Rang St-Joachim
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Rang St-Joachim clear sky chart from 2005-11-06 to 2024-01-27.

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% 9% 4 7% 6% 3 5% 5% 5% 7% 32%	74874
	Night	20% 11% 4 7% 6% 3 4 4 4 6% 30%	75164
Transparency	Day	52% 6% 12% 20% 9% 1	74579
	Night	56% 5% 10% 19% 9% 1	74993
Seeing	Day	24% 11% 27% 24% 12% 3	13545
	Night	25% 9% 27% 28% 10% 1	22643

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	21% 20% 6% 9% 7% 4 3 3 4 4 18%	1517
	11th to 20th	Day	20% 17% 7% 11% 7% 3 5% 4 3 4 20%	1520
	21st to end	Day	12% 14% 5% 9% 7% 4 6% 5% 6% 6% 24%	1632
February	1st to 10th	Day	18% 14% 6% 11% 7% 5% 5% 5% 4 5% 21%	1562
	11th to 20th	Day	16% 14% 7% 9% 7% 3 5% 4 5% 5% 25%	1696
	21st to end	Day	17% 14% 5% 7% 8% 4 5% 5% 5% 6% 24%	1480
March	1st to 10th	Day	15% 13% 5% 9% 6% 3 6% 4 4 6% 28%	1797
	11th to 20th	Day	18% 11% 4 7% 6% 3 4 5% 4 6% 31%	1850
	21st to end	Day	20% 10% 4 7% 5% 3 5% 4 5% 5% 33%	2376
April	1st to 10th	Day	23% 10% 4 6% 6% 4 5% 5% 5% 5% 29%	2160
	11th to 20th	Day	21% 8% 3 6% 5% 3 4 4 5% 6% 36%	2134
	21st to end	Day	23% 8% 4 5% 6% 3 5% 4 4 6% 31%	2323
May	1st to 10th	Day	20% 8% 3 7% 5% 2 4 4 5% 7% 35%	2438
	11th to 20th	Day	18% 6% 4 6% 5% 4 5% 4 5% 7% 37%	2478
	21st to end	Day	16% 7% 4 5% 6% 3 5% 5% 6% 8% 34%	2725
June	1st to 10th	Day	23% 6% 3 6% 6% 3 5% 5% 6% 7% 30%	2520
	11th to 20th	Day	16% 6% 2 6% 5% 3 5% 5% 6% 8% 38%	2520
	21st to end	Day	21% 7% 4 6% 5% 3 5% 5% 5% 7% 32%	2520
July	1st to 10th	Day	13% 6% 2 5% 5% 3 6% 4 6% 9% 40%	2520
	11th to 20th	Day	13% 6% 2 6% 5% 3 6% 6% 8% 9% 37%	2520
	21st to end	Day	14% 7% 2 5% 5% 2 6% 6% 7% 9% 37%	2744
August	1st to 10th	Day	13% 6% 3 6% 6% 4 5% 6% 6% 9% 36%	2506
	11th to 20th	Day	11% 7% 2 5% 5% 3 5% 6% 7% 9% 40%	2275
	21st to end	Day	14% 6% 2 5% 5% 3 5% 4 6% 8% 41%	2376
September	1st to 10th	Day	14% 5% 2 5% 6% 4 4 5% 5% 8% 42%	2160
	11th to 20th	Day	16% 6% 2 4 3 2 3 3 5% 7% 47%	2062
	21st to end	Day	16% 6% 3 6% 5% 2 5% 5% 6% 8% 39%	1980
October	1st to 10th	Day	22% 7% 3 6% 5% 4 5% 6% 6% 6% 30%	1893
	11th to 20th	Day	20% 9% 3 6% 7% 4 4 6% 6% 6% 29%	1742
	21st to end	Day	27% 11% 3 6% 6% 3 4 4 4 5% 28%	1782
November	1st to 10th	Day	19% 11% 3 5% 6% 3 6% 5% 4 7% 32%	1671
	11th to 20th	Day	18% 11% 5% 8% 7% 4 5% 5% 6% 6% 26%	1677
	21st to end	Day	22% 14% 5% 7% 6% 4 5% 5% 4 6% 23%	1520
December	1st to 10th	Day	24% 16% 7% 9% 6% 4 4 4 4 5% 18%	1520
	11th to 20th	Day	23% 13% 5% 8% 6% 3 4 5% 5% 5% 23%	1906
	21st to end	Day	27% 16% 5% 10% 6% 3 4 4 3 4 17%	2772
January	1st to 10th	Night	19% 19% 6% 10% 8% 3 5% 4 3 5% 18%	2649
	11th to 20th	Night	18% 16% 7% 11% 6% 4 5% 4 4 5% 20%	2660
	21st to end	Night	16% 13% 6% 9% 8% 4 5% 4 4 5% 26%	2868
February	1st to 10th	Night	18% 15% 6% 13% 8% 4 5% 3 4 5% 19%	2396
	11th to 20th	Night	16% 12% 6% 10% 8% 4 5% 5% 4 5% 25%	2148
