21st to end	Night	10% 16% 9% 17% 8% 8% 5% 4 4 4 15%	4899
February	1st to 10th	Night	11% 16% 6% 15% 10% 7% 5% 3 4 4 19%	2595
	11th to 20th	Night	10% 18% 7% 18% 8% 7% 4 3 3 5% 17%	2228
	21st to end	Night	11% 16% 7% 13% 7% 6% 6% 4 3 5% 24%	1884
March	1st to 10th	Night	19% 20% 5% 9% 5% 4 5% 2 3 4 24%	3724
	11th to 20th	Night	12% 21% 8% 15% 6% 4 4 2 3 4 21%	3589
	21st to end	Night	20% 18% 4 11% 5% 3 2 3 4 4 26%	3637
April	1st to 10th	Night	19% 17% 5% 8% 4 3 3 3 4 4 28%	1900
	11th to 20th	Night	18% 13% 4 6% 5% 4 4 5% 4 6% 31%	1776
	21st to end	Night	20% 15% 4 7% 5% 3 5% 3 5% 5% 29%	1710
May	1st to 10th	Night	23% 11% 3 7% 4 4 5% 4 6% 6% 26%	2834
	11th to 20th	Night	18% 11% 3 8% 5% 5% 4 3 5% 6% 32%	2569
	21st to end	Night	18% 7% 2 5% 5% 3 4 4 7% 9% 34%	2738
June	1st to 10th	Night	26% 11% 2 7% 4 4 4 3 5% 7% 27%	1359
	11th to 20th	Night	18% 9% 2 7% 4 4 4 5% 6% 8% 34%	1330
	21st to end	Night	19% 9% 3 9% 5% 4 5% 4 6% 6% 31%	1360
July	1st to 10th	Night	15% 8% 3 9% 6% 6% 5% 4 6% 7% 32%	2520
	11th to 20th	Night	18% 8% 2 7% 5% 5% 5% 5% 6% 6% 32%	2520
	21st to end	Night	14% 8% 2 7% 4 4 5% 4 6% 7% 39%	2739
August	1st to 10th	Night	21% 8% 3 9% 5% 4 5% 4 5% 7% 31%	2618
	11th to 20th	Night	15% 8% 3 8% 6% 7% 6% 5% 7% 7% 30%	2782
	21st to end	Night	18% 8% 2 6% 4 5% 4 3 5% 6% 39%	3303
September	1st to 10th	Night	15% 9% 2 6% 3 4 4 4 5% 7% 40%	1909
	11th to 20th	Night	16% 8% 2 6% 3 3 3 4 5% 6% 44%	2090
	21st to end	Night	18% 9% 2 6% 4 4 3 3 4 8% 40%	2090
October	1st to 10th	Night	19% 9% 3 6% 5% 4 4 3 5% 7% 35%	2090
	11th to 20th	Night	20% 14% 4 7% 5% 4 4 3 4 5% 29%	2402
	21st to end	Night	22% 17% 4 8% 4 4 4 4 4 4 25%	2717
November	1st to 10th	Night	18% 18% 5% 9% 4 4 4 3 5% 5% 25%	2537
	11th to 20th	Night	16% 15% 6% 12% 6% 4 3 3 4 5% 25%	2600
	21st to end	Night	16% 18% 7% 14% 7% 4 4 3 4 4 20%	2825
December	1st to 10th	Night	13% 20% 10% 22% 10% 5% 3 3 3 3 9%	4910
	11th to 20th	Night	14% 20% 6% 16% 9% 5% 4 3 4 4 15%	5591
	21st to end	Night	16% 19% 7% 10% 6% 4 4 3 3 4 24%	7226

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% 9% 8% 10% 3	2598
	11th to 20th	Day	71% 7% 4 12% 5% 1	2600
	21st to end	Day	65% 8% 8% 8% 9% 2	2780
February	1st to 10th	Day	69% 6% 6% 10% 8% 1	1583
	11th to 20th	Day	70% 6% 7% 10% 6% 1	1842
	21st to end	Day	64% 6% 7% 13% 7% 2	1570
March	1st to 10th	Day	63% 6% 8% 11% 10% 2	3119
	11th to 20th	Day	68% 6% 8% 10% 7% 1	3370
	21st to end	Day	58% 6% 6% 14% 13% 2	3992
April	1st to 10th	Day	64% 4 8% 13% 8% 2	2280
	11th to 20th	Day	55% 5% 8% 20% 12% 1	2352
	21st to end	Day	59% 5% 8% 15% 10% 3	2470
May	1st to 10th	Day	58% 8% 10% 16% 8% 1	4120
	11th to 20th	Day	56% 9% 14% 14% 6% 1	4356
	21st to end	Day	48% 10% 12% 20% 10%	4837
June	1st to 10th	Day	60% 7% 9% 19% 5%	2817
	11th to 20th	Day	49% 8% 12% 20% 9% 1	2850
	21st to end	Day	58% 8% 10% 17% 6%	2813
July	1st to 10th	Day	46% 9% 16% 21% 7%	4370
