Chimnissing
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Chimnissing clear sky chart from 2005-11-06 to 2024-03-01.

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	16% 11% 4 8% 6% 3 4 4 5% 6% 32%	78454
	Night	18% 14% 6% 10% 7% 3 4 4 4 5% 25%	80931
Transparency	Day	52% 8% 11% 18% 9% 1	78159
	Night	60% 8% 10% 14% 7% 1	80761
Seeing	Day	19% 10% 25% 27% 15% 4	14015
	Night	22% 12% 26% 25% 12% 2	23306

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	17% 22% 13% 13% 13% 3 3 3 2 3 7%	2208
	11th to 20th	Day	12% 18% 10% 22% 17% 6% 4 3 3 2 3	2681
	21st to end	Day	17% 21% 8% 15% 10% 4 5% 4 3 3 9%	3124
February	1st to 10th	Day	14% 15% 7% 18% 11% 5% 5% 3 4 4 13%	1710
	11th to 20th	Day	13% 14% 7% 14% 10% 5% 6% 5% 4 5% 18%	1663
	21st to end	Day	16% 15% 7% 11% 7% 5% 6% 4 4 5% 20%	1475
March	1st to 10th	Day	13% 12% 4 8% 8% 4 4 5% 5% 5% 32%	1949
	11th to 20th	Day	13% 11% 5% 9% 7% 4 5% 5% 5% 6% 33%	1980
	21st to end	Day	18% 9% 3 5% 5% 3 5% 4 4 6% 37%	2178
April	1st to 10th	Day	19% 10% 3 7% 6% 3 4 4 5% 6% 32%	2103
	11th to 20th	Day	19% 8% 3 5% 4 3 5% 3 4 6% 39%	2268
	21st to end	Day	20% 9% 2 6% 5% 2 4 3 5% 7% 36%	2340
May	1st to 10th	Day	18% 6% 3 5% 5% 3 4 4 5% 8% 39%	2340
	11th to 20th	Day	14% 7% 3 5% 5% 3 4 4 5% 5% 46%	2460
	21st to end	Day	12% 5% 2 5% 5% 3 5% 4 5% 8% 45%	2725
June	1st to 10th	Day	15% 5% 2 5% 4 3 4 5% 6% 7% 43%	2572
	11th to 20th	Day	12% 5% 2 5% 5% 3 4 5% 5% 9% 46%	2700
	21st to end	Day	13% 6% 2 5% 4 3 5% 5% 6% 8% 44%	2700
July	1st to 10th	Day	10% 4 3 4 4 2 4 4 6% 8% 51%	2700
	11th to 20th	Day	12% 5% 2 4 4 3 4 4 6% 7% 50%	2620
	21st to end	Day	9% 5% 2 5% 6% 3 5% 5% 6% 8% 47%	2577
August	1st to 10th	Day	12% 5% 2 4 4 3 3 5% 6% 9% 48%	2327
	11th to 20th	Day	11% 4 2 5% 4 3 5% 4 6% 8% 48%	2303
	21st to end	Day	12% 6% 3 5% 6% 3 4 5% 6% 8% 42%	2525
September	1st to 10th	Day	14% 6% 2 5% 6% 4 4 5% 4 7% 42%	2160
	11th to 20th	Day	15% 5% 3 4 4 3 4 4 5% 7% 45%	2016
	21st to end	Day	19% 6% 3 6% 6% 4 5% 4 4 6% 37%	1969
October	1st to 10th	Day	21% 8% 2 5% 5% 4 5% 5% 4 7% 34%	1800
	11th to 20th	Day	26% 11% 3 9% 7% 4 5% 5% 4 6% 22%	1800
	21st to end	Day	33% 15% 3 8% 5% 3 3 4 4 4 18%	1955
November	1st to 10th	Day	21% 16% 5% 8% 6% 4 5% 3 4 6% 23%	1571
	11th to 20th	Day	19% 21% 7% 10% 6% 3 4 4 4 5% 16%	1520
	21st to end	Day	23% 24% 7% 11% 6% 4 4 4 3 4 10%	1520
December	1st to 10th	Day	19% 27% 11% 16% 7% 2 3 3 3 4 5%	1520
	11th to 20th	Day	21% 21% 8% 18% 8% 4 3 2 3 4 7%	1906
	21st to end	Day	25% 21% 8% 15% 8% 4 4 3 3 2 8%	2489
January	1st to 10th	Night	18% 26% 11% 15% 11% 3 3 3 2 2 5%	4748
	11th to 20th	Night	15% 18% 9% 20% 14% 4 5% 4 3 3 5%	4273
	21st to end	Night	18% 19% 9% 14% 13% 5% 5% 3 3 3 8%	4532
February	1st to 10th	Night	15% 17% 9% 17% 9% 4 5% 4 4 4 13%	2470
	11th to 20th	Night	14% 16% 8% 16% 8% 3 6% 3 4 4 19%	2403
