Ferme Véronneau
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Ferme Véronneau clear sky chart from 2005-11-06 to 2024-01-31.

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	19% 12% 5% 8% 6% 3 5% 4 5% 6% 27%	74927
	Night	18% 13% 5% 9% 7% 3 4 4 4 5% 26%	75196
Transparency	Day	58% 6% 11% 16% 8% 1	74632
	Night	61% 6% 10% 15% 7% 1	75025
Seeing	Day	28% 19% 28% 17% 7% 2	13647
	Night	27% 17% 26% 22% 8% 1	22672

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	15% 19% 10% 14% 10% 5% 5% 5% 3 4 11%	1517
	11th to 20th	Day	15% 18% 7% 14% 10% 4 4 4 3 5% 16%	1520
	21st to end	Day	9% 17% 8% 13% 9% 5% 6% 4 4 5% 19%	1664
February	1st to 10th	Day	15% 17% 8% 14% 11% 5% 7% 4 3 4 14%	1514
	11th to 20th	Day	12% 17% 11% 15% 9% 4 5% 4 4 4 15%	1748
	21st to end	Day	11% 18% 8% 11% 9% 5% 6% 4 4 5% 19%	1480
March	1st to 10th	Day	13% 18% 6% 12% 8% 4 4 3 4 5% 23%	1797
	11th to 20th	Day	15% 15% 8% 9% 7% 3 4 3 4 4 28%	1867
	21st to end	Day	18% 17% 5% 10% 6% 3 3 3 2 4 27%	2337
April	1st to 10th	Day	22% 16% 5% 10% 5% 3 4 3 4 4 26%	2160
	11th to 20th	Day	20% 14% 4 6% 5% 3 4 4 3 5% 33%	2169
	21st to end	Day	24% 14% 5% 6% 5% 3 4 4 5% 5% 26%	2340
May	1st to 10th	Day	24% 11% 3 6% 5% 3 4 3 4 6% 31%	2359
	11th to 20th	Day	21% 8% 4 6% 6% 3 5% 4 5% 6% 31%	2478
	21st to end	Day	19% 7% 3 7% 6% 4 5% 5% 6% 9% 29%	2725
June	1st to 10th	Day	28% 9% 3 5% 4 3 5% 5% 5% 8% 25%	2520
	11th to 20th	Day	18% 7% 2 7% 5% 3 5% 5% 5% 8% 34%	2520
	21st to end	Day	22% 8% 3 7% 6% 3 5% 5% 5% 7% 28%	2520
July	1st to 10th	Day	18% 7% 3 5% 5% 3 5% 5% 6% 10% 33%	2520
	11th to 20th	Day	15% 7% 3 6% 6% 4 6% 6% 8% 10% 29%	2520
	21st to end	Day	19% 6% 3 6% 6% 3 6% 5% 7% 9% 29%	2744
August	1st to 10th	Day	17% 7% 3 7% 7% 4 5% 6% 7% 10% 30%	2476
	11th to 20th	Day	16% 6% 3 6% 6% 4 6% 6% 8% 9% 31%	2304
	21st to end	Day	18% 7% 3 4 5% 4 5% 6% 5% 9% 35%	2390
September	1st to 10th	Day	17% 6% 2 5% 5% 3 5% 5% 5% 7% 39%	2160
	11th to 20th	Day	19% 7% 3 5% 4 2 4 4 4 6% 42%	2013
	21st to end	Day	19% 8% 3 4 5% 3 5% 5% 5% 10% 34%	1980
October	1st to 10th	Day	24% 11% 4 6% 5% 3 5% 4 6% 6% 28%	1967
	11th to 20th	Day	21% 12% 4 7% 5% 4 4 5% 6% 6% 27%	1689
	21st to end	Day	25% 21% 4 5% 5% 4 3 3 3 4 22%	1782
November	1st to 10th	Day	20% 15% 4 7% 6% 3 4 4 4 5% 27%	1671
	11th to 20th	Day	18% 16% 7% 10% 6% 4 3 5% 4 5% 22%	1710
	21st to end	Day	18% 16% 7% 10% 6% 4 5% 4 5% 6% 18%	1568
December	1st to 10th	Day	18% 22% 9% 11% 8% 4 2 3 2 4 15%	1520
	11th to 20th	Day	17% 18% 7% 12% 7% 3 5% 4 4 4 19%	1906
	21st to end	Day	22% 18% 6% 13% 8% 3 4 4 3 3 15%	2772
January	1st to 10th	Night	16% 20% 9% 14% 10% 4 6% 4 3 4 11%	2649
	11th to 20th	Night	14% 18% 8% 14% 10% 4 6% 4 3 3 14%	2660
	21st to end	Night	11% 15% 8% 14% 11% 5% 5% 5% 4 4 18%	2919
February	1st to 10th	Night	13% 16% 8% 15% 11% 5% 6% 4 4 4 15%	2443
