Chi'Cheemaun 2/3rds Point
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Chi'Cheemaun 2/3rds Point clear sky chart from 2005-11-06 to 2024-10-24.

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	15% 10% 4 8% 5% 4 4 3 5% 6% 36%	101393
	Night	16% 12% 4 10% 5% 4 4 3 5% 6% 31%	97421
Transparency	Day	48% 6% 13% 21% 11% 1	101145
	Night	54% 6% 11% 18% 9% 1	97288
Seeing	Day	19% 11% 30% 26% 12% 3	15283
	Night	21% 12% 28% 25% 12% 2	24502

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	19% 21% 12% 14% 5% 3 3 3 3 3 15%	2222
	11th to 20th	Day	12% 18% 8% 21% 11% 6% 4 4 4 4 8%	2530
	21st to end	Day	18% 19% 7% 14% 7% 6% 5% 3 4 5% 13%	2981
February	1st to 10th	Day	12% 16% 6% 16% 8% 5% 4 3 5% 6% 19%	1710
	11th to 20th	Day	12% 15% 5% 11% 7% 5% 4 5% 6% 4 26%	1663
	21st to end	Day	13% 14% 5% 11% 6% 4 5% 4 5% 6% 28%	1555
March	1st to 10th	Day	16% 12% 3 7% 4 4 4 4 5% 6% 35%	3267
	11th to 20th	Day	11% 13% 5% 10% 6% 5% 5% 4 5% 7% 30%	3480
	21st to end	Day	13% 9% 4 7% 5% 4 4 4 5% 6% 38%	3815
April	1st to 10th	Day	18% 10% 3 7% 4 4 4 3 6% 6% 34%	2222
	11th to 20th	Day	19% 7% 2 6% 5% 4 3 3 4 6% 40%	2442
	21st to end	Day	19% 8% 3 6% 4 4 3 3 5% 8% 38%	2470
May	1st to 10th	Day	17% 6% 2 8% 4 3 3 3 5% 6% 44%	4108
	11th to 20th	Day	14% 7% 3 7% 4 4 3 3 5% 7% 42%	4234
	21st to end	Day	14% 5% 2 7% 5% 4 4 3 5% 6% 45%	4963
June	1st to 10th	Day	13% 7% 2 6% 6% 5% 4 4 6% 7% 40%	2850
	11th to 20th	Day	11% 6% 2 6% 4 4 5% 4 6% 8% 43%	2850
	21st to end	Day	14% 6% 2 6% 4 5% 5% 4 6% 7% 40%	2850
July	1st to 10th	Day	13% 7% 4 9% 5% 5% 4 3 5% 7% 39%	4760
	11th to 20th	Day	9% 4 2 5% 4 4 4 3 6% 8% 51%	4665
	21st to end	Day	9% 5% 2 5% 4 3 4 3 5% 7% 54%	4632
August	1st to 10th	Day	10% 4 2 6% 4 5% 5% 4 6% 9% 45%	4104
	11th to 20th	Day	13% 5% 2 5% 4 3 3 3 6% 8% 47%	4044
	21st to end	Day	10% 4 2 6% 5% 5% 4 4 6% 8% 47%	4532
September	1st to 10th	Day	11% 6% 2 6% 5% 5% 4 3 5% 7% 46%	2245
	11th to 20th	Day	12% 4 2 5% 4 4 4 3 5% 8% 50%	2090
	21st to end	Day	17% 7% 2 7% 4 4 5% 3 5% 7% 40%	2090
October	1st to 10th	Day	18% 7% 2 7% 5% 5% 4 4 5% 5% 37%	1952
	11th to 20th	Day	24% 10% 3 8% 5% 6% 5% 3 5% 6% 27%	1900
	21st to end	Day	25% 14% 4 8% 6% 4 3 3 5% 5% 22%	1880
November	1st to 10th	Day	17% 15% 4 8% 6% 4 4 4 5% 6% 26%	1648
	11th to 20th	Day	17% 19% 6% 9% 4 6% 4 3 6% 6% 18%	1520
	21st to end	Day	26% 20% 6% 9% 6% 4 4 4 5% 5% 13%	1520
December	1st to 10th	Day	17% 26% 8% 11% 8% 5% 3 3 4 4 12%	1497
	11th to 20th	Day	21% 22% 7% 14% 6% 4 3 3 3 3 14%	1671
	21st to end	Day	28% 24% 6% 14% 5% 4 3 3 3 3 7%	2431
January	1st to 10th	Night	17% 24% 10% 14% 6% 4 4 3 4 3 13%	4716
	11th to 20th	Night	13% 18% 7% 22% 8% 5% 4 3 4 4 11%	4440
	21st to end	Night	16% 19% 7% 13% 7% 6% 4 3 4 4 18%	4678
February	1st to 10th	Night	12% 18% 6% 15% 8% 5% 4 3 5% 5% 20%	2470
	11th to 20th	Night	11% 16% 5% 11% 8% 4 5% 4 6% 5% 25%	2403