	21st to end	Night	18% 11% 6% 11% 9% 4 5% 4 4 5% 22%	1975
March	1st to 10th	Night	15% 11% 6% 8% 7% 3 3 3 4 6% 33%	2004
	11th to 20th	Night	14% 12% 7% 10% 8% 3 4 4 3 5% 32%	1979
	21st to end	Night	17% 10% 4 7% 5% 3 4 4 4 6% 35%	2178
April	1st to 10th	Night	21% 10% 4 7% 6% 3 5% 4 4 6% 31%	1855
	11th to 20th	Night	19% 9% 3 5% 5% 3 5% 3 5% 7% 37%	1656
	21st to end	Night	19% 9% 4 8% 6% 3 5% 4 4 7% 32%	1620
May	1st to 10th	Night	16% 7% 3 5% 6% 3 5% 4 5% 8% 38%	1620
	11th to 20th	Night	16% 5% 3 6% 5% 3 4 4 4 7% 43%	1433
	21st to end	Night	11% 4 2 4 6% 3 4 5% 6% 7% 48%	1550
June	1st to 10th	Night	15% 5% 3 6% 6% 4 5% 5% 6% 8% 39%	1383
	11th to 20th	Night	11% 5% 3 3 5% 2 7% 6% 6% 10% 42%	1260
	21st to end	Night	13% 7% 2 6% 5% 3 4 4 6% 8% 42%	1260
July	1st to 10th	Night	10% 4 1 4 4 2 3 5% 5% 8% 54%	1260
	11th to 20th	Night	10% 5% 2 5% 5% 3 5% 5% 6% 7% 47%	1336
	21st to end	Night	9% 4 2 5% 5% 3 5% 4 6% 8% 50%	1738
August	1st to 10th	Night	11% 4 2 4 4 3 5% 5% 7% 7% 48%	1611
	11th to 20th	Night	10% 5% 3 5% 5% 3 5% 5% 5% 8% 48%	1598
	21st to end	Night	15% 6% 3 6% 5% 3 5% 4 4 8% 42%	1813
September	1st to 10th	Night	13% 5% 3 5% 5% 2 4 4 6% 9% 44%	1800
	11th to 20th	Night	17% 5% 3 4 5% 2 4 4 5% 8% 43%	1942
	21st to end	Night	21% 5% 3 6% 6% 3 4 4 5% 6% 37%	1989
October	1st to 10th	Night	23% 8% 2 7% 6% 4 4 4 4 5% 33%	2160
	11th to 20th	Night	28% 11% 4 8% 6% 4 4 3 4 6% 23%	2160
	21st to end	Night	32% 16% 4 7% 5% 3 3 4 5% 4 17%	2398
November	1st to 10th	Night	23% 15% 4 7% 6% 3 4 4 4 5% 25%	2505
	11th to 20th	Night	20% 22% 6% 10% 5% 2 4 5% 4 5% 17%	2660
	21st to end	Night	24% 26% 8% 9% 5% 3 4 3 3 4 12%	2660
December	1st to 10th	Night	23% 29% 11% 12% 5% 2 3 2 2 2 7%	2660
	11th to 20th	Night	19% 22% 10% 16% 7% 3 4 3 3 4 10%	3288
	21st to end	Night	26% 23% 10% 15% 6% 3 3 2 2 3 6%	5154

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	77% 13% 6% 3	2209
	11th to 20th	Day	80% 13% 3 2 1	2681
	21st to end	Day	77% 10% 7% 5% 1	3124
February	1st to 10th	Day	73% 8% 9% 8% 2	1710
	11th to 20th	Day	65% 8% 12% 10% 4	1672
	21st to end	Day	65% 7% 11% 12% 4	1475
March	1st to 10th	Day	54% 8% 14% 16% 8%	1952
	11th to 20th	Day	52% 7% 12% 18% 9% 2	1980
	21st to end	Day	48% 6% 11% 18% 15% 2	2178
April	1st to 10th	Day	53% 6% 11% 19% 10% 1	2103
	11th to 20th	Day	47% 6% 9% 23% 14% 1	2268
	21st to end	Day	48% 6% 12% 19% 12% 3	2340
May	1st to 10th	Day	44% 6% 11% 23% 14% 3	2340
	11th to 20th	Day	41% 7% 9% 25% 17% 2	2464
	21st to end	Day	37% 8% 14% 23% 15% 2	2725
June	1st to 10th	Day	38% 9% 12% 24% 16% 1	2572
	11th to 20th	Day	35% 7% 14% 25% 17% 1	2700
	21st to end	Day	38% 9% 15% 24% 14% 1	2700
July	1st to 10th	Day	29% 9% 16% 27% 18% 2	2626
	11th to 20th	Day	32% 9% 15% 31% 12% 1	2539
	21st to end	Day	35% 10% 15% 26% 14% 1	2433
August	1st to 10th	Day	33% 9% 18% 25% 14% 1	2314