	11th to 20th	Day	46% 10% 15% 25% 4	4365
	21st to end	Day	47% 7% 13% 27% 6%	4661
August	1st to 10th	Day	52% 9% 16% 19% 4	4265
	11th to 20th	Day	53% 10% 16% 16% 5%	4084
	21st to end	Day	46% 8% 14% 19% 11% 2	4350
September	1st to 10th	Day	43% 8% 15% 23% 11%	2271
	11th to 20th	Day	42% 6% 11% 27% 13% 1	2090
	21st to end	Day	47% 7% 12% 22% 10% 1	2090
October	1st to 10th	Day	51% 8% 13% 20% 7%	3480
	11th to 20th	Day	53% 6% 11% 22% 7%	2911
	21st to end	Day	52% 5% 15% 18% 10%	3081
November	1st to 10th	Day	59% 6% 10% 16% 8% 1	1761
	11th to 20th	Day	63% 6% 9% 14% 7% 1	1800
	21st to end	Day	65% 8% 10% 14% 3	1569
December	1st to 10th	Day	75% 6% 7% 7% 4	2280
	11th to 20th	Day	60% 7% 9% 11% 12% 1	2618
	21st to end	Day	65% 6% 6% 10% 9% 3	3723
January	1st to 10th	Night	72% 9% 9% 8% 3	4569
	11th to 20th	Night	76% 7% 6% 8% 2	4580
	21st to end	Night	69% 7% 8% 9% 6% 1	4899
February	1st to 10th	Night	65% 8% 8% 12% 7% 1	2595
	11th to 20th	Night	69% 7% 8% 11% 5% 1	2230
	21st to end	Night	62% 6% 6% 15% 9% 2	1884
March	1st to 10th	Night	65% 5% 8% 13% 6% 2	3734
	11th to 20th	Night	66% 7% 9% 10% 7% 1	3590
	21st to end	Night	62% 4 6% 15% 11% 1	3637
April	1st to 10th	Night	60% 4 8% 14% 12% 1	1900
	11th to 20th	Night	51% 7% 10% 18% 12% 1	1776
	21st to end	Night	57% 6% 10% 15% 10% 2	1710
May	1st to 10th	Night	53% 10% 14% 15% 7% 1	2840
	11th to 20th	Night	52% 7% 15% 19% 6% 1	2570
	21st to end	Night	43% 9% 16% 19% 13%	2739
June	1st to 10th	Night	56% 7% 12% 19% 7%	1359
	11th to 20th	Night	48% 7% 13% 21% 11% 1	1330
	21st to end	Night	53% 7% 12% 20% 7%	1360
July	1st to 10th	Night	45% 11% 17% 18% 9%	2480
	11th to 20th	Night	45% 11% 15% 25% 5%	2472
	21st to end	Night	42% 10% 16% 26% 6%	2651
August	1st to 10th	Night	51% 9% 15% 22% 3	2608
	11th to 20th	Night	47% 12% 19% 17% 5%	2809
	21st to end	Night	42% 8% 14% 21% 14% 1	3303
September	1st to 10th	Night	39% 8% 16% 27% 10%	1909
	11th to 20th	Night	41% 5% 14% 27% 12% 1	2090
	21st to end	Night	43% 7% 14% 24% 11% 1	2090
October	1st to 10th	Night	48% 8% 12% 21% 11%	3480
	11th to 20th	Night	51% 8% 10% 22% 8%	4003
	21st to end	Night	51% 7% 14% 19% 8% 2	4467
November	1st to 10th	Night	61% 5% 11% 15% 7% 1	2537
	11th to 20th	Night	60% 5% 10% 14% 9% 1	2600
	21st to end	Night	67% 6% 11% 12% 4	2825
December	1st to 10th	Night	76% 7% 7% 7% 2	4910
	11th to 20th	Night	68% 7% 8% 10% 7%	5592
	21st to end	Night	64% 6% 6% 13% 9% 2	7226

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	31% 30% 30% 9%	200
	11th to 20th	Day	29% 29% 28% 12% 2 1	200
	21st to end	Day	24% 23% 39% 13% 2 1	200
February	1st to 10th	Day	33% 28% 24% 14% 1	243
	11th to 20th	Day	30% 33% 27% 9% 2	449
	21st to end	Day	32% 28% 25% 13% 2	382
March	1st to 10th	Day	28% 27% 30% 12% 4	460
	11th to 20th	Day	32% 27% 25% 12% 3 1	460
	21st to end	Day	33% 23% 24% 13% 7% 1	506
April	1st to 10th	Day	38% 21% 23% 11% 6% 1	460
	11th to 20th	Day	33% 26% 21% 12% 5% 2	452