	11th to 20th	Night	11% 18% 7% 15% 10% 6% 5% 3 3 3 18%	2098
	21st to end	Night	13% 16% 9% 9% 10% 4 5% 3 3 4 23%	1776
March	1st to 10th	Night	15% 18% 7% 10% 8% 3 4 4 4 4 23%	2150
	11th to 20th	Night	17% 15% 6% 8% 7% 4 4 4 3 5% 26%	2091
	21st to end	Night	18% 16% 6% 10% 5% 3 3 3 3 4 28%	2016
April	1st to 10th	Night	22% 16% 5% 7% 6% 3 4 4 5% 4 25%	1800
	11th to 20th	Night	21% 12% 4 6% 5% 2 4 3 4 6% 32%	1739
	21st to end	Night	23% 13% 3 6% 6% 3 4 4 4 6% 28%	1620
May	1st to 10th	Night	24% 10% 4 7% 5% 3 3 4 4 5% 30%	1616
	11th to 20th	Night	20% 9% 3 5% 6% 4 4 5% 5% 6% 33%	1415
	21st to end	Night	19% 6% 3 6% 5% 4 6% 5% 5% 8% 34%	1550
June	1st to 10th	Night	27% 8% 4 5% 4 2 4 5% 6% 6% 29%	1440
	11th to 20th	Night	20% 6% 3 5% 4 3 5% 6% 6% 7% 36%	1440
	21st to end	Night	20% 6% 3 6% 6% 2 6% 6% 5% 9% 30%	1440
July	1st to 10th	Night	16% 6% 3 5% 6% 3 6% 5% 6% 8% 36%	1440
	11th to 20th	Night	12% 6% 3 5% 5% 3 6% 5% 7% 10% 37%	1440
	21st to end	Night	14% 7% 2 6% 6% 4 6% 5% 6% 8% 36%	1574
August	1st to 10th	Night	17% 5% 2 4 5% 3 4 6% 7% 9% 37%	1444
	11th to 20th	Night	16% 6% 4 6% 5% 3 5% 6% 5% 8% 37%	1596
	21st to end	Night	16% 7% 3 5% 6% 3 4 4 4 7% 41%	1962
September	1st to 10th	Night	17% 8% 3 5% 5% 3 5% 4 5% 6% 40%	1800
	11th to 20th	Night	18% 6% 2 5% 4 2 4 4 4 7% 45%	1946
	21st to end	Night	22% 6% 2 4 3 3 3 4 5% 8% 40%	1980
October	1st to 10th	Night	21% 9% 3 6% 6% 2 3 4 5% 6% 33%	1989
	11th to 20th	Night	23% 13% 3 7% 7% 3 4 4 4 5% 27%	2269
	21st to end	Night	26% 15% 3 6% 5% 3 3 5% 5% 5% 23%	2574
November	1st to 10th	Night	20% 16% 4 7% 6% 4 4 4 4 6% 26%	2407
	11th to 20th	Night	18% 15% 7% 10% 7% 2 4 3 4 5% 25%	2470
	21st to end	Night	18% 18% 7% 12% 7% 3 3 4 3 4 21%	2611
December	1st to 10th	Night	19% 22% 8% 13% 8% 3 5% 4 4 4 12%	2660
	11th to 20th	Night	17% 21% 8% 15% 8% 3 5% 3 3 3 14%	3288
	21st to end	Night	22% 18% 7% 12% 8% 3 4 4 3 3 15%	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	78% 5% 8% 8% 2	1518
	11th to 20th	Day	72% 6% 7% 9% 5% 1	1520
	21st to end	Day	68% 5% 8% 12% 6% 1	1664
February	1st to 10th	Day	76% 4 5% 9% 4 1	1514
	11th to 20th	Day	74% 5% 8% 8% 5% 1	1757
	21st to end	Day	68% 5% 8% 11% 6% 1	1480
March	1st to 10th	Day	67% 4 8% 13% 6% 3	1800
	11th to 20th	Day	61% 4 11% 12% 11% 1	1867
	21st to end	Day	63% 3 7% 16% 9% 2	2337
April	1st to 10th	Day	63% 4 8% 14% 8% 2	2160
	11th to 20th	Day	55% 4 8% 20% 12% 1	2169
	21st to end	Day	60% 6% 9% 14% 8% 3	2340
May	1st to 10th	Day	56% 5% 8% 19% 12% 1	2359
	11th to 20th	Day	52% 7% 10% 18% 11% 1	2482
	21st to end	Day	50% 10% 14% 17% 9% 1	2725
June	1st to 10th	Day	58% 6% 12% 16% 6% 1	2520
	11th to 20th	Day	47% 7% 12% 23% 10% 1	2520
	21st to end	Day	55% 9% 12% 17% 7%	2520
July	1st to 10th	Day	46% 8% 14% 23% 9%	2450
	11th to 20th	Day	47% 10% 14% 23% 6%	2445
	21st to end	Day	51% 8% 14% 20% 6%	2591
