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 2024-11-01.

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% 10% 4 9% 5% 4 4 3 5% 6% 34%	101703
	Night	17% 14% 5% 11% 6% 4 4 3 4 5% 27%	97248
Transparency	Day	49% 9% 12% 19% 10% 1	101459
	Night	57% 8% 10% 16% 8% 1	97112
Seeing	Day	19% 10% 25% 27% 15% 4	15030
	Night	22% 12% 26% 25% 13% 2	24077

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% 23% 13% 15% 10% 4 3 3 2 3 6%	2208
	11th to 20th	Day	12% 19% 9% 27% 12% 7% 3 2 3 2 3	2681
	21st to end	Day	16% 22% 7% 17% 8% 5% 5% 3 3 3 9%	3124
February	1st to 10th	Day	13% 17% 6% 20% 10% 7% 4 2 4 4 13%	1710
	11th to 20th	Day	13% 16% 6% 16% 8% 6% 5% 3 4 5% 17%	1663
	21st to end	Day	15% 17% 6% 13% 6% 7% 4 3 5% 4 20%	1475
March	1st to 10th	Day	19% 11% 4 8% 7% 4 4 3 5% 4 32%	3392
	11th to 20th	Day	12% 15% 5% 11% 6% 5% 5% 3 5% 5% 28%	3480
	21st to end	Day	14% 9% 4 10% 5% 5% 4 4 5% 7% 34%	3815
April	1st to 10th	Day	19% 10% 3 8% 5% 5% 4 3 5% 6% 32%	2220
	11th to 20th	Day	20% 9% 2 5% 4 4 4 3 4 6% 39%	2396
	21st to end	Day	20% 9% 2 7% 4 3 4 2 4 7% 37%	2470
May	1st to 10th	Day	17% 7% 3 6% 5% 4 3 3 5% 7% 40%	4108
	11th to 20th	Day	13% 7% 3 7% 5% 5% 4 3 6% 6% 40%	4366
	21st to end	Day	14% 6% 2 6% 4 4 4 3 5% 7% 45%	4837
June	1st to 10th	Day	15% 6% 2 6% 4 4 5% 4 6% 7% 41%	2715
	11th to 20th	Day	11% 6% 2 5% 4 4 4 4 6% 8% 46%	2850
	21st to end	Day	14% 6% 2 5% 3 4 4 4 6% 7% 43%	2850
July	1st to 10th	Day	13% 5% 2 6% 5% 4 5% 4 6% 9% 41%	4760
	11th to 20th	Day	12% 5% 2 4 3 3 3 3 5% 7% 53%	4610
	21st to end	Day	8% 5% 2 5% 4 4 4 4 5% 7% 53%	4510
August	1st to 10th	Day	13% 6% 2 5% 4 4 4 4 6% 8% 44%	4104
	11th to 20th	Day	15% 6% 2 6% 4 4 4 4 6% 8% 43%	4044
	21st to end	Day	10% 4 3 5% 4 4 4 4 6% 8% 48%	4441
September	1st to 10th	Day	15% 6% 2 6% 5% 5% 4 4 4 7% 43%	2280
	11th to 20th	Day	14% 5% 3 5% 4 4 4 3 5% 7% 47%	2127
	21st to end	Day	18% 6% 2 8% 5% 5% 5% 3 4 6% 37%	2078
October	1st to 10th	Day	21% 8% 2 7% 4 5% 4 4 4 7% 35%	1900
	11th to 20th	Day	24% 12% 3 9% 6% 4 5% 3 4 6% 24%	1900
	21st to end	Day	32% 15% 3 10% 4 3 4 3 4 4 18%	2063
November	1st to 10th	Day	20% 17% 4 9% 5% 5% 4 3 4 6% 22%	1571
	11th to 20th	Day	19% 23% 6% 12% 5% 5% 4 3 4 5% 16%	1520
	21st to end	Day	23% 27% 6% 12% 5% 4 4 3 3 4 9%	1520
December	1st to 10th	Day	19% 30% 9% 17% 6% 3 3 2 3 3 5%	1520
	11th to 20th	Day	21% 22% 8% 20% 6% 5% 3 2 4 3 7%	1906
