Canaan
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Canaan clear sky chart from 2005-11-06 to 2026-06-01.

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% 13% 5% 11% 6% 5% 5% 4 5% 6% 24%	131951
	Night	15% 14% 5% 13% 7% 6% 5% 3 4 5% 23%	131222
Transparency	Day	59% 5% 10% 16% 8% 1	135432
	Night	63% 5% 10% 14% 7% 1	135828
Seeing	Day	28% 20% 28% 16% 6% 2	16684
	Night	26% 18% 26% 22% 8% 1	25603

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	10% 14% 11% 20% 11% 10% 5% 3 3 3 10%	4661
	11th to 20th	Day	6% 17% 8% 23% 16% 7% 3 2 4 3 10%	4650
	21st to end	Day	7% 13% 8% 15% 9% 13% 8% 3 4 5% 16%	5124
February	1st to 10th	Day	12% 15% 7% 16% 10% 7% 6% 3 3 4 17%	1778
	11th to 20th	Day	9% 16% 9% 18% 10% 7% 5% 3 3 4 16%	2048
	21st to end	Day	10% 17% 6% 16% 9% 6% 5% 3 4 4 20%	1730
March	1st to 10th	Day	17% 16% 6% 16% 7% 5% 4 2 3 3 19%	4576
	11th to 20th	Day	13% 17% 6% 12% 6% 4 4 3 4 5% 27%	4844
	21st to end	Day	18% 15% 6% 14% 6% 4 3 2 4 5% 23%	5956
April	1st to 10th	Day	18% 20% 5% 11% 5% 3 3 2 3 5% 25%	2520
	11th to 20th	Day	16% 17% 4 9% 4 4 4 3 4 4 30%	2550
	21st to end	Day	21% 15% 3 9% 4 4 4 3 4 5% 27%	2730
May	1st to 10th	Day	28% 15% 4 9% 5% 4 4 3 4 4 19%	6016
	11th to 20th	Day	18% 11% 3 10% 6% 5% 5% 4 5% 7% 26%	6450
	21st to end	Day	19% 9% 3 7% 5% 5% 6% 5% 7% 8% 26%	7103
June	1st to 10th	Day	26% 10% 3 7% 5% 5% 5% 4 5% 7% 23%	2800
	11th to 20th	Day	18% 8% 3 7% 6% 4 5% 5% 6% 8% 31%	2800
	21st to end	Day	22% 9% 3 8% 6% 5% 5% 4 7% 6% 25%	2800
July	1st to 10th	Day	16% 7% 3 9% 6% 6% 6% 6% 9% 9% 24%	6360
	11th to 20th	Day	13% 7% 3 8% 5% 5% 6% 5% 8% 9% 31%	6360
	21st to end	Day	15% 8% 3 7% 5% 4 5% 4 6% 9% 37%	6926
August	1st to 10th	Day	17% 8% 3 9% 6% 6% 6% 4 6% 8% 26%	4467
	11th to 20th	Day	16% 9% 3 9% 6% 6% 6% 5% 7% 9% 23%	4175
	21st to end	Day	17% 8% 2 7% 5% 5% 4 4 6% 8% 35%	4359
September	1st to 10th	Day	16% 7% 2 6% 5% 4 4 4 5% 7% 39%	2400
	11th to 20th	Day	17% 8% 2 5% 4 3 5% 3 5% 7% 42%	2221
	21st to end	Day	17% 10% 2 7% 5% 4 4 5% 6% 8% 33%	2200
October	1st to 10th	Day	21% 12% 4 6% 4 4 4 4 5% 5% 30%	2200
	11th to 20th	Day	16% 16% 4 9% 5% 3 4 4 6% 6% 27%	1873
	21st to end	Day	21% 23% 5% 8% 4 4 3 2 3 4 23%	1980
November	1st to 10th	Day	15% 20% 5% 9% 5% 5% 4 3 3 5% 26%	1851
	11th to 20th	Day	15% 20% 7% 12% 6% 3 4 3 4 4 21%	1890
	21st to end	Day	17% 17% 7% 15% 6% 4 6% 2 4 4 18%	1759
December	1st to 10th	Day	10% 20% 9% 24% 11% 4 3 2 3 3 10%	2680
	11th to 20th	Day	13% 18% 9% 16% 6% 5% 4 2 4 3 19%	3066
	21st to end	Day	16% 18% 6% 16% 6% 4 6% 2 4 4 18%	4048
January	1st to 10th	Night	8% 16% 10% 22% 12% 8% 5% 3 3 3 10%	8234
	11th to 20th	Night	8% 16% 9% 21% 16% 7% 6% 3 3 3 8%	8235
	21st to end	Night	7% 13% 6% 14% 10% 14% 8% 4 5% 4 15%	9057