	11th to 20th	Day	32% 10% 19% 27% 12%	2303
	21st to end	Day	38% 10% 16% 24% 11% 1	2525
September	1st to 10th	Day	41% 8% 14% 25% 11% 1	2160
	11th to 20th	Day	38% 8% 16% 28% 10%	2016
	21st to end	Day	47% 9% 12% 25% 7%	1969
October	1st to 10th	Day	49% 9% 12% 18% 10% 1	1800
	11th to 20th	Day	64% 8% 11% 12% 5% 1	1800
	21st to end	Day	70% 8% 10% 8% 4	1955
November	1st to 10th	Day	62% 9% 10% 14% 5%	1571
	11th to 20th	Day	70% 8% 10% 7% 4	1520
	21st to end	Day	77% 8% 8% 5% 1	1520
December	1st to 10th	Day	84% 7% 6% 3 1	1520
	11th to 20th	Day	81% 8% 6% 5%	1906
	21st to end	Day	81% 9% 5% 4	2489
January	1st to 10th	Night	82% 11% 5% 3	4748
	11th to 20th	Night	77% 14% 6% 2 1	4273
	21st to end	Night	78% 10% 7% 4 1	4532
February	1st to 10th	Night	74% 6% 9% 9% 2	2470
	11th to 20th	Night	67% 8% 9% 13% 3	2405
	21st to end	Night	63% 7% 12% 13% 5%	1975
March	1st to 10th	Night	54% 7% 12% 17% 9% 1	2014
	11th to 20th	Night	55% 6% 10% 16% 11% 2	1980
	21st to end	Night	50% 6% 11% 18% 14% 2	2178
April	1st to 10th	Night	55% 6% 9% 18% 11% 1	1855
	11th to 20th	Night	48% 5% 8% 22% 16% 2	1656
	21st to end	Night	52% 7% 11% 13% 16% 1	1620
May	1st to 10th	Night	45% 6% 10% 20% 17% 3	1620
	11th to 20th	Night	41% 5% 9% 22% 19% 3	1434
	21st to end	Night	34% 7% 15% 25% 17% 3	1551
June	1st to 10th	Night	42% 8% 11% 20% 18% 1	1383
	11th to 20th	Night	35% 7% 12% 25% 20% 1	1260
	21st to end	Night	39% 8% 13% 25% 13% 1	1260
July	1st to 10th	Night	28% 6% 13% 28% 23% 3	1225
	11th to 20th	Night	34% 8% 13% 30% 14% 1	1294
	21st to end	Night	34% 8% 13% 29% 15% 1	1641
August	1st to 10th	Night	32% 8% 18% 26% 15% 1	1600
	11th to 20th	Night	34% 8% 16% 25% 16% 1	1598
	21st to end	Night	41% 7% 15% 23% 12% 1	1813
September	1st to 10th	Night	35% 9% 15% 28% 13% 1	1800
	11th to 20th	Night	38% 9% 15% 26% 12%	1942
	21st to end	Night	46% 8% 13% 24% 8%	1989
October	1st to 10th	Night	53% 8% 10% 18% 11% 1	2160
	11th to 20th	Night	62% 8% 12% 14% 4	2160
	21st to end	Night	70% 7% 8% 10% 5%	2398
November	1st to 10th	Night	60% 8% 11% 16% 5%	2505
	11th to 20th	Night	68% 8% 12% 8% 3 1	2660
	21st to end	Night	76% 8% 9% 6% 1	2660
December	1st to 10th	Night	85% 7% 5% 3 1	2660
	11th to 20th	Night	77% 9% 8% 5% 1	3288
	21st to end	Night	86% 5% 4 4	5154

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	21% 20% 33% 18% 7% 2	180
	11th to 20th	Day	20% 18% 39% 17% 6%	244
	21st to end	Day	27% 9% 33% 25% 6%	297
February	1st to 10th	Day	24% 20% 35% 17% 4	270
	11th to 20th	Day	17% 16% 40% 23% 3 1	270
	21st to end	Day	21% 27% 32% 20%	225
March	1st to 10th	Day	19% 10% 40% 24% 6%	392
	11th to 20th	Day	18% 14% 33% 27% 7% 1	420
	21st to end	Day	26% 9% 30% 24% 10%	462
April	1st to 10th	Day	19% 12% 31% 27% 9% 1	420
	11th to 20th	Day	27% 8% 27% 20% 13% 5%	412
	21st to end	Day	25% 9% 26% 29% 8% 3	420
May	1st to 10th	Day	20% 7% 25% 31% 14% 3	423
