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 2024-02-25.

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 7% 6% 3 4 4 5% 7% 34%	78090
	Night	17% 13% 5% 9% 6% 3 4 4 5% 6% 28%	81214
Transparency	Day	50% 6% 13% 20% 10% 1	77792
	Night	57% 6% 11% 17% 8% 1	81047
Seeing	Day	19% 11% 30% 26% 11% 2	14266
	Night	21% 12% 28% 25% 11% 2	23747

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% 12% 6% 3 3 3 3 4 15%	2222
	11th to 20th	Day	13% 17% 9% 17% 15% 4 5% 5% 4 4 8%	2530
	21st to end	Day	18% 18% 8% 12% 8% 4 5% 4 4 5% 13%	2981
February	1st to 10th	Day	13% 15% 6% 14% 10% 4 4 5% 4 6% 19%	1710
	11th to 20th	Day	12% 13% 5% 11% 8% 4 5% 6% 6% 5% 26%	1663
	21st to end	Day	13% 12% 6% 9% 8% 3 4 5% 5% 7% 28%	1505
March	1st to 10th	Day	13% 9% 4 7% 6% 4 5% 5% 5% 6% 38%	1877
	11th to 20th	Day	12% 9% 5% 7% 7% 4 6% 4 4 6% 36%	1980
	21st to end	Day	15% 8% 3 6% 5% 3 4 5% 6% 5% 40%	2178
April	1st to 10th	Day	19% 9% 4 6% 5% 3 5% 4 6% 7% 34%	2104
	11th to 20th	Day	19% 6% 3 6% 5% 3 4 4 4 7% 40%	2312
	21st to end	Day	19% 8% 3 6% 4 3 3 4 4 8% 38%	2340
May	1st to 10th	Day	18% 6% 2 5% 5% 3 4 4 6% 7% 41%	2340
	11th to 20th	Day	17% 5% 3 5% 5% 3 3 4 5% 8% 42%	2384
	21st to end	Day	12% 5% 2 5% 7% 3 5% 4 6% 8% 44%	2795
June	1st to 10th	Day	13% 6% 2 5% 6% 3 5% 5% 6% 7% 41%	2700
	11th to 20th	Day	11% 6% 2 6% 4 3 5% 5% 6% 8% 43%	2700
	21st to end	Day	13% 6% 3 5% 5% 4 5% 5% 6% 8% 41%	2700
July	1st to 10th	Day	7% 5% 3 5% 5% 3 4 4 6% 9% 50%	2700
	11th to 20th	Day	9% 4 3 5% 5% 3 5% 5% 6% 8% 46%	2647
	21st to end	Day	8% 5% 2 4 4 2 5% 5% 5% 8% 50%	2643
August	1st to 10th	Day	11% 4 2 4 4 3 5% 4 5% 9% 49%	2327
	11th to 20th	Day	9% 4 2 4 5% 3 4 5% 6% 8% 50%	2303
	21st to end	Day	11% 5% 3 4 6% 3 5% 5% 6% 8% 44%	2574
September	1st to 10th	Day	12% 5% 2 5% 6% 4 4 5% 5% 7% 45%	2128
	11th to 20th	Day	13% 4 2 4 5% 3 4 4 5% 8% 49%	1980
	21st to end	Day	17% 6% 2 6% 5% 3 5% 4 5% 7% 38%	1980
October	1st to 10th	Day	19% 7% 3 6% 6% 4 4 5% 5% 6% 36%	1850
	11th to 20th	Day	26% 9% 3 7% 6% 4 5% 4 5% 5% 26%	1800
	21st to end	Day	25% 14% 4 7% 7% 4 3 4 5% 5% 22%	1850
November	1st to 10th	Day	18% 15% 4 7% 6% 3 5% 6% 5% 6% 26%	1648
	11th to 20th	Day	18% 18% 6% 8% 5% 4 5% 4 7% 6% 19%	1520
	21st to end	Day	26% 20% 5% 8% 7% 3 4 5% 5% 5% 13%	1520
December	1st to 10th	Day	17% 24% 10% 10% 8% 3 4 4 3 4 12%	1497
