Rigaud
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Rigaud clear sky chart from 2005-11-06 to 2024-07-05.

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% 5% 4 6% 7% 32%	89600
	Night	18% 11% 4 8% 5% 4 4 3 5% 6% 31%	89670
Transparency	Day	50% 7% 12% 20% 10% 1	89319
	Night	53% 6% 12% 19% 9% 1	89505
Seeing	Day	21% 14% 29% 22% 10% 3	14076
	Night	22% 12% 29% 27% 9% 1	23117

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	16% 16% 5% 13% 6% 4 4 3 4 5% 22%	2517
	11th to 20th	Day	15% 13% 6% 11% 6% 5% 5% 4 6% 6% 24%	2520
	21st to end	Day	14% 18% 5% 10% 6% 4 5% 5% 6% 6% 22%	2772
February	1st to 10th	Day	14% 16% 4 11% 5% 5% 5% 4 5% 5% 25%	1698
	11th to 20th	Day	14% 13% 4 10% 7% 6% 5% 4 5% 6% 27%	1737
	21st to end	Day	19% 14% 4 9% 6% 5% 4 3 5% 6% 26%	1570
March	1st to 10th	Day	20% 12% 5% 10% 6% 5% 4 3 4 5% 26%	3116
	11th to 20th	Day	12% 17% 5% 11% 7% 4 4 4 5% 5% 26%	3338
	21st to end	Day	15% 8% 3 8% 5% 5% 4 3 5% 5% 39%	4129
April	1st to 10th	Day	21% 11% 3 7% 5% 4 4 3 5% 5% 33%	2280
	11th to 20th	Day	21% 9% 3 7% 5% 4 4 3 5% 5% 35%	2254
	21st to end	Day	22% 9% 3 7% 5% 4 4 4 4 5% 32%	2406
May	1st to 10th	Day	19% 9% 3 9% 5% 5% 5% 4 6% 7% 29%	4419
	11th to 20th	Day	17% 9% 4 8% 5% 5% 4 4 6% 7% 32%	4398
	21st to end	Day	15% 7% 2 7% 5% 5% 5% 4 6% 7% 37%	4837
June	1st to 10th	Day	20% 8% 3 7% 5% 4 5% 4 6% 7% 30%	2660
	11th to 20th	Day	14% 7% 2 7% 5% 5% 5% 4 6% 8% 37%	2660
	21st to end	Day	19% 8% 3 7% 5% 5% 5% 4 7% 7% 30%	2660
July	1st to 10th	Day	11% 6% 2 6% 5% 5% 5% 4 6% 9% 41%	2576
	11th to 20th	Day	13% 6% 2 6% 5% 5% 6% 5% 8% 10% 36%	2520
	21st to end	Day	12% 5% 3 5% 4 5% 6% 5% 8% 9% 38%	2744
August	1st to 10th	Day	13% 6% 2 7% 6% 5% 6% 4 7% 8% 38%	2506
	11th to 20th	Day	9% 6% 3 7% 5% 5% 5% 4 6% 9% 41%	2272
	21st to end	Day	13% 5% 2 6% 4 4 5% 4 7% 8% 41%	2376
September	1st to 10th	Day	12% 7% 3 6% 4 4 5% 4 6% 8% 41%	2160
	11th to 20th	Day	13% 5% 2 5% 3 4 4 4 5% 7% 48%	2105
	21st to end	Day	16% 6% 3 6% 4 4 4 3 5% 8% 41%	1980
October	1st to 10th	Day	20% 7% 3 7% 4 4 5% 3 4 7% 36%	1828
	11th to 20th	Day	19% 10% 4 9% 6% 5% 5% 4 5% 5% 28%	1785
	21st to end	Day	25% 11% 3 7% 4 4 4 3 6% 6% 27%	1782
November	1st to 10th	Day	16% 10% 3 7% 5% 5% 5% 4 6% 7% 33%	1671
	11th to 20th	Day	18% 11% 3 8% 5% 5% 5% 4 6% 7% 28%	1606
	21st to end	Day	21% 10% 4 8% 6% 5% 6% 4 5% 5% 24%	1520
December	1st to 10th	Day	24% 15% 5% 9% 6% 5% 4 4 5% 5% 19%	1520
	11th to 20th	Day	21% 14% 4 9% 5% 4 4 4 4 5% 25%	1906
	21st to end	Day	28% 18% 5% 9% 5% 4 3 3 3 4 20%	2772
January	1st to 10th	Night	17% 17% 6% 10% 6% 5% 4 3 5% 6% 21%	4429
	11th to 20th	Night	13% 14% 6% 13% 8% 5% 5% 4 6% 6% 21%	4440
	21st to end	Night	15% 18% 6% 11% 6% 5% 4 2 4 5% 24%	4884
February	1st to 10th	Night	15% 14% 5% 12% 7% 5% 5% 4 6% 6% 23%	2480
	11th to 20th	Night	13% 12% 4 11% 6% 5% 5% 5% 6% 5% 28%	2327