	21st to end	Day	25% 22% 8% 17% 6% 5% 3 2 3 2 7%	2489
January	1st to 10th	Night	18% 27% 11% 17% 9% 4 3 2 2 2 5%	4748
	11th to 20th	Night	15% 19% 8% 22% 11% 6% 5% 3 3 3 5%	4273
	21st to end	Night	18% 20% 8% 17% 10% 6% 5% 2 3 3 7%	4532
February	1st to 10th	Night	15% 18% 8% 18% 8% 5% 4 3 4 4 13%	2470
	11th to 20th	Night	13% 18% 7% 18% 6% 5% 5% 2 4 4 18%	2403
	21st to end	Night	18% 13% 5% 14% 7% 5% 5% 4 4 4 22%	1975
March	1st to 10th	Night	16% 12% 4 8% 5% 4 4 3 5% 7% 32%	3447
	11th to 20th	Night	12% 15% 5% 10% 5% 4 4 3 4 6% 32%	3479
	21st to end	Night	14% 11% 5% 14% 5% 4 4 3 4 5% 29%	3817
April	1st to 10th	Night	21% 11% 3 8% 6% 4 4 3 5% 5% 31%	1958
	11th to 20th	Night	20% 9% 3 6% 4 5% 4 2 5% 7% 36%	1749
	21st to end	Night	19% 9% 4 9% 5% 4 5% 3 5% 6% 32%	1710
May	1st to 10th	Night	15% 7% 3 6% 6% 4 4 4 5% 7% 39%	2833
	11th to 20th	Night	16% 6% 3 7% 4 5% 4 3 6% 7% 38%	2527
	21st to end	Night	10% 6% 3 6% 5% 4 4 3 5% 7% 46%	2738
June	1st to 10th	Night	15% 6% 2 7% 5% 5% 4 4 6% 8% 38%	1459
	11th to 20th	Night	10% 5% 2 4 5% 4 6% 5% 7% 9% 43%	1330
	21st to end	Night	13% 8% 2 7% 5% 5% 3 4 6% 7% 41%	1330
July	1st to 10th	Night	11% 6% 3 8% 4 4 3 4 5% 7% 46%	2210
	11th to 20th	Night	14% 4 1 5% 3 3 4 3 5% 6% 51%	2351
	21st to end	Night	9% 4 1 6% 3 4 5% 3 6% 8% 50%	3040
August	1st to 10th	Night	12% 5% 2 6% 4 5% 5% 4 6% 7% 45%	2825
	11th to 20th	Night	16% 6% 3 6% 4 3 4 3 5% 7% 43%	2785
	21st to end	Night	15% 5% 2 6% 4 3 4 3 4 7% 47%	3183
September	1st to 10th	Night	13% 6% 2 5% 4 3 4 3 7% 8% 44%	1900
	11th to 20th	Night	16% 5% 2 5% 4 3 4 3 5% 8% 45%	2050
	21st to end	Night	21% 6% 3 6% 5% 4 4 3 5% 6% 38%	2100
October	1st to 10th	Night	22% 8% 2 8% 5% 5% 4 3 4 5% 34%	2280
	11th to 20th	Night	26% 12% 3 9% 5% 5% 4 3 4 6% 24%	2280
	21st to end	Night	31% 16% 4 7% 4 4 3 3 5% 4 18%	2532
November	1st to 10th	Night	22% 16% 4 8% 5% 4 4 3 4 5% 25%	2512
	11th to 20th	Night	20% 24% 6% 11% 5% 4 3 4 4 5% 17%	2660
	21st to end	Night	24% 27% 7% 10% 4 4 4 2 3 3 11%	2660
December	1st to 10th	Night	22% 32% 9% 13% 5% 3 3 2 2 2 7%	2660
	11th to 20th	Night	19% 24% 8% 18% 5% 4 4 2 3 4 10%	3288
	21st to end	Night	26% 24% 10% 16% 5% 4 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	53% 10% 14% 13% 9%	3395
	11th to 20th	Day	55% 9% 12% 17% 5% 1	3480
	21st to end	Day	46% 9% 14% 19% 10% 1	3815
