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 2024-01-22.

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	18% 13% 5% 9% 7% 3 5% 4 5% 6% 26%	74615
	Night	17% 13% 5% 9% 7% 4 5% 4 4 5% 26%	75291
Transparency	Day	58% 7% 10% 16% 8% 1	74320
	Night	58% 7% 10% 16% 8% 1	75121
Seeing	Day	27% 21% 28% 16% 7% 2	14131
	Night	24% 19% 26% 22% 8% 1	22870

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	14% 16% 9% 15% 11% 5% 5% 4 4 4 12%	1517
	11th to 20th	Day	14% 17% 8% 14% 12% 4 4 4 3 4 17%	1520
	21st to end	Day	8% 13% 7% 15% 11% 4 7% 4 5% 5% 21%	1592
February	1st to 10th	Day	12% 16% 7% 14% 12% 6% 6% 3 3 4 16%	1500
	11th to 20th	Day	12% 18% 9% 15% 8% 4 6% 4 4 4 16%	1734
	21st to end	Day	10% 19% 5% 13% 9% 5% 7% 4 5% 4 20%	1480
March	1st to 10th	Day	14% 15% 7% 11% 9% 4 5% 4 4 5% 23%	1797
	11th to 20th	Day	15% 14% 8% 8% 8% 3 4 3 4 4 27%	1912
	21st to end	Day	16% 16% 6% 12% 7% 3 3 3 4 4 26%	2272
April	1st to 10th	Day	20% 16% 6% 9% 7% 2 3 3 4 4 23%	2160
	11th to 20th	Day	18% 15% 4 7% 5% 2 4 4 4 5% 33%	2226
	21st to end	Day	23% 15% 5% 7% 5% 3 3 4 4 5% 27%	2340
May	1st to 10th	Day	22% 13% 4 6% 5% 3 4 4 4 5% 30%	2340
	11th to 20th	Day	21% 10% 4 5% 6% 4 4 3 5% 7% 30%	2446
	21st to end	Day	19% 9% 3 7% 6% 4 5% 6% 6% 9% 26%	2725
June	1st to 10th	Day	28% 9% 3 5% 6% 3 4 5% 6% 7% 22%	2668
	11th to 20th	Day	20% 7% 3 6% 6% 4 5% 6% 6% 8% 30%	2700
	21st to end	Day	23% 9% 4 7% 6% 4 6% 5% 6% 6% 23%	2665
July	1st to 10th	Day	18% 8% 3 6% 6% 4 6% 5% 6% 8% 30%	2520
	11th to 20th	Day	17% 8% 3 7% 6% 4 6% 6% 6% 8% 29%	2520
	21st to end	Day	20% 8% 3 7% 6% 4 6% 6% 6% 8% 26%	2744
August	1st to 10th	Day	20% 7% 3 7% 6% 5% 5% 5% 7% 9% 26%	2431
	11th to 20th	Day	17% 7% 3 8% 7% 3 5% 5% 6% 7% 30%	2304
	21st to end	Day	18% 7% 3 7% 6% 3 5% 4 6% 7% 34%	2476
September	1st to 10th	Day	19% 7% 3 5% 5% 4 4 5% 6% 7% 36%	2152
	11th to 20th	Day	19% 9% 3 5% 4 2 3 4 4 7% 41%	1980
	21st to end	Day	19% 8% 3 6% 5% 3 4 5% 5% 8% 34%	1980
October	1st to 10th	Day	20% 12% 4 6% 5% 2 4 5% 5% 8% 29%	1980
	11th to 20th	Day	17% 15% 5% 9% 7% 3 5% 5% 5% 6% 24%	1681
	21st to end	Day	24% 20% 5% 7% 5% 3 3 4 4 4 20%	1782
November	1st to 10th	Day	17% 19% 6% 8% 6% 3 3 4 3 4 27%	1671
	11th to 20th	Day	17% 15% 9% 12% 6% 3 5% 4 4 6% 21%	1710
	21st to end	Day	16% 16% 8% 13% 7% 3 5% 4 4 5% 18%	1492
December	1st to 10th	Day	18% 20% 12% 13% 7% 3 4 3 3 3 15%	1330
	11th to 20th	Day	18% 17% 8% 11% 7% 3 5% 3 3 4 20%	1668
	21st to end	Day	20% 21% 7% 12% 9% 3 4 4 2 3 16%	2600
January	1st to 10th	Night	12% 19% 10% 14% 12% 4 6% 4 4 4 12%	2649
	11th to 20th	Night	12% 17% 9% 14% 11% 5% 7% 5% 4 3 13%	2660
	21st to end	Night	9% 13% 7% 14% 11% 6% 8% 6% 5% 4 18%	2798
February	1st to 10th	Night	11% 15% 7% 13% 12% 5% 7% 4 4 4 18%	2458
	11th to 20th	Night	10% 17% 8% 16% 9% 5% 5% 4 3 5% 18%	2107