	21st to end	Night	15% 15% 5% 10% 5% 4 4 4 4 5% 30%	1884
March	1st to 10th	Night	20% 11% 3 7% 5% 4 4 4 4 4 32%	3724
	11th to 20th	Night	18% 18% 4 10% 5% 4 3 3 4 4 26%	3618
	21st to end	Night	13% 11% 3 8% 5% 5% 4 3 4 5% 39%	3503
April	1st to 10th	Night	23% 10% 3 7% 4 5% 5% 3 4 6% 32%	1900
	11th to 20th	Night	21% 9% 3 7% 4 4 5% 3 5% 6% 34%	1875
	21st to end	Night	21% 9% 2 7% 5% 5% 4 3 5% 6% 34%	1772
May	1st to 10th	Night	21% 10% 3 7% 5% 5% 4 4 5% 7% 30%	2550
	11th to 20th	Night	22% 7% 3 6% 4 4 4 3 5% 7% 37%	2495
	21st to end	Night	15% 7% 3 7% 5% 5% 4 3 6% 8% 37%	2738
June	1st to 10th	Night	20% 7% 2 6% 5% 5% 5% 5% 7% 8% 31%	1520
	11th to 20th	Night	15% 7% 2 6% 4 4 4 4 5% 7% 40%	1520
	21st to end	Night	19% 7% 2 6% 4 5% 5% 5% 6% 7% 34%	1520
July	1st to 10th	Night	11% 4 2 5% 6% 4 6% 4 6% 7% 45%	1478
	11th to 20th	Night	12% 6% 2 5% 6% 4 5% 4 7% 10% 40%	1440
	21st to end	Night	11% 7% 2 5% 4 4 5% 5% 5% 9% 41%	1574
August	1st to 10th	Night	12% 5% 3 5% 3 4 4 5% 6% 8% 44%	1432
	11th to 20th	Night	12% 6% 2 6% 4 5% 4 4 5% 7% 44%	1607
	21st to end	Night	13% 5% 2 6% 4 4 5% 4 6% 8% 42%	1980
September	1st to 10th	Night	11% 6% 3 7% 5% 5% 5% 4 6% 7% 42%	1800
	11th to 20th	Night	15% 6% 2 4 3 2 3 3 4 7% 48%	1854
	21st to end	Night	17% 6% 1 6% 4 5% 4 3 6% 7% 43%	1980
October	1st to 10th	Night	19% 7% 2 7% 5% 4 5% 3 5% 7% 37%	2129
	11th to 20th	Night	20% 8% 3 8% 4 4 5% 3 5% 6% 33%	2173
	21st to end	Night	22% 9% 3 9% 5% 6% 4 3 5% 5% 29%	2574
November	1st to 10th	Night	19% 9% 3 7% 5% 4 5% 4 5% 7% 33%	2407
	11th to 20th	Night	19% 9% 4 8% 6% 5% 5% 4 5% 6% 31%	2571
	21st to end	Night	22% 11% 4 9% 6% 4 4 3 5% 6% 25%	2660
December	1st to 10th	Night	21% 16% 5% 10% 5% 5% 4 4 5% 5% 20%	2660
	11th to 20th	Night	23% 15% 4 9% 5% 4 4 4 4 4 25%	3288
	21st to end	Night	30% 17% 4 9% 4 3 3 3 3 4 21%	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	63% 8% 11% 12% 5% 1	2518
	11th to 20th	Day	57% 7% 14% 14% 8% 1	2520
	21st to end	Day	62% 6% 15% 12% 5%	2772
February	1st to 10th	Day	60% 4 10% 19% 5% 2	1698
	11th to 20th	Day	58% 5% 12% 17% 8% 1	1746
	21st to end	Day	61% 3 10% 14% 10% 2	1570
March	1st to 10th	Day	60% 6% 9% 17% 8% 1	3119
	11th to 20th	Day	56% 7% 11% 14% 9% 2	3338
	21st to end	Day	45% 5% 9% 20% 18% 2	4129
April	1st to 10th	Day	53% 4 8% 20% 12% 2	2280
	11th to 20th	Day	49% 5% 7% 21% 15% 2	2254
	21st to end	Day	54% 5% 8% 16% 13% 4	2406
May	1st to 10th	Day	51% 7% 10% 21% 10% 1	4433
	11th to 20th	Day	49% 8% 14% 18% 9% 2	4402
	21st to end	Day	42% 8% 13% 23% 14% 1	4837
June	1st to 10th	Day	52% 7% 10% 18% 12% 1	2660
	11th to 20th	Day	42% 8% 12% 22% 14% 3	2660
	21st to end	Day	51% 8% 12% 19% 9% 1	2660
July	1st to 10th	Day	38% 8% 13% 27% 14% 1	2506
	11th to 20th	Day	39% 9% 14% 27% 10%	2445
	21st to end	Day	40% 8% 17% 25% 9%	2591
August	1st to 10th	Day	42% 8% 16% 25% 9%	2492
	11th to 20th	Day	38% 8% 18% 26% 10%	2272