February	1st to 10th	Night	10% 15% 6% 17% 11% 8% 6% 3 4 4 16%	2840
	11th to 20th	Night	8% 16% 8% 18% 11% 8% 6% 3 3 3 16%	2458
	21st to end	Night	11% 16% 6% 13% 8% 7% 5% 3 4 5% 23%	2076
March	1st to 10th	Night	15% 17% 6% 15% 6% 7% 6% 2 4 4 18%	5484
	11th to 20th	Night	13% 16% 7% 12% 6% 5% 5% 3 4 6% 23%	5334
	21st to end	Night	15% 17% 5% 13% 7% 5% 4 2 3 4 23%	5213
April	1st to 10th	Night	19% 15% 6% 10% 6% 4 3 3 5% 4 25%	2100
	11th to 20th	Night	18% 17% 3 9% 5% 4 4 3 5% 5% 29%	2019
	21st to end	Night	20% 14% 3 7% 6% 4 4 3 5% 4 29%	1890
May	1st to 10th	Night	27% 15% 4 9% 5% 4 4 3 4 5% 22%	4144
	11th to 20th	Night	20% 12% 3 8% 5% 5% 4 3 5% 8% 28%	3707
	21st to end	Night	19% 10% 3 7% 4 4 4 3 5% 7% 32%	4014
June	1st to 10th	Night	26% 9% 3 8% 4 4 4 3 5% 6% 29%	1600
	11th to 20th	Night	18% 8% 2 6% 5% 5% 5% 4 6% 7% 35%	1600
	21st to end	Night	20% 8% 3 7% 6% 5% 5% 5% 6% 6% 29%	1600
July	1st to 10th	Night	14% 7% 3 8% 6% 6% 7% 5% 8% 8% 29%	3600
	11th to 20th	Night	18% 7% 3 8% 4 5% 5% 4 5% 7% 35%	3600
	21st to end	Night	12% 8% 3 7% 5% 5% 5% 4 7% 8% 38%	3926
August	1st to 10th	Night	22% 8% 3 7% 5% 5% 5% 3 6% 6% 30%	2649
	11th to 20th	Night	15% 8% 4 9% 5% 5% 7% 4 6% 7% 28%	2872
	21st to end	Night	17% 9% 2 7% 4 4 4 3 5% 6% 38%	3536
September	1st to 10th	Night	15% 8% 3 6% 3 5% 4 3 5% 6% 42%	2000
	11th to 20th	Night	15% 7% 2 6% 4 3 4 4 4 6% 45%	2178
	21st to end	Night	19% 9% 2 5% 3 4 4 3 5% 7% 39%	2200
October	1st to 10th	Night	19% 11% 3 7% 4 4 5% 4 4 6% 34%	2200
	11th to 20th	Night	18% 15% 3 8% 5% 5% 4 3 5% 6% 28%	2525
	21st to end	Night	22% 18% 4 8% 4 4 4 4 5% 5% 22%	2860
November	1st to 10th	Night	17% 19% 6% 9% 5% 4 4 3 5% 5% 24%	2667
	11th to 20th	Night	14% 17% 7% 15% 5% 3 4 2 4 4 24%	2730
	21st to end	Night	15% 19% 7% 15% 8% 5% 4 2 3 4 18%	2856
December	1st to 10th	Night	12% 17% 9% 26% 11% 5% 4 3 3 2 8%	4720
	11th to 20th	Night	16% 20% 7% 18% 8% 5% 3 2 3 3 14%	5348
	21st to end	Night	16% 18% 7% 16% 7% 6% 5% 2 4 5% 16%	7150

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	80% 3 7% 8% 2	4662
	11th to 20th	Day	79% 3 6% 8% 4 1	4680
	21st to end	Day	72% 2 8% 9% 9% 1	5124
February	1st to 10th	Day	72% 4 5% 12% 6% 1	1778
	11th to 20th	Day	73% 4 8% 9% 5% 1	2057
	21st to end	Day	67% 6% 7% 12% 7% 2	1730
March	1st to 10th	Day	71% 5% 6% 7% 8% 4	4579
	11th to 20th	Day	60% 4 13% 13% 9% 2	4844
	21st to end	Day	64% 4 5% 14% 13% 1	5956
April	1st to 10th	Day	63% 4 8% 14% 9% 2	2520
	11th to 20th	Day	57% 5% 9% 18% 11% 1	2550
	21st to end	Day	60% 4 8% 16% 8% 3	2730
May	1st to 10th	Day	67% 6% 7% 15% 5%	6027
	11th to 20th	Day	55% 9% 13% 15% 6% 1	6454
	21st to end	Day	51% 9% 12% 20% 8%	7103
June	1st to 10th	Day	59% 7% 11% 17% 5% 1	2800