April	1st to 10th	Day	53% 6% 11% 20% 10% 1	2220
	11th to 20th	Day	47% 6% 9% 23% 14% 1	2396
	21st to end	Day	48% 6% 12% 19% 12% 3	2470
May	1st to 10th	Day	42% 8% 12% 21% 15% 2	4120
	11th to 20th	Day	38% 12% 15% 22% 12% 1	4370
	21st to end	Day	36% 9% 13% 20% 19% 3	4837
June	1st to 10th	Day	40% 9% 12% 23% 15% 1	2715
	11th to 20th	Day	35% 7% 13% 25% 17% 1	2850
	21st to end	Day	39% 9% 14% 23% 14% 1	2850
July	1st to 10th	Day	38% 8% 17% 22% 13% 1	4686
	11th to 20th	Day	30% 7% 14% 35% 12% 1	4529
	21st to end	Day	31% 8% 12% 29% 19% 1	4366
August	1st to 10th	Day	36% 8% 15% 26% 13% 1	4091
	11th to 20th	Day	38% 8% 18% 24% 11%	4083
	21st to end	Day	32% 8% 14% 34% 11% 1	4441
September	1st to 10th	Day	41% 8% 15% 26% 11% 1	2280
	11th to 20th	Day	36% 8% 16% 27% 12%	2127
	21st to end	Day	47% 9% 12% 24% 8%	2078
October	1st to 10th	Day	49% 9% 13% 19% 10% 1	1900
	11th to 20th	Day	62% 8% 11% 14% 5% 1	1900
	21st to end	Day	69% 8% 10% 9% 4	2063
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	49% 10% 12% 19% 9% 1	3457
	11th to 20th	Night	50% 10% 14% 17% 8% 1	3480
	21st to end	Night	52% 10% 11% 16% 9% 1	3817
April	1st to 10th	Night	55% 6% 9% 19% 11% 1	1958
	11th to 20th	Night	49% 5% 7% 21% 15% 2	1749
	21st to end	Night	51% 7% 11% 13% 16% 1	1710
May	1st to 10th	Night	41% 9% 13% 20% 15% 2	2840
	11th to 20th	Night	40% 9% 13% 22% 14% 2	2528
	21st to end	Night	34% 8% 13% 24% 19% 2	2739
June	1st to 10th	Night	42% 9% 11% 19% 18% 1	1459
	11th to 20th	Night	35% 7% 12% 25% 20% 1	1330
	21st to end	Night	40% 8% 12% 25% 13% 1	1330
July	1st to 10th	Night	37% 7% 13% 23% 17% 3	2175
	11th to 20th	Night	34% 6% 12% 35% 13% 1	2309
	21st to end	Night	32% 7% 11% 30% 18% 1	2943
August	1st to 10th	Night	37% 7% 14% 26% 15% 1	2814
	11th to 20th	Night	39% 7% 18% 24% 12% 1	2812
	21st to end	Night	37% 6% 12% 31% 13% 1	3183
September	1st to 10th	Night	35% 8% 15% 28% 13% 1	1900
	11th to 20th	Night	37% 9% 14% 26% 14%	2050
	21st to end	Night	46% 8% 13% 24% 9%	2100
October	1st to 10th	Night	51% 8% 10% 19% 12% 1	2280
	11th to 20th	Night	60% 8% 12% 15% 5%	2280
	21st to end	Night	68% 7% 9% 11% 4	2532
November	1st to 10th	Night	60% 7% 11% 16% 5%	2512
	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	22% 27% 32% 20%	225
March	1st to 10th	Day	20% 11% 39% 24% 6%	431
	11th to 20th	Day	17% 15% 33% 27% 6% 1	460
	21st to end	Day	25% 10% 31% 24% 9%	506