	21st to end	Day	38% 7% 15% 26% 13% 1	2376
September	1st to 10th	Day	38% 7% 15% 26% 13%	2160
	11th to 20th	Day	35% 6% 13% 31% 14% 1	2105
	21st to end	Day	42% 6% 15% 27% 10% 1	1980
October	1st to 10th	Day	48% 6% 11% 23% 11%	1828
	11th to 20th	Day	57% 6% 12% 18% 7%	1785
	21st to end	Day	57% 6% 13% 16% 7% 1	1782
November	1st to 10th	Day	49% 6% 15% 21% 8% 1	1671
	11th to 20th	Day	54% 7% 12% 17% 10%	1606
	21st to end	Day	60% 7% 14% 14% 5%	1520
December	1st to 10th	Day	66% 6% 11% 12% 4	1520
	11th to 20th	Day	62% 6% 13% 15% 5%	1906
	21st to end	Day	70% 4 9% 12% 5%	2772
January	1st to 10th	Night	63% 7% 15% 11% 4	4429
	11th to 20th	Night	60% 8% 15% 13% 4	4440
	21st to end	Night	63% 6% 13% 12% 6% 1	4884
February	1st to 10th	Night	60% 5% 12% 17% 6% 1	2480
	11th to 20th	Night	55% 6% 11% 20% 7% 1	2329
	21st to end	Night	56% 4 9% 17% 13% 1	1884
March	1st to 10th	Night	53% 6% 11% 18% 9% 3	3734
	11th to 20th	Night	59% 6% 9% 14% 9% 2	3619
	21st to end	Night	47% 6% 7% 23% 15% 3	3503
April	1st to 10th	Night	54% 4 9% 18% 14% 2	1900
	11th to 20th	Night	51% 5% 8% 21% 14% 2	1875
	21st to end	Night	51% 5% 8% 18% 14% 4	1772
May	1st to 10th	Night	52% 7% 11% 19% 9% 3	2556
	11th to 20th	Night	46% 6% 14% 19% 13% 2	2496
	21st to end	Night	45% 7% 10% 20% 18% 2	2739
June	1st to 10th	Night	49% 7% 13% 20% 11% 1	1520
	11th to 20th	Night	42% 6% 12% 22% 16% 2	1520
	21st to end	Night	46% 8% 12% 19% 13% 1	1520
July	1st to 10th	Night	36% 7% 14% 25% 17% 1	1438
	11th to 20th	Night	38% 7% 13% 30% 12%	1392
	21st to end	Night	38% 7% 17% 25% 12% 1	1486
August	1st to 10th	Night	36% 7% 19% 26% 11%	1422
	11th to 20th	Night	37% 7% 18% 26% 12%	1607
	21st to end	Night	37% 7% 17% 27% 12%	1980
September	1st to 10th	Night	39% 6% 13% 25% 15% 1	1800
	11th to 20th	Night	36% 5% 13% 34% 12% 1	1854
	21st to end	Night	41% 5% 13% 29% 13%	1980
October	1st to 10th	Night	46% 5% 12% 23% 12% 1	2129
	11th to 20th	Night	52% 6% 12% 22% 8%	2173
	21st to end	Night	57% 6% 13% 16% 8% 1	2574
November	1st to 10th	Night	50% 6% 14% 20% 8% 1	2407
	11th to 20th	Night	54% 5% 13% 18% 9% 2	2571
	21st to end	Night	60% 5% 14% 16% 5%	2660
December	1st to 10th	Night	66% 5% 11% 14% 4	2660
	11th to 20th	Night	63% 5% 9% 17% 6%	3288
	21st to end	Night	68% 4 9% 14% 4	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	27% 17% 26% 23% 6% 1	180
	11th to 20th	Day	28% 19% 33% 14% 5% 1	180
	21st to end	Day	21% 15% 35% 22% 7% 1	198
February	1st to 10th	Day	30% 21% 34% 12% 3	265
	11th to 20th	Day	23% 20% 38% 17% 2	344
	21st to end	Day	30% 17% 29% 22% 2	382
March	1st to 10th	Day	24% 17% 32% 22% 5%	460
	11th to 20th	Day	21% 23% 33% 17% 5% 1	460
	21st to end	Day	26% 18% 28% 17% 9% 2	506
April	1st to 10th	Day	28% 15% 30% 18% 7% 2	460
	11th to 20th	Day	26% 20% 28% 16% 8% 2	452
	21st to end	Day	28% 17% 31% 15% 7% 2	460