	11th to 20th	Day	21% 21% 7% 13% 7% 3 4 3 3 4 15%	1671
	21st to end	Day	28% 23% 7% 12% 7% 3 3 3 4 3 7%	2431
January	1st to 10th	Night	17% 23% 11% 12% 7% 3 4 4 4 3 13%	4716
	11th to 20th	Night	13% 17% 8% 19% 11% 4 5% 4 4 4 11%	4440
	21st to end	Night	16% 19% 8% 11% 8% 4 5% 4 4 4 18%	4678
February	1st to 10th	Night	12% 16% 6% 14% 10% 4 4 4 4 5% 20%	2470
	11th to 20th	Night	11% 15% 5% 11% 9% 3 5% 5% 6% 5% 25%	2403
	21st to end	Night	15% 14% 7% 9% 6% 4 5% 4 5% 5% 27%	1844
March	1st to 10th	Night	13% 9% 4 7% 5% 4 4 5% 4 7% 38%	2070
	11th to 20th	Night	13% 11% 5% 7% 6% 3 4 5% 4 5% 36%	1979
	21st to end	Night	14% 9% 3 6% 5% 3 4 5% 5% 7% 38%	2178
April	1st to 10th	Night	22% 8% 3 6% 4 3 4 4 5% 5% 36%	1869
	11th to 20th	Night	18% 7% 2 5% 4 3 4 4 6% 8% 39%	1597
	21st to end	Night	19% 8% 4 8% 5% 2 4 4 6% 6% 34%	1620
May	1st to 10th	Night	14% 6% 3 6% 7% 5% 6% 5% 5% 6% 37%	1620
	11th to 20th	Night	15% 6% 3 5% 6% 3 5% 5% 5% 6% 40%	1507
	21st to end	Night	11% 6% 3 6% 5% 3 5% 5% 5% 7% 45%	1477
June	1st to 10th	Night	12% 6% 3 6% 5% 3 5% 6% 7% 6% 41%	1260
	11th to 20th	Night	10% 6% 2 4 4 3 6% 7% 7% 9% 43%	1260
	21st to end	Night	12% 6% 2 6% 5% 4 6% 5% 5% 8% 42%	1260
July	1st to 10th	Night	8% 2 2 5% 5% 2 4 3 4 9% 55%	1260
	11th to 20th	Night	8% 3 3 5% 6% 4 4 6% 7% 8% 46%	1309
	21st to end	Night	9% 3 2 5% 5% 4 4 5% 4 7% 51%	1673
August	1st to 10th	Night	8% 5% 1 4 4 3 5% 5% 7% 8% 50%	1611
	11th to 20th	Night	9% 4 2 5% 4 3 4 6% 6% 8% 48%	1598
	21st to end	Night	12% 5% 2 5% 5% 3 3 5% 5% 8% 45%	1782
September	1st to 10th	Night	12% 4 2 6% 5% 3 5% 4 5% 7% 47%	1811
	11th to 20th	Night	12% 4 2 5% 4 3 5% 4 5% 7% 48%	1980
	21st to end	Night	17% 7% 3 5% 6% 3 4 5% 5% 8% 38%	1980
October	1st to 10th	Night	22% 8% 3 6% 6% 3 4 4 4 7% 33%	2110
	11th to 20th	Night	26% 11% 4 7% 6% 4 4 4 4 7% 24%	2160
	21st to end	Night	27% 12% 5% 7% 7% 3 4 4 5% 6% 21%	2502
November	1st to 10th	Night	20% 15% 4 7% 5% 3 4 4 5% 6% 27%	2429
	11th to 20th	Night	19% 19% 6% 10% 7% 4 5% 4 4 6% 18%	2660
	21st to end	Night	24% 21% 6% 9% 6% 3 4 4 5% 4 15%	2660
December	1st to 10th	Night	22% 23% 9% 10% 7% 2 4 4 3 4 12%	2679
	11th to 20th	Night	20% 20% 7% 12% 6% 4 4 3 4 5% 15%	3526
	21st to end	Night	27% 21% 8% 12% 7% 3 4 3 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% 11% 19% 6%	1505
March	1st to 10th	Day	46% 6% 15% 18% 13% 2	1880
	11th to 20th	Day	49% 5% 12% 22% 9% 3	1980