	11th to 20th	Day	16% 4 23% 33% 18% 5%	447
	21st to end	Day	15% 3 22% 30% 23% 7%	485
June	1st to 10th	Day	16% 6% 20% 32% 24% 2	502
	11th to 20th	Day	13% 5% 21% 35% 20% 6%	630
	21st to end	Day	16% 4 20% 36% 20% 4	630
July	1st to 10th	Day	10% 3 16% 38% 27% 7%	621
	11th to 20th	Day	12% 4 20% 31% 25% 7%	538
	21st to end	Day	9% 4 18% 41% 23% 5%	488
August	1st to 10th	Day	13% 5% 15% 32% 25% 10%	446
	11th to 20th	Day	12% 5% 12% 32% 27% 12%	439
	21st to end	Day	14% 6% 23% 29% 21% 7%	495
September	1st to 10th	Day	13% 6% 23% 28% 21% 8%	450
	11th to 20th	Day	13% 4 22% 25% 25% 11%	450
	21st to end	Day	18% 8% 23% 24% 21% 6%	450
October	1st to 10th	Day	22% 11% 22% 23% 17% 4	450
	11th to 20th	Day	24% 18% 26% 24% 6% 1	450
	21st to end	Day	37% 16% 24% 17% 6%	470
November	1st to 10th	Day	23% 21% 24% 24% 8%	221
	11th to 20th	Day	23% 22% 32% 19% 3 1	180
	21st to end	Day	29% 18% 40% 12% 1	180
December	1st to 10th	Day	24% 23% 32% 17% 3	180
	11th to 20th	Day	30% 29% 24% 12% 4	180
	21st to end	Day	33% 19% 36% 10% 3	198
January	1st to 10th	Night	26% 21% 30% 16% 6% 1	950
	11th to 20th	Night	28% 18% 30% 19% 4 1	795
	21st to end	Night	21% 12% 34% 25% 8% 1	836
February	1st to 10th	Night	22% 18% 34% 21% 4	760
	11th to 20th	Night	20% 13% 36% 24% 6%	743
	21st to end	Night	23% 15% 33% 24% 6%	628
March	1st to 10th	Night	20% 11% 35% 26% 7%	723
	11th to 20th	Night	18% 12% 37% 25% 7% 1	720
	21st to end	Night	22% 8% 27% 30% 13% 1	792
April	1st to 10th	Night	25% 10% 28% 30% 7% 1	720
	11th to 20th	Night	21% 9% 28% 26% 14% 2	592
	21st to end	Night	22% 8% 26% 29% 15%	540
May	1st to 10th	Night	19% 4 19% 39% 18% 2	540
	11th to 20th	Night	17% 3 24% 38% 15% 3	372
	21st to end	Night	12% 2 19% 40% 25% 2	389
June	1st to 10th	Night	14% 5% 20% 41% 17% 3	360
	11th to 20th	Night	14% 4 17% 39% 24% 2	360
	21st to end	Night	16% 3 19% 35% 25% 2	360
July	1st to 10th	Night	11% 3 11% 42% 31% 3	350
	11th to 20th	Night	10% 3 20% 32% 31% 4	348
	21st to end	Night	9% 2 19% 39% 28% 2	558
August	1st to 10th	Night	12% 4 15% 34% 30% 6%	537
	11th to 20th	Night	11% 4 15% 32% 31% 6%	534
	21st to end	Night	16% 5% 21% 26% 28% 4	625
September	1st to 10th	Night	13% 6% 20% 30% 23% 8%	720
	11th to 20th	Night	17% 5% 18% 32% 23% 6%	720
	21st to end	Night	19% 9% 18% 31% 17% 6%	720
October	1st to 10th	Night	25% 8% 26% 24% 14% 2	720
	11th to 20th	Night	31% 14% 24% 23% 7% 2	720
	21st to end	Night	39% 14% 25% 18% 5%	792
November	1st to 10th	Night	29% 15% 27% 20% 9% 1	740
	11th to 20th	Night	28% 20% 30% 15% 6%	760
	21st to end	Night	35% 16% 28% 16% 4	760
December	1st to 10th	Night	35% 22% 26% 13% 3	760
	11th to 20th	Night	26% 23% 34% 13% 3 1	760
	21st to end	Night	32% 19% 32% 16% 2	1002

Page generated at 2024-02-27 06:30:18. Version ac07

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