	11th to 20th	Day	49% 8% 11% 22% 9% 1	2800
	21st to end	Day	56% 8% 10% 19% 6% 1	2800
July	1st to 10th	Day	53% 4 17% 19% 8%	6290
	11th to 20th	Day	46% 6% 15% 26% 7%	6285
	21st to end	Day	45% 5% 12% 30% 8%	6728
August	1st to 10th	Day	55% 6% 15% 19% 5%	4453
	11th to 20th	Day	56% 7% 15% 18% 4	4214
	21st to end	Day	47% 5% 15% 19% 12% 2	4359
September	1st to 10th	Day	43% 8% 12% 26% 11%	2400
	11th to 20th	Day	42% 5% 11% 26% 14% 1	2221
	21st to end	Day	47% 7% 13% 20% 12% 1	2200
October	1st to 10th	Day	51% 4 11% 22% 11%	3590
	11th to 20th	Day	53% 4 12% 22% 8%	3024
	21st to end	Day	55% 4 13% 19% 9% 1	3180
November	1st to 10th	Day	62% 5% 9% 16% 8% 1	1851
	11th to 20th	Day	67% 6% 8% 9% 8% 2	1890
	21st to end	Day	69% 6% 12% 11% 3	1759
December	1st to 10th	Day	80% 3 8% 6% 3	2680
	11th to 20th	Day	67% 3 8% 12% 9% 1	3066
	21st to end	Day	71% 5% 4 9% 9% 2	4048
January	1st to 10th	Night	81% 3 8% 7% 2	8234
	11th to 20th	Night	82% 3 5% 6% 3 1	8280
	21st to end	Night	71% 3 7% 9% 9% 1	9057
February	1st to 10th	Night	71% 5% 7% 11% 6%	2840
	11th to 20th	Night	73% 5% 6% 11% 5% 1	2460
	21st to end	Night	65% 5% 7% 13% 9% 1	2076
March	1st to 10th	Night	71% 3 7% 10% 7% 1	5494
	11th to 20th	Night	61% 6% 13% 12% 7% 1	5335
	21st to end	Night	66% 3 5% 13% 13% 1	5213
April	1st to 10th	Night	62% 4 8% 15% 9% 1	2100
	11th to 20th	Night	57% 6% 8% 18% 11%	2019
	21st to end	Night	57% 6% 9% 15% 11% 2	1890
May	1st to 10th	Night	64% 6% 12% 12% 5%	4150
	11th to 20th	Night	53% 10% 13% 18% 6% 1	3708
	21st to end	Night	50% 8% 13% 19% 10%	4015
June	1st to 10th	Night	56% 7% 10% 19% 8% 1	1600
	11th to 20th	Night	47% 8% 13% 21% 9% 2	1600
	21st to end	Night	52% 10% 12% 19% 7% 1	1600
July	1st to 10th	Night	50% 5% 18% 20% 6%	3560
	11th to 20th	Night	48% 5% 13% 27% 7%	3552
	21st to end	Night	44% 6% 16% 27% 8%	3809
August	1st to 10th	Night	54% 6% 13% 22% 4	2639
	11th to 20th	Night	52% 7% 17% 16% 7%	2899
	21st to end	Night	47% 4 14% 22% 13% 1	3536
September	1st to 10th	Night	42% 8% 15% 26% 9%	2000
	11th to 20th	Night	40% 6% 14% 27% 12% 1	2178
	21st to end	Night	44% 7% 12% 25% 11% 2	2200
October	1st to 10th	Night	51% 4 13% 22% 10%	3590
	11th to 20th	Night	55% 4 10% 20% 10%	4113
	21st to end	Night	54% 4 15% 17% 9% 1	4610
November	1st to 10th	Night	63% 5% 11% 15% 6% 1	2667
	11th to 20th	Night	64% 4 9% 14% 8% 2	2730
	21st to end	Night	71% 5% 9% 11% 4	2856
December	1st to 10th	Night	82% 3 7% 6% 2	4720
	11th to 20th	Night	77% 3 4 8% 7%	5348
	21st to end	Night	71% 5% 6% 10% 7% 2	7150

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% 25% 35% 11% 2	220
	11th to 20th	Day	34% 27% 30% 6% 3	220
	21st to end	Day	26% 26% 31% 14% 3	242
February	1st to 10th	Day	35% 29% 25% 9% 1	291