	21st to end	Night	11% 15% 7% 12% 8% 4 7% 4 3 4 23%	1776
March	1st to 10th	Night	13% 17% 8% 11% 7% 4 5% 3 4 5% 24%	2150
	11th to 20th	Night	14% 15% 5% 11% 6% 3 5% 4 4 5% 27%	2047
	21st to end	Night	16% 15% 6% 9% 5% 3 3 4 4 4 29%	2081
April	1st to 10th	Night	20% 16% 6% 7% 6% 3 4 4 4 5% 26%	1800
	11th to 20th	Night	18% 12% 4 5% 6% 3 5% 6% 4 6% 33%	1682
	21st to end	Night	21% 14% 4 6% 6% 2 4 5% 5% 5% 28%	1620
May	1st to 10th	Night	21% 11% 4 7% 5% 3 3 5% 5% 7% 29%	1620
	11th to 20th	Night	18% 10% 4 7% 6% 4 4 4 5% 6% 32%	1461
	21st to end	Night	20% 8% 4 5% 6% 2 4 4 7% 9% 32%	1550
June	1st to 10th	Night	27% 9% 3 6% 5% 3 4 4 5% 7% 27%	1288
	11th to 20th	Night	19% 8% 2 6% 5% 2 5% 5% 6% 8% 34%	1260
	21st to end	Night	19% 7% 4 8% 6% 3 5% 4 6% 6% 32%	1288
July	1st to 10th	Night	16% 7% 3 6% 5% 4 5% 5% 6% 8% 35%	1440
	11th to 20th	Night	14% 7% 2 6% 6% 4 6% 8% 8% 8% 33%	1440
	21st to end	Night	15% 8% 3 6% 6% 4 5% 6% 6% 7% 34%	1574
August	1st to 10th	Night	16% 5% 2 5% 5% 3 4 5% 5% 9% 39%	1488
	11th to 20th	Night	15% 8% 2 5% 6% 3 5% 5% 6% 8% 37%	1596
	21st to end	Night	15% 7% 3 6% 5% 3 5% 4 6% 6% 41%	1877
September	1st to 10th	Night	15% 8% 3 6% 4 3 4 5% 5% 7% 40%	1808
	11th to 20th	Night	17% 8% 2 5% 3 2 4 4 5% 6% 43%	1980
	21st to end	Night	19% 9% 2 5% 4 3 3 4 4 8% 41%	1980
October	1st to 10th	Night	20% 9% 3 6% 5% 3 4 5% 4 7% 35%	1980
	11th to 20th	Night	21% 13% 4 6% 6% 4 4 4 4 5% 28%	2274
	21st to end	Night	23% 18% 4 7% 5% 3 4 5% 4 4 24%	2574
November	1st to 10th	Night	19% 16% 5% 7% 5% 3 5% 4 4 5% 26%	2407
	11th to 20th	Night	17% 13% 7% 11% 6% 3 3 4 4 5% 25%	2470
	21st to end	Night	15% 16% 8% 12% 9% 3 4 3 3 4 21%	2683
December	1st to 10th	Night	18% 19% 8% 13% 8% 4 4 4 4 4 12%	2850
	11th to 20th	Night	16% 18% 8% 15% 9% 4 5% 4 4 3 13%	3531
	21st to end	Night	21% 18% 8% 9% 7% 3 3 4 3 3 21%	5044

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	73% 6% 7% 10% 4	1518
	11th to 20th	Day	68% 7% 6% 12% 6% 1	1520
	21st to end	Day	60% 9% 7% 13% 10% 1	1592
February	1st to 10th	Day	71% 6% 6% 9% 8% 1	1500
	11th to 20th	Day	70% 6% 7% 9% 6% 1	1743
	21st to end	Day	65% 6% 7% 12% 8% 2	1480
March	1st to 10th	Day	62% 6% 8% 14% 7% 2	1800
	11th to 20th	Day	59% 6% 8% 13% 11% 2	1912
	21st to end	Day	62% 5% 6% 14% 9% 2	2272
April	1st to 10th	Day	65% 4 8% 12% 8% 3	2160
	11th to 20th	Day	54% 5% 8% 19% 12% 1	2226
	21st to end	Day	60% 5% 8% 14% 9% 3	2340
May	1st to 10th	Day	58% 4 8% 17% 12% 2	2340
	11th to 20th	Day	55% 6% 11% 17% 10% 1	2450
	21st to end	Day	54% 8% 11% 17% 9% 1	2725
June	1st to 10th	Day	61% 6% 9% 18% 5%	2668
	11th to 20th	Day	50% 8% 11% 20% 9% 1	2700
	21st to end	Day	59% 8% 10% 17% 6%	2665
July	1st to 10th	Day	49% 9% 14% 21% 7%	2450
	11th to 20th	Day	50% 9% 13% 21% 7%	2445
	21st to end	Day	54% 8% 13% 18% 5% 1	2591
August	1st to 10th	Day	52% 8% 16% 20% 4	2417