	21st to end	Night	15% 16% 5% 10% 5% 5% 5% 4 5% 5% 26%	1897
March	1st to 10th	Night	14% 8% 3 7% 4 5% 4 3 5% 6% 41%	3573
	11th to 20th	Night	9% 12% 4 8% 5% 4 5% 4 5% 6% 38%	3479
	21st to end	Night	12% 9% 5% 10% 5% 5% 4 4 5% 6% 35%	3817
April	1st to 10th	Night	21% 9% 3 6% 4 4 4 3 5% 5% 35%	1972
	11th to 20th	Night	19% 8% 2 5% 4 4 3 3 6% 8% 37%	1687
	21st to end	Night	19% 9% 4 9% 4 4 4 3 6% 5% 34%	1710
May	1st to 10th	Night	16% 6% 2 9% 5% 5% 5% 3 4 5% 40%	2833
	11th to 20th	Night	12% 6% 3 8% 6% 4 5% 3 5% 8% 41%	2657
	21st to end	Night	13% 7% 3 8% 5% 3 4 3 5% 6% 42%	2600
June	1st to 10th	Night	12% 7% 2 7% 5% 4 5% 5% 7% 6% 40%	1330
	11th to 20th	Night	10% 6% 2 4 4 4 6% 5% 7% 8% 44%	1330
	21st to end	Night	13% 6% 2 6% 5% 5% 5% 4 6% 6% 41%	1330
July	1st to 10th	Night	12% 5% 3 7% 5% 4 4 3 4 7% 47%	2210
	11th to 20th	Night	10% 4 2 5% 4 4 3 3 6% 8% 51%	2301
	21st to end	Night	9% 5% 2 6% 4 4 4 3 4 7% 52%	2924
August	1st to 10th	Night	8% 6% 2 6% 4 5% 4 4 7% 8% 46%	2825
	11th to 20th	Night	13% 5% 2 6% 4 4 4 4 6% 9% 44%	2785
	21st to end	Night	9% 5% 2 6% 4 4 4 4 5% 7% 49%	3124
September	1st to 10th	Night	12% 4 2 6% 4 4 4 3 5% 7% 47%	1913
	11th to 20th	Night	11% 5% 2 6% 3 4 4 4 5% 7% 50%	2090
	21st to end	Night	17% 7% 2 6% 5% 4 4 4 5% 7% 39%	2090
October	1st to 10th	Night	21% 8% 3 7% 5% 4 4 3 4 6% 35%	2228
	11th to 20th	Night	25% 11% 3 8% 5% 4 4 4 4 7% 25%	2280
	21st to end	Night	26% 13% 4 8% 6% 4 4 4 4 6% 22%	2539
November	1st to 10th	Night	20% 16% 3 8% 5% 4 4 3 5% 6% 27%	2429
	11th to 20th	Night	18% 20% 5% 10% 6% 5% 5% 3 4 6% 18%	2660
	21st to end	Night	23% 22% 6% 9% 5% 4 4 3 5% 4 15%	2660
December	1st to 10th	Night	22% 26% 7% 11% 6% 3 4 3 3 4 12%	2679
	11th to 20th	Night	20% 21% 6% 13% 6% 5% 4 3 4 5% 15%	3526
	21st to end	Night	26% 22% 7% 13% 5% 4 4 2 4 4 9%	5236

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	72% 9% 11% 7% 1	2223
	11th to 20th	Day	80% 6% 7% 5% 2	2530
	21st to end	Day	72% 8% 11% 7% 2	2981
February	1st to 10th	Day	65% 6% 11% 15% 3	1710
	11th to 20th	Day	58% 7% 14% 14% 6% 1	1672
	21st to end	Day	57% 7% 12% 19% 5%	1555
March	1st to 10th	Day	50% 7% 15% 16% 11% 1	3270
	11th to 20th	Day	53% 6% 12% 21% 7% 2	3480
	21st to end	Day	45% 8% 15% 16% 13% 4	3815
April	1st to 10th	Day	49% 6% 12% 20% 11% 1	2222
	11th to 20th	Day	45% 5% 8% 26% 14% 1	2442
	21st to end	Day	46% 4 12% 21% 14% 3	2470
May	1st to 10th	Day	41% 5% 10% 23% 18% 2	4120
	11th to 20th	Day	39% 6% 13% 26% 14% 1	4238
	21st to end	Day	39% 5% 13% 18% 22% 3	4963
June	1st to 10th	Day	40% 7% 11% 27% 13% 2	2850
	11th to 20th	Day	36% 5% 12% 27% 17% 2	2850
	21st to end	Day	42% 6% 12% 25% 13% 2	2850
July	1st to 10th	Day	43% 7% 13% 23% 13% 1	4686
	11th to 20th	Day	29% 7% 16% 34% 13% 1	4584
	21st to end	Day	29% 6% 11% 29% 23% 1	4485
August	1st to 10th	Day	33% 8% 15% 29% 13% 1	4091