April	1st to 10th	Day	19% 13% 31% 27% 9% 1	460
	11th to 20th	Day	28% 10% 27% 19% 12% 4	452
	21st to end	Day	25% 11% 26% 28% 8% 3	460
May	1st to 10th	Day	19% 7% 25% 32% 14% 3	463
	11th to 20th	Day	15% 5% 22% 34% 19% 5%	487
	21st to end	Day	14% 4 23% 30% 22% 7%	529
June	1st to 10th	Day	17% 6% 20% 31% 23% 2	545
	11th to 20th	Day	13% 5% 21% 37% 20% 5%	680
	21st to end	Day	18% 5% 20% 35% 19% 4	680
July	1st to 10th	Day	10% 3 16% 38% 26% 6%	671
	11th to 20th	Day	12% 5% 20% 31% 26% 7%	583
	21st to end	Day	9% 4 18% 39% 23% 6%	532
August	1st to 10th	Day	13% 5% 17% 32% 24% 9%	486
	11th to 20th	Day	13% 6% 12% 31% 26% 12%	479
	21st to end	Day	14% 6% 21% 29% 23% 7%	539
September	1st to 10th	Day	14% 7% 23% 27% 22% 9%	490
	11th to 20th	Day	12% 4 20% 23% 28% 13%	490
	21st to end	Day	18% 8% 22% 24% 22% 6%	490
October	1st to 10th	Day	21% 11% 23% 24% 16% 4	490
	11th to 20th	Day	23% 17% 27% 24% 7% 1	490
	21st to end	Day	36% 17% 24% 17% 6%	512
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	22% 15% 34% 24% 6%	628
March	1st to 10th	Night	20% 11% 36% 25% 7%	760
	11th to 20th	Night	18% 13% 37% 25% 7% 1	760
	21st to end	Night	21% 9% 27% 30% 12% 1	836
April	1st to 10th	Night	25% 10% 29% 30% 6% 1	760
	11th to 20th	Night	22% 9% 28% 26% 13% 1	625
	21st to end	Night	22% 9% 26% 29% 15%	570
May	1st to 10th	Night	18% 4 19% 39% 18% 2	570
	11th to 20th	Night	17% 3 23% 38% 16% 3	393
	21st to end	Night	12% 2 19% 40% 25% 2	411
June	1st to 10th	Night	15% 6% 20% 41% 17% 2	380
	11th to 20th	Night	13% 4 18% 38% 24% 2	380
	21st to end	Night	17% 4 19% 34% 24% 2	380
July	1st to 10th	Night	10% 3 11% 43% 31% 2	370
	11th to 20th	Night	10% 4 20% 32% 31% 4	368
	21st to end	Night	9% 2 19% 38% 30% 2	590
August	1st to 10th	Night	11% 4 15% 34% 29% 6%	567
	11th to 20th	Night	12% 4 16% 31% 31% 6%	564
	21st to end	Night	17% 5% 21% 26% 28% 3	660
September	1st to 10th	Night	13% 6% 21% 30% 22% 7%	760
	11th to 20th	Night	16% 5% 17% 31% 25% 6%	760
	21st to end	Night	19% 9% 18% 31% 17% 6%	760
October	1st to 10th	Night	25% 9% 27% 24% 14% 2	760
	11th to 20th	Night	30% 14% 24% 23% 8% 2	760
	21st to end	Night	37% 14% 26% 17% 5%	836
November	1st to 10th	Night	29% 16% 27% 20% 9% 1	743
	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 2024-10-29 11:20:52. Version ac07

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