	21st to end	Night	18% 13% 5% 9% 6% 4 4 3 4 5% 29%	1776
March	1st to 10th	Night	18% 15% 5% 8% 7% 3 5% 4 5% 5% 28%	2150
	11th to 20th	Night	21% 12% 4 8% 7% 3 4 3 4 4 30%	2104
	21st to end	Night	21% 11% 4 6% 3 3 5% 4 4 4 36%	1980
April	1st to 10th	Night	24% 10% 4 7% 6% 3 4 4 5% 5% 28%	1800
	11th to 20th	Night	23% 10% 3 6% 5% 3 3 4 3 6% 33%	1775
	21st to end	Night	22% 10% 3 6% 4 3 3 4 4 5% 34%	1636
May	1st to 10th	Night	23% 8% 5% 6% 5% 2 3 4 4 6% 33%	1535
	11th to 20th	Night	19% 9% 3 6% 5% 3 4 4 5% 7% 36%	1415
	21st to end	Night	17% 7% 2 5% 6% 3 5% 5% 5% 7% 39%	1550
June	1st to 10th	Night	25% 6% 2 4 5% 3 5% 5% 5% 7% 31%	1440
	11th to 20th	Night	18% 5% 2 6% 6% 3 4 5% 6% 9% 36%	1440
	21st to end	Night	17% 8% 2 7% 6% 3 4 5% 5% 7% 35%	1440
July	1st to 10th	Night	12% 5% 3 5% 5% 3 6% 5% 6% 9% 41%	1440
	11th to 20th	Night	11% 5% 3 5% 6% 3 6% 6% 7% 9% 40%	1440
	21st to end	Night	13% 5% 2 6% 7% 4 6% 5% 6% 8% 38%	1574
August	1st to 10th	Night	14% 5% 2 4 6% 3 5% 4 7% 9% 41%	1432
	11th to 20th	Night	14% 6% 2 6% 5% 3 4 5% 6% 8% 40%	1605
	21st to end	Night	14% 7% 2 6% 5% 4 4 4 5% 7% 41%	1980
September	1st to 10th	Night	14% 6% 3 5% 5% 3 4 6% 6% 7% 41%	1800
	11th to 20th	Night	16% 5% 2 4 5% 3 3 4 4 7% 47%	1898
	21st to end	Night	18% 7% 2 5% 5% 2 4 5% 5% 6% 41%	1980
October	1st to 10th	Night	19% 7% 3 6% 5% 3 4 5% 5% 6% 36%	2064
	11th to 20th	Night	22% 9% 3 7% 6% 3 4 4 5% 5% 31%	2218
	21st to end	Night	26% 10% 3 8% 6% 2 5% 4 4 5% 27%	2574
November	1st to 10th	Night	20% 11% 4 6% 4 3 5% 6% 5% 6% 31%	2407
	11th to 20th	Night	21% 10% 4 8% 6% 3 4 4 4 5% 30%	2498
	21st to end	Night	23% 13% 5% 7% 6% 3 5% 4 4 5% 25%	2660
December	1st to 10th	Night	24% 18% 7% 9% 7% 4 4 3 4 5% 16%	2660
	11th to 20th	Night	25% 14% 6% 10% 6% 2 4 3 4 4 22%	3288
	21st to end	Night	28% 16% 5% 10% 6% 3 3 3 3 4 20%	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	71% 5% 9% 13% 2	1518
	11th to 20th	Day	70% 4 9% 11% 6%	1520
	21st to end	Day	60% 5% 13% 15% 6% 1	1632
February	1st to 10th	Day	67% 5% 9% 14% 4 1	1562
	11th to 20th	Day	62% 5% 11% 16% 5% 1	1705
	21st to end	Day	61% 5% 11% 15% 7% 1	1480
March	1st to 10th	Day	58% 5% 11% 17% 7% 2	1800
	11th to 20th	Day	54% 5% 14% 15% 11% 1	1850
	21st to end	Day	53% 6% 9% 21% 10% 2	2376
April	1st to 10th	Day	57% 6% 7% 19% 9% 1	2160
	11th to 20th	Day	50% 5% 9% 21% 13% 2	2134
	21st to end	Day	55% 5% 11% 17% 10% 3	2323
May	1st to 10th	Day	49% 5% 10% 20% 14% 2	2438
	11th to 20th	Day	47% 6% 10% 21% 14% 2	2482
	21st to end	Day	47% 7% 13% 19% 12% 1	2725
June	1st to 10th	Day	51% 7% 12% 19% 9% 1	2520
	11th to 20th	Day	43% 7% 11% 24% 13% 2	2520
	21st to end	Day	51% 7% 12% 20% 9% 1	2520
July	1st to 10th	Day	39% 7% 15% 27% 11% 1	2450
	11th to 20th	Day	42% 7% 15% 29% 7%	2445
	21st to end	Day	42% 8% 17% 25% 7% 1	2591
August	1st to 10th	Day	43% 8% 18% 23% 7%	2492