	11th to 20th	Day	50% 9% 15% 17% 8%	2304
	21st to end	Day	48% 8% 13% 21% 10%	2476
September	1st to 10th	Day	45% 8% 14% 22% 11%	2152
	11th to 20th	Day	43% 5% 11% 27% 13% 1	1980
	21st to end	Day	47% 7% 12% 23% 11% 1	1980
October	1st to 10th	Day	51% 6% 12% 21% 10%	1980
	11th to 20th	Day	57% 8% 13% 17% 5%	1681
	21st to end	Day	67% 4 9% 12% 7% 1	1782
November	1st to 10th	Day	59% 5% 11% 16% 8% 1	1671
	11th to 20th	Day	64% 6% 9% 13% 7% 1	1710
	21st to end	Day	64% 8% 10% 14% 3	1492
December	1st to 10th	Day	73% 6% 6% 9% 5%	1330
	11th to 20th	Day	65% 6% 5% 12% 11% 1	1668
	21st to end	Day	71% 6% 6% 11% 6% 1	2600
January	1st to 10th	Night	72% 7% 7% 9% 4	2649
	11th to 20th	Night	72% 8% 7% 9% 4 1	2660
	21st to end	Night	62% 9% 9% 12% 6% 2	2798
February	1st to 10th	Night	66% 8% 8% 12% 6% 1	2458
	11th to 20th	Night	68% 6% 8% 11% 6% 1	2109
	21st to end	Night	63% 6% 6% 14% 10% 1	1776
March	1st to 10th	Night	64% 5% 6% 16% 8% 1	2160
	11th to 20th	Night	59% 6% 10% 12% 11% 2	2048
	21st to end	Night	57% 6% 8% 18% 8% 3	2081
April	1st to 10th	Night	61% 4 8% 13% 12% 2	1800
	11th to 20th	Night	50% 7% 10% 19% 12% 1	1682
	21st to end	Night	58% 6% 10% 15% 9% 3	1620
May	1st to 10th	Night	54% 6% 10% 18% 12% 1	1620
	11th to 20th	Night	54% 5% 11% 19% 10% 1	1462
	21st to end	Night	49% 7% 13% 20% 9% 1	1551
June	1st to 10th	Night	56% 7% 12% 19% 7%	1288
	11th to 20th	Night	48% 6% 12% 21% 11% 1	1260
	21st to end	Night	52% 7% 13% 21% 7%	1288
July	1st to 10th	Night	46% 8% 16% 21% 9%	1400
	11th to 20th	Night	42% 11% 15% 25% 7%	1392
	21st to end	Night	47% 9% 15% 20% 8%	1486
August	1st to 10th	Night	41% 9% 21% 25% 4	1478
	11th to 20th	Night	43% 10% 18% 23% 6% 1	1596
	21st to end	Night	41% 7% 15% 26% 10%	1877
September	1st to 10th	Night	40% 8% 16% 26% 10%	1808
	11th to 20th	Night	42% 5% 14% 27% 11% 1	1980
	21st to end	Night	42% 7% 14% 24% 11% 1	1980
October	1st to 10th	Night	49% 7% 11% 21% 11% 1	1980
	11th to 20th	Night	56% 8% 13% 18% 6%	2274
	21st to end	Night	63% 6% 9% 14% 8%	2574
November	1st to 10th	Night	61% 5% 11% 15% 8% 1	2407
	11th to 20th	Night	60% 5% 10% 14% 9% 1	2470
	21st to end	Night	66% 6% 11% 12% 4	2683
December	1st to 10th	Night	73% 6% 8% 9% 3	2850
	11th to 20th	Night	71% 7% 6% 9% 6%	3532
	21st to end	Night	68% 7% 7% 13% 6%	5044

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% 28% 32% 10%	180
	11th to 20th	Day	31% 31% 24% 12% 2 1	180
	21st to end	Day	23% 24% 39% 13% 1 1	178
February	1st to 10th	Day	33% 29% 25% 12% 1	220
	11th to 20th	Day	31% 32% 27% 9% 1	410
	21st to end	Day	32% 29% 24% 14% 2	346
March	1st to 10th	Day	27% 28% 30% 12% 4	420
	11th to 20th	Day	31% 27% 25% 13% 3 1	420
	21st to end	Day	30% 24% 24% 14% 8% 1	462
April	1st to 10th	Day	38% 21% 23% 11% 6% 1	420
	11th to 20th	Day	32% 26% 22% 12% 5% 2	412
	21st to end	Day	36% 22% 28% 9% 3 2	420