	21st to end	Day	45% 5% 12% 21% 14% 3	2178
April	1st to 10th	Day	50% 6% 13% 19% 11% 1	2104
	11th to 20th	Day	45% 5% 9% 26% 14% 2	2312
	21st to end	Day	46% 4 12% 20% 13% 3	2340
May	1st to 10th	Day	43% 5% 10% 25% 14% 3	2340
	11th to 20th	Day	40% 6% 9% 25% 18% 1	2388
	21st to end	Day	38% 5% 17% 22% 16% 2	2795
June	1st to 10th	Day	39% 7% 11% 27% 14% 2	2700
	11th to 20th	Day	37% 5% 12% 27% 17% 2	2700
	21st to end	Day	41% 7% 12% 26% 13% 2	2700
July	1st to 10th	Day	30% 6% 15% 29% 19% 2	2626
	11th to 20th	Day	34% 8% 15% 29% 13% 1	2566
	21st to end	Day	31% 7% 15% 30% 16% 1	2496
August	1st to 10th	Day	32% 7% 18% 29% 13% 1	2314
	11th to 20th	Day	31% 8% 18% 31% 12%	2303
	21st to end	Day	37% 8% 16% 27% 11% 1	2574
September	1st to 10th	Day	38% 7% 14% 30% 11% 1	2128
	11th to 20th	Day	35% 6% 17% 32% 10% 1	1980
	21st to end	Day	44% 9% 15% 24% 8%	1980
October	1st to 10th	Day	50% 7% 11% 20% 12%	1850
	11th to 20th	Day	59% 6% 14% 15% 6%	1800
	21st to end	Day	64% 5% 12% 13% 5%	1850
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	59% 5% 13% 14% 9%	1844
March	1st to 10th	Night	47% 5% 14% 21% 12% 2	2080
	11th to 20th	Night	49% 5% 10% 22% 12% 2	1980
	21st to end	Night	45% 5% 11% 20% 16% 3	2178
April	1st to 10th	Night	50% 4 10% 20% 14% 2	1869
	11th to 20th	Night	43% 5% 8% 24% 19% 2	1597
	21st to end	Night	51% 5% 8% 17% 16% 3	1620
May	1st to 10th	Night	47% 5% 10% 21% 14% 3	1620
	11th to 20th	Night	43% 6% 8% 22% 18% 3	1508
	21st to end	Night	38% 6% 14% 22% 15% 4	1478
June	1st to 10th	Night	40% 7% 8% 24% 18% 3	1260
	11th to 20th	Night	35% 6% 13% 24% 20% 2	1260
	21st to end	Night	42% 4 14% 24% 14% 2	1260
July	1st to 10th	Night	27% 5% 13% 29% 22% 4	1225
	11th to 20th	Night	32% 7% 12% 30% 17% 1	1267
	21st to end	Night	34% 6% 13% 27% 18% 1	1580
August	1st to 10th	Night	30% 8% 19% 29% 13% 2	1600
	11th to 20th	Night	32% 7% 17% 29% 14% 1	1598
	21st to end	Night	37% 6% 17% 26% 12% 2	1782
September	1st to 10th	Night	36% 5% 14% 29% 14% 2	1811
	11th to 20th	Night	36% 6% 15% 33% 9%	1980
	21st to end	Night	44% 7% 16% 25% 8%	1980
October	1st to 10th	Night	53% 5% 11% 21% 11%	2110
	11th to 20th	Night	61% 5% 12% 17% 5%	2160
	21st to end	Night	64% 5% 11% 14% 5%	2502
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% 37% 10% 1	210
March	1st to 10th	Day	22% 16% 37% 19% 5% 1	320