	11th to 20th	Day	38% 9% 18% 24% 10%	2275
	21st to end	Day	40% 7% 15% 27% 11%	2376
September	1st to 10th	Day	40% 8% 13% 27% 11% 1	2160
	11th to 20th	Day	38% 4 12% 33% 12%	2062
	21st to end	Day	42% 7% 15% 26% 9% 1	1980
October	1st to 10th	Day	54% 6% 12% 20% 8%	1893
	11th to 20th	Day	52% 8% 16% 18% 6%	1742
	21st to end	Day	61% 4 12% 17% 5% 1	1782
November	1st to 10th	Day	53% 6% 13% 21% 7% 1	1671
	11th to 20th	Day	59% 6% 12% 15% 8%	1677
	21st to end	Day	62% 8% 13% 14% 3	1520
December	1st to 10th	Day	71% 5% 11% 11% 2	1520
	11th to 20th	Day	63% 6% 12% 14% 4	1906
	21st to end	Day	72% 6% 10% 9% 3	2772
January	1st to 10th	Night	71% 5% 8% 13% 3	2649
	11th to 20th	Night	69% 5% 9% 12% 5%	2660
	21st to end	Night	63% 5% 9% 14% 9% 1	2868
February	1st to 10th	Night	70% 4 8% 13% 5% 1	2396
	11th to 20th	Night	63% 5% 10% 17% 6%	2150
	21st to end	Night	60% 4 8% 16% 10% 1	1776
March	1st to 10th	Night	60% 4 10% 16% 8% 1	2160
	11th to 20th	Night	59% 4 8% 17% 10% 2	2105
	21st to end	Night	54% 4 7% 20% 12% 3	1980
April	1st to 10th	Night	58% 5% 8% 17% 11% 1	1800
	11th to 20th	Night	54% 4 8% 21% 13% 1	1775
	21st to end	Night	54% 5% 8% 18% 13% 3	1636
May	1st to 10th	Night	52% 4 7% 18% 15% 4	1535
	11th to 20th	Night	47% 5% 8% 20% 16% 3	1416
	21st to end	Night	44% 7% 11% 21% 15% 2	1551
June	1st to 10th	Night	51% 6% 11% 22% 9% 1	1440
	11th to 20th	Night	44% 6% 13% 21% 13% 3	1440
	21st to end	Night	46% 8% 14% 20% 12%	1440
July	1st to 10th	Night	39% 8% 14% 24% 15% 1	1400
	11th to 20th	Night	37% 9% 13% 30% 11%	1392
	21st to end	Night	41% 8% 16% 25% 10%	1486
August	1st to 10th	Night	38% 8% 18% 26% 10%	1422
	11th to 20th	Night	40% 8% 15% 24% 12%	1605
	21st to end	Night	41% 8% 13% 26% 11% 1	1980
September	1st to 10th	Night	41% 7% 12% 27% 13% 1	1800
	11th to 20th	Night	38% 4 14% 31% 12% 1	1898
	21st to end	Night	42% 7% 11% 26% 13% 1	1980
October	1st to 10th	Night	48% 6% 13% 22% 11% 1	2064
	11th to 20th	Night	55% 6% 10% 22% 7%	2218
	21st to end	Night	59% 5% 11% 15% 8% 1	2574
November	1st to 10th	Night	55% 5% 11% 20% 7% 1	2407
	11th to 20th	Night	56% 6% 10% 17% 9% 1	2498
	21st to end	Night	63% 5% 12% 15% 5%	2660
December	1st to 10th	Night	73% 4 10% 11% 2	2660
	11th to 20th	Night	68% 5% 9% 14% 4	3288
	21st to end	Night	71% 5% 9% 12% 2	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	31% 10% 26% 23% 9% 2	180
	11th to 20th	Day	32% 16% 29% 16% 6% 1	180
	21st to end	Day	22% 15% 36% 18% 9% 1	188
February	1st to 10th	Day	34% 20% 32% 14% 1	214
	11th to 20th	Day	29% 14% 34% 20% 4	364
	21st to end	Day	27% 13% 30% 25% 5%	346
March	1st to 10th	Day	28% 10% 30% 26% 6%	420
	11th to 20th	Day	27% 11% 34% 20% 7% 2	420
	21st to end	Day	31% 15% 24% 20% 9% 1	462
April	1st to 10th	Day	31% 14% 25% 20% 10% 1	420
	11th to 20th	Day	29% 16% 25% 16% 9% 4	412
	21st to end	Day	30% 10% 32% 15% 12% 2	420