May	1st to 10th	Day	22% 14% 32% 22% 8% 2	463
	11th to 20th	Day	18% 13% 31% 25% 10% 2	487
	21st to end	Day	19% 15% 31% 24% 10% 2	529
June	1st to 10th	Day	21% 15% 26% 27% 9% 2	490
	11th to 20th	Day	17% 12% 32% 26% 13% 2	490
	21st to end	Day	21% 12% 30% 23% 10% 3	490
July	1st to 10th	Day	11% 10% 28% 30% 16% 5%	461
	11th to 20th	Day	14% 8% 30% 30% 15% 3	444
	21st to end	Day	15% 7% 30% 29% 16% 3	488
August	1st to 10th	Day	16% 6% 26% 30% 18% 4	446
	11th to 20th	Day	11% 7% 24% 32% 17% 8%	439
	21st to end	Day	14% 9% 27% 25% 18% 7%	495
September	1st to 10th	Day	15% 7% 30% 24% 17% 6%	450
	11th to 20th	Day	13% 10% 25% 25% 16% 11%	450
	21st to end	Day	18% 12% 27% 20% 17% 5%	450
October	1st to 10th	Day	23% 10% 28% 21% 14% 3	450
	11th to 20th	Day	22% 19% 27% 20% 11% 1	442
	21st to end	Day	30% 14% 29% 21% 6%	396
November	1st to 10th	Day	27% 15% 26% 22% 8% 1	365
	11th to 20th	Day	24% 20% 33% 18% 4	266
	21st to end	Day	26% 18% 31% 19% 5% 1	180
December	1st to 10th	Day	32% 14% 28% 19% 6% 2	180
	11th to 20th	Day	30% 18% 34% 13% 4 1	180
	21st to end	Day	35% 16% 30% 13% 4 2	198
January	1st to 10th	Night	25% 16% 30% 25% 4	760
	11th to 20th	Night	27% 15% 30% 23% 5% 1	760
	21st to end	Night	18% 14% 36% 25% 7%	836
February	1st to 10th	Night	22% 15% 34% 25% 4	760
	11th to 20th	Night	20% 16% 37% 23% 4	743
	21st to end	Night	22% 14% 33% 26% 4	628
March	1st to 10th	Night	23% 14% 33% 26% 4	760
	11th to 20th	Night	26% 15% 32% 23% 5%	760
	21st to end	Night	22% 13% 31% 26% 8% 1	836
April	1st to 10th	Night	26% 14% 27% 27% 6%	760
	11th to 20th	Night	24% 14% 31% 25% 5% 1	751
	21st to end	Night	27% 10% 31% 23% 9%	632
May	1st to 10th	Night	24% 8% 31% 26% 8% 3	403
	11th to 20th	Night	21% 8% 30% 30% 10% 1	374
	21st to end	Night	16% 8% 35% 31% 10%	411
June	1st to 10th	Night	23% 8% 27% 31% 12% 1	380
	11th to 20th	Night	17% 7% 27% 35% 12% 1	380
	21st to end	Night	21% 6% 27% 31% 15% 1	380
July	1st to 10th	Night	12% 6% 29% 35% 18% 1	360
	11th to 20th	Night	12% 5% 23% 41% 19%	348
	21st to end	Night	12% 4 25% 39% 18% 2	394
August	1st to 10th	Night	15% 3 18% 44% 20% 1	358
	11th to 20th	Night	14% 3 23% 33% 24% 3	543
	21st to end	Night	14% 5% 26% 33% 20% 2	792
September	1st to 10th	Night	13% 4 27% 37% 17% 2	720
	11th to 20th	Night	18% 6% 19% 34% 21% 2	720
	21st to end	Night	18% 8% 25% 28% 19% 2	720
October	1st to 10th	Night	22% 11% 26% 28% 13% 1	720
	11th to 20th	Night	23% 12% 27% 28% 9% 1	720
	21st to end	Night	28% 11% 30% 26% 5%	792
November	1st to 10th	Night	24% 15% 25% 27% 8% 1	740
	11th to 20th	Night	23% 18% 30% 20% 9%	760
	21st to end	Night	29% 15% 29% 19% 7%	760
December	1st to 10th	Night	30% 14% 31% 20% 5%	760
	11th to 20th	Night	29% 18% 31% 17% 5% 1	760
	21st to end	Night	35% 15% 28% 15% 6%	836

Page generated at 2024-07-02 06:41:28. Version ac07

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