	11th to 20th	Day	19% 15% 36% 22% 7% 1	420
	21st to end	Day	24% 14% 31% 23% 6% 1	462
April	1st to 10th	Day	22% 13% 32% 24% 9%	420
	11th to 20th	Day	25% 15% 27% 19% 11% 3	412
	21st to end	Day	25% 14% 35% 18% 8% 1	420
May	1st to 10th	Day	22% 7% 35% 26% 8% 2	423
	11th to 20th	Day	18% 8% 31% 28% 12% 3	447
	21st to end	Day	13% 6% 33% 29% 15% 4	555
June	1st to 10th	Day	14% 6% 35% 31% 13% 1	630
	11th to 20th	Day	13% 7% 30% 33% 14% 2	630
	21st to end	Day	16% 7% 29% 33% 13% 2	630
July	1st to 10th	Day	8% 4 27% 40% 19% 2	621
	11th to 20th	Day	10% 6% 26% 37% 16% 5%	618
	21st to end	Day	11% 3 28% 38% 16% 4	584
August	1st to 10th	Day	14% 5% 22% 34% 20% 4	446
	11th to 20th	Day	11% 5% 19% 36% 19% 10%	439
	21st to end	Day	13% 8% 26% 31% 18% 4	495
September	1st to 10th	Day	13% 8% 29% 26% 18% 5%	450
	11th to 20th	Day	11% 9% 26% 30% 19% 6%	450
	21st to end	Day	19% 11% 23% 29% 14% 4	450
October	1st to 10th	Day	22% 16% 24% 25% 12% 2	450
	11th to 20th	Day	26% 17% 35% 17% 5% 1	450
	21st to end	Day	29% 20% 34% 13% 3 1	365
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% 36% 21% 5%	611
March	1st to 10th	Night	18% 14% 38% 23% 7% 1	720
	11th to 20th	Night	19% 14% 34% 22% 10% 2	720
	21st to end	Night	19% 10% 30% 30% 10% 1	792
April	1st to 10th	Night	25% 11% 33% 25% 6% 1	672
	11th to 20th	Night	22% 10% 29% 26% 11% 3	533
	21st to end	Night	22% 8% 30% 26% 13% 1	540
May	1st to 10th	Night	16% 5% 26% 36% 13% 4	540
	11th to 20th	Night	17% 6% 25% 33% 17% 1	446
	21st to end	Night	15% 3 25% 34% 20% 3	389
June	1st to 10th	Night	14% 3 33% 34% 15% 2	360
	11th to 20th	Night	11% 8% 21% 38% 19% 2	360
	21st to end	Night	14% 4 19% 36% 25% 3	360
July	1st to 10th	Night	9% 3 19% 41% 23% 4	350
	11th to 20th	Night	9% 3 18% 39% 24% 6%	397
	21st to end	Night	9% 4 23% 34% 27% 4	591
August	1st to 10th	Night	10% 3 20% 38% 25% 5%	537
	11th to 20th	Night	11% 3 17% 31% 31% 7%	534
	21st to end	Night	12% 4 23% 31% 24% 6%	594
September	1st to 10th	Night	13% 7% 25% 28% 20% 8%	675
	11th to 20th	Night	13% 6% 25% 32% 16% 8%	720
	21st to end	Night	18% 9% 23% 26% 19% 5%	720
October	1st to 10th	Night	22% 10% 24% 28% 14% 2	720
	11th to 20th	Night	30% 13% 26% 20% 10% 1	720
	21st to end	Night	31% 15% 29% 20% 5% 1	792
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 2024-02-22 06:05:48. Version ac07

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