May	1st to 10th	Day	29% 10% 28% 18% 13% 2	423
	11th to 20th	Day	19% 11% 29% 28% 9% 4	447
	21st to end	Day	18% 9% 33% 25% 12% 2	485
June	1st to 10th	Day	25% 10% 26% 28% 9% 2	450
	11th to 20th	Day	20% 8% 26% 31% 14% 3	450
	21st to end	Day	22% 8% 29% 25% 12% 3	450
July	1st to 10th	Day	14% 5% 25% 36% 16% 5%	445
	11th to 20th	Day	16% 5% 28% 30% 16% 5%	444
	21st to end	Day	19% 5% 21% 35% 18% 2	488
August	1st to 10th	Day	14% 5% 24% 29% 22% 5%	446
	11th to 20th	Day	16% 4 21% 32% 19% 7%	439
	21st to end	Day	16% 10% 23% 24% 19% 8%	495
September	1st to 10th	Day	15% 8% 25% 26% 18% 8%	450
	11th to 20th	Day	16% 8% 22% 23% 20% 11%	450
	21st to end	Day	16% 8% 27% 23% 19% 7%	450
October	1st to 10th	Day	23% 10% 28% 19% 16% 5%	450
	11th to 20th	Day	27% 14% 25% 22% 11% 2	421
	21st to end	Day	37% 11% 21% 24% 5%	396
November	1st to 10th	Day	29% 14% 29% 21% 7% 1	365
	11th to 20th	Day	28% 18% 26% 17% 11% 1	337
	21st to end	Day	32% 17% 23% 22% 6% 1	180
December	1st to 10th	Day	36% 13% 20% 21% 8% 2	180
	11th to 20th	Day	26% 18% 38% 12% 6%	180
	21st to end	Day	35% 15% 28% 17% 4 2	198
January	1st to 10th	Night	29% 12% 31% 23% 5% 1	760
	11th to 20th	Night	27% 12% 32% 22% 6%	760
	21st to end	Night	24% 10% 30% 28% 7% 1	820
February	1st to 10th	Night	27% 9% 33% 26% 5%	720
	11th to 20th	Night	23% 11% 35% 27% 4 1	703
	21st to end	Night	26% 10% 31% 28% 5%	592
March	1st to 10th	Night	27% 12% 27% 30% 4	720
	11th to 20th	Night	29% 12% 26% 25% 8%	720
	21st to end	Night	29% 11% 26% 26% 7% 1	792
April	1st to 10th	Night	29% 10% 27% 28% 6%	720
	11th to 20th	Night	30% 11% 28% 23% 8%	711
	21st to end	Night	28% 10% 28% 26% 7% 1	556
May	1st to 10th	Night	27% 6% 29% 26% 11% 1	455
	11th to 20th	Night	23% 8% 29% 31% 9% 1	354
	21st to end	Night	19% 7% 29% 35% 9% 1	389
June	1st to 10th	Night	29% 6% 25% 29% 11% 1	360
	11th to 20th	Night	21% 4 26% 33% 17%	360
	21st to end	Night	20% 5% 24% 36% 14% 1	360
July	1st to 10th	Night	11% 4 27% 42% 14% 1	350
	11th to 20th	Night	10% 2 21% 49% 16% 1	348
	21st to end	Night	13% 4 19% 48% 16% 1	394
August	1st to 10th	Night	15% 3 16% 41% 25% 1	358
	11th to 20th	Night	18% 3 16% 37% 25% 1	541
	21st to end	Night	17% 6% 18% 37% 21% 2	792
September	1st to 10th	Night	16% 7% 20% 40% 16% 2	720
	11th to 20th	Night	19% 5% 18% 34% 21% 4	720
	21st to end	Night	21% 6% 26% 26% 18% 3	720
October	1st to 10th	Night	24% 6% 26% 29% 15% 1	720
	11th to 20th	Night	29% 7% 27% 27% 9% 1	720
	21st to end	Night	32% 8% 29% 24% 6%	792
November	1st to 10th	Night	26% 12% 31% 23% 7% 1	740
	11th to 20th	Night	27% 14% 27% 22% 9% 1	760
	21st to end	Night	32% 11% 31% 20% 7%	760
December	1st to 10th	Night	34% 13% 28% 20% 5%	760
	11th to 20th	Night	31% 12% 30% 21% 5% 1	760
	21st to end	Night	34% 12% 31% 19% 4	836

Page generated at 2024-01-24 09:37:30. Version ac07

Copyright 2024 Attilla Danko