August	1st to 10th	Day	49% 9% 17% 20% 5%	2462
	11th to 20th	Day	47% 10% 17% 17% 8%	2304
	21st to end	Day	46% 8% 13% 21% 11%	2390
September	1st to 10th	Day	45% 7% 14% 25% 10%	2160
	11th to 20th	Day	44% 5% 11% 27% 13% 1	2013
	21st to end	Day	46% 9% 13% 21% 10% 1	1980
October	1st to 10th	Day	56% 7% 12% 17% 8%	1967
	11th to 20th	Day	55% 8% 15% 16% 6%	1689
	21st to end	Day	67% 4 9% 12% 6% 1	1782
November	1st to 10th	Day	60% 6% 11% 16% 7% 1	1671
	11th to 20th	Day	65% 6% 10% 10% 7% 2	1710
	21st to end	Day	68% 6% 12% 11% 2	1568
December	1st to 10th	Day	76% 5% 8% 8% 3	1520
	11th to 20th	Day	69% 5% 6% 13% 6% 1	1906
	21st to end	Day	75% 7% 5% 9% 4	2772
January	1st to 10th	Night	78% 5% 7% 7% 3	2649
	11th to 20th	Night	77% 5% 7% 8% 3	2660
	21st to end	Night	71% 5% 7% 10% 5% 1	2919
February	1st to 10th	Night	74% 5% 6% 10% 5%	2443
	11th to 20th	Night	72% 4 6% 12% 5%	2100
	21st to end	Night	67% 4 7% 12% 9% 1	1776
March	1st to 10th	Night	66% 4 8% 14% 6% 2	2160
	11th to 20th	Night	62% 6% 8% 13% 10% 2	2092
	21st to end	Night	61% 4 6% 17% 9% 2	2016
April	1st to 10th	Night	62% 5% 9% 13% 10% 1	1800
	11th to 20th	Night	53% 5% 10% 20% 12% 1	1739
	21st to end	Night	58% 6% 9% 15% 10% 2	1620
May	1st to 10th	Night	56% 5% 7% 17% 13% 1	1616
	11th to 20th	Night	50% 7% 11% 17% 13% 2	1416
	21st to end	Night	49% 8% 12% 20% 10% 1	1551
June	1st to 10th	Night	54% 7% 10% 21% 8% 1	1440
	11th to 20th	Night	46% 8% 11% 22% 9% 3	1440
	21st to end	Night	52% 8% 14% 18% 7%	1440
July	1st to 10th	Night	43% 10% 14% 22% 11%	1400
	11th to 20th	Night	40% 11% 16% 27% 7%	1392
	21st to end	Night	45% 9% 15% 22% 8%	1486
August	1st to 10th	Night	40% 9% 20% 26% 5%	1434
	11th to 20th	Night	44% 9% 17% 20% 10%	1596
	21st to end	Night	43% 7% 16% 25% 10%	1962
September	1st to 10th	Night	44% 7% 14% 24% 10%	1800
	11th to 20th	Night	41% 6% 15% 28% 10% 1	1946
	21st to end	Night	43% 7% 14% 25% 10% 2	1980
October	1st to 10th	Night	52% 6% 12% 20% 10% 1	1989
	11th to 20th	Night	58% 7% 12% 17% 5%	2269
	21st to end	Night	63% 7% 10% 13% 7% 1	2574
November	1st to 10th	Night	61% 6% 10% 15% 7% 1	2407
	11th to 20th	Night	63% 5% 9% 15% 7% 2	2470
	21st to end	Night	68% 6% 10% 12% 4	2611
December	1st to 10th	Night	78% 6% 6% 8% 2	2660
	11th to 20th	Night	78% 4 5% 8% 5%	3288
	21st to end	Night	74% 6% 6% 10% 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% 23% 34% 13% 2	180
	11th to 20th	Day	32% 29% 27% 9% 3 1	180
	21st to end	Day	27% 25% 32% 11% 5% 1	196
February	1st to 10th	Day	43% 29% 20% 8%	202
	11th to 20th	Day	32% 30% 27% 9% 2	416
	21st to end	Day	30% 29% 26% 14% 1	346
March	1st to 10th	Day	31% 22% 30% 14% 3	420
	11th to 20th	Day	29% 29% 25% 13% 4	420
	21st to end	Day	34% 20% 24% 15% 6% 1	462
April	1st to 10th	Day	37% 20% 24% 13% 5% 1	420
	11th to 20th	Day	34% 22% 25% 10% 7% 2	412
	21st to end	Day	34% 24% 24% 13% 4 1	420