	11th to 20th	Day	35% 6% 17% 29% 12%	4083
	21st to end	Day	34% 8% 14% 35% 10% 1	4531
September	1st to 10th	Day	38% 6% 14% 30% 11% 1	2245
	11th to 20th	Day	34% 6% 16% 32% 12% 1	2090
	21st to end	Day	44% 8% 15% 23% 10%	2090
October	1st to 10th	Day	48% 7% 11% 21% 13%	1952
	11th to 20th	Day	58% 5% 14% 16% 6%	1900
	21st to end	Day	63% 5% 12% 14% 5%	1880
November	1st to 10th	Day	57% 7% 13% 17% 6%	1648
	11th to 20th	Day	64% 5% 14% 11% 5%	1520
	21st to end	Day	73% 5% 12% 8% 2	1520
December	1st to 10th	Day	76% 5% 10% 6% 2	1497
	11th to 20th	Day	76% 4 8% 11% 1	1671
	21st to end	Day	83% 5% 7% 5% 1	2431
January	1st to 10th	Night	73% 6% 10% 7% 3 1	4716
	11th to 20th	Night	77% 6% 9% 6% 2	4440
	21st to end	Night	71% 6% 11% 9% 3	4678
February	1st to 10th	Night	66% 4 10% 15% 4	2470
	11th to 20th	Night	59% 6% 13% 16% 6% 1	2405
	21st to end	Night	58% 6% 13% 14% 8%	1897
March	1st to 10th	Night	43% 7% 17% 21% 12% 1	3583
	11th to 20th	Night	45% 5% 13% 24% 11% 2	3480
	21st to end	Night	46% 7% 12% 21% 12% 2	3817
April	1st to 10th	Night	50% 4 10% 20% 14% 2	1972
	11th to 20th	Night	44% 5% 8% 23% 18% 2	1687
	21st to end	Night	51% 5% 8% 17% 15% 3	1710
May	1st to 10th	Night	45% 5% 10% 23% 16% 2	2840
	11th to 20th	Night	40% 7% 10% 23% 18% 2	2658
	21st to end	Night	41% 6% 11% 20% 17% 5%	2601
June	1st to 10th	Night	41% 7% 8% 24% 18% 3	1330
	11th to 20th	Night	35% 6% 12% 24% 21% 2	1330
	21st to end	Night	43% 4 13% 24% 13% 2	1330
July	1st to 10th	Night	37% 6% 13% 24% 16% 4	2175
	11th to 20th	Night	30% 6% 10% 39% 14% 1	2259
	21st to end	Night	33% 5% 10% 25% 26% 1	2831
August	1st to 10th	Night	34% 7% 14% 30% 13% 1	2814
	11th to 20th	Night	35% 8% 17% 26% 14%	2812
	21st to end	Night	33% 6% 14% 32% 13% 1	3124
September	1st to 10th	Night	36% 5% 14% 29% 14% 2	1913
	11th to 20th	Night	34% 6% 14% 34% 11% 1	2090
	21st to end	Night	44% 6% 15% 24% 10%	2090
October	1st to 10th	Night	51% 5% 10% 22% 12%	2228
	11th to 20th	Night	60% 5% 12% 17% 6%	2280
	21st to end	Night	63% 5% 11% 15% 5%	2539
November	1st to 10th	Night	57% 6% 11% 20% 6%	2429
	11th to 20th	Night	67% 5% 13% 11% 4	2660
	21st to end	Night	71% 6% 12% 10% 2	2660
December	1st to 10th	Night	76% 5% 10% 7% 1	2679
	11th to 20th	Night	72% 5% 10% 9% 3 1	3525
	21st to end	Night	80% 5% 8% 5% 2	5236

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% 19% 31% 18% 5%	186
	11th to 20th	Day	21% 19% 35% 19% 6%	270
	21st to end	Day	30% 10% 32% 21% 8%	297
February	1st to 10th	Day	23% 24% 32% 16% 5%	270
	11th to 20th	Day	21% 22% 38% 17% 2	270
	21st to end	Day	25% 28% 38% 8% 1	225
March	1st to 10th	Day	22% 15% 38% 19% 5% 1	355
	11th to 20th	Day	19% 15% 35% 23% 7% 1	460
	21st to end	Day	22% 16% 31% 23% 6% 1	506
April	1st to 10th	Day	23% 13% 33% 23% 8%	460
	11th to 20th	Day	27% 15% 27% 18% 10% 2	452
	21st to end	Day	25% 13% 34% 17% 8% 1	460