May	1st to 10th	Day	36% 18% 30% 10% 4 2	423
	11th to 20th	Day	28% 22% 30% 14% 5% 1	447
	21st to end	Day	21% 25% 33% 15% 5% 1	485
June	1st to 10th	Day	32% 18% 29% 14% 6% 1	598
	11th to 20th	Day	23% 17% 27% 21% 11% 2	630
	21st to end	Day	24% 14% 31% 21% 9% 1	595
July	1st to 10th	Day	20% 16% 34% 21% 8% 1	445
	11th to 20th	Day	19% 14% 38% 18% 10% 1	444
	21st to end	Day	17% 16% 35% 23% 8% 1	488
August	1st to 10th	Day	18% 17% 31% 23% 10% 1	446
	11th to 20th	Day	18% 16% 27% 24% 11% 4	439
	21st to end	Day	21% 20% 24% 20% 12% 4	495
September	1st to 10th	Day	19% 17% 27% 21% 11% 4	450
	11th to 20th	Day	23% 14% 26% 19% 11% 7%	450
	21st to end	Day	20% 16% 28% 19% 12% 6%	450
October	1st to 10th	Day	24% 18% 24% 18% 11% 4	450
	11th to 20th	Day	26% 25% 22% 17% 8% 2	367
	21st to end	Day	34% 23% 22% 16% 5%	396
November	1st to 10th	Day	31% 22% 24% 18% 4	365
	11th to 20th	Day	28% 24% 26% 14% 6% 1	370
	21st to end	Day	31% 24% 27% 14% 3 1	272
December	1st to 10th	Day	28% 26% 29% 13% 3	180
	11th to 20th	Day	35% 28% 28% 6% 3 1	180
	21st to end	Day	38% 28% 23% 7% 3 1	198
January	1st to 10th	Night	25% 27% 31% 15% 3	760
	11th to 20th	Night	24% 28% 28% 17% 3	760
	21st to end	Night	17% 28% 33% 19% 4 1	800
February	1st to 10th	Night	23% 26% 32% 16% 3	720
	11th to 20th	Night	23% 30% 29% 16% 2	703
	21st to end	Night	25% 24% 33% 15% 3	592
March	1st to 10th	Night	25% 21% 32% 19% 3	720
	11th to 20th	Night	26% 25% 25% 18% 5% 1	720
	21st to end	Night	25% 22% 23% 22% 6% 1	792
April	1st to 10th	Night	30% 22% 26% 17% 5%	720
	11th to 20th	Night	25% 19% 24% 24% 7%	618
	21st to end	Night	32% 19% 24% 19% 6% 1	540
May	1st to 10th	Night	26% 16% 26% 24% 7% 1	540
	11th to 20th	Night	23% 15% 30% 28% 4 1	400
	21st to end	Night	23% 12% 28% 27% 9% 1	389
June	1st to 10th	Night	28% 11% 25% 28% 7%	360
	11th to 20th	Night	21% 13% 19% 30% 16% 1	360
	21st to end	Night	20% 8% 28% 34% 11%	360
July	1st to 10th	Night	17% 9% 28% 31% 14% 1	350
	11th to 20th	Night	17% 6% 26% 35% 14% 2	348
	21st to end	Night	17% 8% 21% 38% 16%	394
August	1st to 10th	Night	17% 5% 22% 36% 19% 1	414
	11th to 20th	Night	15% 9% 24% 34% 17% 1	532
	21st to end	Night	17% 9% 25% 30% 16% 2	689
September	1st to 10th	Night	16% 9% 27% 32% 15% 1	720
	11th to 20th	Night	22% 10% 20% 27% 19% 2	720
	21st to end	Night	21% 13% 24% 25% 15% 2	720
October	1st to 10th	Night	24% 12% 22% 29% 12% 1	720
	11th to 20th	Night	27% 18% 23% 20% 10% 2	720
	21st to end	Night	31% 21% 24% 19% 4	792
November	1st to 10th	Night	29% 20% 23% 22% 6%	740
	11th to 20th	Night	24% 24% 25% 17% 8% 2	760
	21st to end	Night	26% 23% 26% 19% 5% 1	816
December	1st to 10th	Night	29% 24% 28% 14% 4	850
	11th to 20th	Night	31% 24% 22% 17% 5%	850
	21st to end	Night	33% 25% 26% 13% 3	881

Page generated at 2024-01-19 09:28:30. Version ac07

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