May	1st to 10th	Day	40% 17% 24% 13% 5% 1	423
	11th to 20th	Day	27% 20% 31% 16% 4 2	447
	21st to end	Day	23% 20% 33% 18% 6% 1	485
June	1st to 10th	Day	34% 15% 30% 14% 6%	450
	11th to 20th	Day	23% 19% 28% 20% 9% 1	450
	21st to end	Day	25% 16% 33% 16% 9% 2	450
July	1st to 10th	Day	21% 12% 31% 25% 9% 1	445
	11th to 20th	Day	18% 12% 36% 23% 8% 2	444
	21st to end	Day	20% 10% 36% 25% 6% 2	488
August	1st to 10th	Day	18% 12% 30% 26% 12% 2	446
	11th to 20th	Day	19% 9% 30% 23% 15% 4	439
	21st to end	Day	25% 15% 23% 21% 12% 4	495
September	1st to 10th	Day	22% 14% 27% 20% 14% 4	450
	11th to 20th	Day	23% 14% 21% 20% 15% 7%	450
	21st to end	Day	19% 17% 24% 23% 12% 5%	450
October	1st to 10th	Day	27% 18% 23% 17% 11% 3	450
	11th to 20th	Day	29% 21% 25% 15% 8% 2	394
	21st to end	Day	36% 23% 22% 13% 5%	396
November	1st to 10th	Day	34% 19% 27% 15% 4 1	365
	11th to 20th	Day	31% 24% 26% 13% 5% 1	370
	21st to end	Day	32% 21% 30% 14% 2	228
December	1st to 10th	Day	32% 24% 27% 12% 6%	180
	11th to 20th	Day	36% 29% 25% 9% 1	180
	21st to end	Day	41% 22% 28% 7% 2	198
January	1st to 10th	Night	28% 26% 29% 15% 3	760
	11th to 20th	Night	25% 27% 29% 15% 3	760
	21st to end	Night	21% 25% 30% 20% 4	835
February	1st to 10th	Night	25% 26% 29% 18% 3	720
	11th to 20th	Night	24% 25% 32% 15% 3	703
	21st to end	Night	26% 20% 32% 19% 2	592
March	1st to 10th	Night	27% 22% 29% 19% 3	720
	11th to 20th	Night	30% 20% 27% 17% 6%	720
	21st to end	Night	32% 18% 24% 18% 7% 1	792
April	1st to 10th	Night	34% 19% 24% 18% 4	720
	11th to 20th	Night	30% 19% 25% 19% 7%	675
	21st to end	Night	32% 15% 28% 19% 5%	540
May	1st to 10th	Night	30% 13% 29% 21% 6% 1	536
	11th to 20th	Night	23% 12% 33% 24% 7% 1	354
	21st to end	Night	22% 11% 26% 32% 7% 1	389
June	1st to 10th	Night	31% 8% 25% 26% 9% 1	360
	11th to 20th	Night	20% 9% 25% 34% 12%	360
	21st to end	Night	19% 8% 29% 35% 10%	360
July	1st to 10th	Night	17% 6% 29% 34% 13% 1	350
	11th to 20th	Night	14% 5% 28% 35% 16% 1	348
	21st to end	Night	15% 6% 25% 38% 16%	394
August	1st to 10th	Night	19% 4 18% 39% 19% 1	370
	11th to 20th	Night	18% 7% 22% 34% 18% 1	532
	21st to end	Night	20% 6% 23% 32% 17% 2	774
September	1st to 10th	Night	20% 8% 26% 32% 14% 1	720
	11th to 20th	Night	22% 8% 20% 29% 18% 3	720
	21st to end	Night	24% 11% 25% 24% 14% 2	720
October	1st to 10th	Night	29% 12% 23% 23% 13% 1	720
	11th to 20th	Night	31% 16% 23% 20% 8% 2	720
	21st to end	Night	35% 17% 26% 18% 4	792
November	1st to 10th	Night	33% 15% 29% 17% 5%	740
	11th to 20th	Night	27% 21% 28% 15% 7% 1	760
	21st to end	Night	29% 24% 26% 15% 5% 1	760
December	1st to 10th	Night	33% 25% 26% 13% 3	760
	11th to 20th	Night	31% 24% 27% 14% 4	760
	21st to end	Night	33% 23% 26% 15% 2	836

Page generated at 2024-01-28 05:26:36. Version ac07

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