	21st to end	Day	35% 23% 28% 8% 3 2	460
May	1st to 10th	Day	36% 17% 30% 11% 4 2	463
	11th to 20th	Day	27% 21% 29% 16% 6% 1	487
	21st to end	Day	21% 25% 33% 15% 4 1	529
June	1st to 10th	Day	31% 18% 29% 15% 6% 1	647
	11th to 20th	Day	22% 17% 27% 22% 10% 1	680
	21st to end	Day	26% 14% 30% 20% 9% 1	643
July	1st to 10th	Day	19% 18% 35% 21% 8% 1	485
	11th to 20th	Day	19% 13% 40% 18% 9% 1	484
	21st to end	Day	17% 16% 36% 23% 8% 1	532
August	1st to 10th	Day	18% 16% 33% 22% 10% 1	486
	11th to 20th	Day	18% 17% 27% 24% 10% 4	479
	21st to end	Day	20% 19% 24% 21% 11% 4	539
September	1st to 10th	Day	19% 18% 27% 21% 11% 4	490
	11th to 20th	Day	22% 12% 25% 21% 12% 8%	490
	21st to end	Day	21% 16% 27% 19% 12% 5%	490
October	1st to 10th	Day	24% 18% 25% 18% 11% 4	490
	11th to 20th	Day	27% 24% 23% 16% 8% 2	397
	21st to end	Day	33% 24% 23% 16% 5%	429
November	1st to 10th	Day	33% 21% 24% 17% 4	395
	11th to 20th	Day	28% 25% 27% 13% 6% 1	400
	21st to end	Day	33% 24% 26% 13% 3 1	296
December	1st to 10th	Day	28% 26% 30% 14% 3	200
	11th to 20th	Day	35% 29% 27% 7% 3 1	200
	21st to end	Day	36% 26% 23% 9% 5% 1	220
January	1st to 10th	Night	24% 28% 30% 15% 3	800
	11th to 20th	Night	23% 28% 28% 17% 4	800
	21st to end	Night	17% 28% 32% 19% 4	841
February	1st to 10th	Night	22% 26% 33% 16% 3	760
	11th to 20th	Night	23% 30% 29% 16% 2	743
	21st to end	Night	25% 23% 34% 15% 2	628
March	1st to 10th	Night	26% 20% 31% 19% 3	760
	11th to 20th	Night	26% 25% 25% 18% 5% 1	760
	21st to end	Night	26% 22% 23% 22% 6% 1	836
April	1st to 10th	Night	30% 21% 27% 17% 5%	760
	11th to 20th	Night	26% 19% 24% 24% 7%	652
	21st to end	Night	32% 19% 24% 19% 5% 1	570
May	1st to 10th	Night	26% 15% 26% 24% 7% 1	570
	11th to 20th	Night	22% 14% 29% 29% 6% 1	422
	21st to end	Night	23% 12% 28% 28% 9%	411
June	1st to 10th	Night	28% 12% 24% 28% 7%	380
	11th to 20th	Night	20% 14% 19% 30% 16% 1	380
	21st to end	Night	20% 8% 28% 33% 10%	380
July	1st to 10th	Night	16% 9% 28% 32% 14% 1	370
	11th to 20th	Night	17% 7% 26% 36% 13% 2	368
	21st to end	Night	17% 8% 21% 38% 16%	416
August	1st to 10th	Night	18% 6% 22% 36% 18% 1	438
	11th to 20th	Night	15% 10% 24% 34% 17% 1	562
	21st to end	Night	17% 9% 25% 30% 17% 2	728
September	1st to 10th	Night	16% 10% 27% 31% 15% 1	760
	11th to 20th	Night	21% 10% 19% 27% 20% 2	760
	21st to end	Night	21% 13% 24% 25% 16% 2	760
October	1st to 10th	Night	23% 12% 22% 29% 12% 1	760
	11th to 20th	Night	28% 18% 23% 20% 9% 2	760
	21st to end	Night	30% 22% 25% 19% 4	836
November	1st to 10th	Night	30% 20% 23% 22% 5%	780
	11th to 20th	Night	25% 24% 25% 17% 8% 2	800
	21st to end	Night	27% 23% 26% 18% 4 1	863
December	1st to 10th	Night	29% 24% 28% 15% 4	900
	11th to 20th	Night	32% 24% 22% 17% 5%	900
	21st to end	Night	32% 24% 27% 13% 4	930

Page generated at 2025-01-19 03:06:47. Version ac07

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