May	1st to 10th	Day	22% 7% 36% 25% 8% 2	463
	11th to 20th	Day	18% 8% 31% 29% 12% 3	487
	21st to end	Day	14% 7% 32% 29% 15% 3	603
June	1st to 10th	Day	14% 7% 34% 31% 13% 1	680
	11th to 20th	Day	13% 7% 29% 34% 15% 2	680
	21st to end	Day	17% 7% 28% 33% 13% 2	680
July	1st to 10th	Day	9% 4 25% 41% 18% 2	671
	11th to 20th	Day	10% 5% 25% 37% 18% 4	668
	21st to end	Day	11% 3 26% 37% 18% 4	633
August	1st to 10th	Day	14% 5% 22% 34% 20% 4	486
	11th to 20th	Day	12% 5% 19% 35% 20% 9%	479
	21st to end	Day	13% 7% 24% 31% 20% 5%	539
September	1st to 10th	Day	12% 9% 28% 27% 20% 5%	490
	11th to 20th	Day	10% 9% 24% 28% 20% 9%	490
	21st to end	Day	19% 10% 22% 27% 17% 4	490
October	1st to 10th	Day	21% 15% 25% 25% 12% 2	490
	11th to 20th	Day	24% 16% 34% 19% 7% 1	490
	21st to end	Day	28% 20% 33% 14% 3 1	377
November	1st to 10th	Day	28% 17% 36% 14% 5%	258
	11th to 20th	Day	25% 21% 37% 14% 3	180
	21st to end	Day	35% 23% 31% 11% 1	180
December	1st to 10th	Day	27% 23% 31% 16% 4	180
	11th to 20th	Day	32% 23% 35% 8% 2	180
	21st to end	Day	34% 22% 36% 5% 4	198
January	1st to 10th	Night	24% 21% 29% 21% 4 1	950
	11th to 20th	Night	26% 17% 31% 21% 4 1	950
	21st to end	Night	22% 12% 34% 22% 8% 1	917
February	1st to 10th	Night	21% 19% 34% 22% 5%	760
	11th to 20th	Night	19% 15% 35% 25% 7%	743
	21st to end	Night	22% 15% 37% 21% 4	628
March	1st to 10th	Night	18% 15% 38% 22% 6% 1	760
	11th to 20th	Night	18% 14% 34% 23% 9% 1	760
	21st to end	Night	19% 12% 30% 29% 9% 1	836
April	1st to 10th	Night	25% 11% 34% 24% 6% 1	709
	11th to 20th	Night	23% 11% 29% 25% 10% 2	563
	21st to end	Night	22% 9% 29% 25% 14% 1	570
May	1st to 10th	Night	16% 6% 27% 35% 13% 4	570
	11th to 20th	Night	16% 6% 26% 34% 17% 1	471
	21st to end	Night	16% 4 25% 33% 20% 3	411
June	1st to 10th	Night	14% 4 32% 34% 14% 2	380
	11th to 20th	Night	11% 8% 21% 38% 20% 2	380
	21st to end	Night	14% 4 19% 36% 24% 2	380
July	1st to 10th	Night	10% 3 19% 41% 23% 4	370
	11th to 20th	Night	9% 3 18% 38% 26% 6%	420
	21st to end	Night	9% 4 22% 34% 28% 4	624
August	1st to 10th	Night	10% 3 19% 37% 25% 5%	567
	11th to 20th	Night	12% 3 16% 31% 32% 7%	564
	21st to end	Night	12% 3 22% 31% 25% 6%	627
September	1st to 10th	Night	13% 6% 25% 27% 21% 8%	713
	11th to 20th	Night	13% 5% 24% 30% 18% 11%	760
	21st to end	Night	18% 9% 22% 26% 20% 5%	760
October	1st to 10th	Night	21% 10% 26% 28% 13% 2	760
	11th to 20th	Night	29% 13% 26% 20% 11% 1	760
	21st to end	Night	30% 15% 29% 20% 5% 1	805
November	1st to 10th	Night	27% 14% 28% 21% 8% 1	740
	11th to 20th	Night	26% 22% 28% 17% 7%	760
	21st to end	Night	31% 17% 29% 17% 5%	760
December	1st to 10th	Night	32% 21% 29% 12% 6%	779
	11th to 20th	Night	30% 21% 33% 12% 3 1	950
	21st to end	Night	35% 15% 31% 15% 4	1045

Page generated at 2024-10-21 02:20:00. Version ac07

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