	11th to 20th	Day	32% 27% 29% 10% 2	536
	21st to end	Day	31% 26% 28% 13% 1	446
March	1st to 10th	Day	31% 27% 28% 11% 3	540
	11th to 20th	Day	34% 27% 25% 11% 3	540
	21st to end	Day	37% 24% 21% 12% 5% 1	594
April	1st to 10th	Day	40% 20% 24% 11% 5%	540
	11th to 20th	Day	38% 23% 23% 10% 5% 1	532
	21st to end	Day	35% 22% 26% 11% 4 2	540
May	1st to 10th	Day	43% 18% 23% 11% 4 1	543
	11th to 20th	Day	28% 20% 31% 16% 4 1	567
	21st to end	Day	25% 24% 29% 17% 5% 1	617
June	1st to 10th	Day	32% 17% 32% 12% 7%	530
	11th to 20th	Day	23% 18% 31% 19% 7% 1	530
	21st to end	Day	26% 19% 32% 15% 6% 2	530
July	1st to 10th	Day	19% 16% 35% 22% 7% 2	525
	11th to 20th	Day	15% 16% 37% 22% 7% 2	524
	21st to end	Day	20% 14% 35% 23% 6% 2	576
August	1st to 10th	Day	18% 14% 28% 22% 14% 3	526
	11th to 20th	Day	17% 11% 31% 22% 14% 4	519
	21st to end	Day	22% 15% 27% 22% 11% 4	583
September	1st to 10th	Day	21% 15% 25% 21% 12% 5%	530
	11th to 20th	Day	21% 12% 22% 20% 17% 9%	530
	21st to end	Day	20% 17% 24% 23% 11% 5%	530
October	1st to 10th	Day	26% 18% 23% 18% 12% 3	530
	11th to 20th	Day	29% 19% 27% 15% 9% 1	455
	21st to end	Day	35% 22% 23% 16% 5%	462
November	1st to 10th	Day	35% 20% 26% 15% 4	425
	11th to 20th	Day	29% 25% 27% 12% 5% 1	430
	21st to end	Day	37% 20% 28% 12% 2 1	299
December	1st to 10th	Day	33% 22% 27% 15% 3	220
	11th to 20th	Day	35% 27% 29% 6% 2	220
	21st to end	Day	37% 20% 29% 11% 3	242
January	1st to 10th	Night	26% 27% 32% 13% 2	840
	11th to 20th	Night	27% 23% 30% 16% 4	840
	21st to end	Night	21% 24% 32% 19% 4	924
February	1st to 10th	Night	23% 27% 30% 17% 3	840
	11th to 20th	Night	23% 27% 31% 16% 2	823
	21st to end	Night	25% 22% 34% 19% 1	692
March	1st to 10th	Night	27% 22% 31% 17% 3	840
	11th to 20th	Night	32% 20% 27% 16% 6%	840
	21st to end	Night	31% 20% 25% 18% 6% 1	924
April	1st to 10th	Night	33% 21% 25% 16% 4	840
	11th to 20th	Night	32% 19% 25% 19% 5%	775
	21st to end	Night	31% 18% 27% 18% 6%	630
May	1st to 10th	Night	29% 14% 31% 19% 6% 1	630
	11th to 20th	Night	22% 15% 32% 24% 7% 1	440
	21st to end	Night	23% 10% 27% 31% 9%	455
June	1st to 10th	Night	30% 10% 24% 28% 9%	400
	11th to 20th	Night	21% 10% 22% 33% 15%	400
	21st to end	Night	22% 10% 24% 35% 10% 1	400
July	1st to 10th	Night	18% 6% 26% 38% 12% 1	390
	11th to 20th	Night	17% 6% 23% 37% 16% 1	388
	21st to end	Night	15% 5% 24% 40% 16% 1	438
August	1st to 10th	Night	18% 4 18% 40% 20%	435
	11th to 20th	Night	17% 9% 22% 31% 20% 1	592
	21st to end	Night	20% 7% 20% 33% 17% 2	843
September	1st to 10th	Night	19% 10% 22% 33% 15% 1	800
	11th to 20th	Night	20% 9% 18% 27% 25% 2	800
	21st to end	Night	24% 11% 23% 24% 16% 2	800
October	1st to 10th	Night	26% 12% 20% 26% 14% 1	800
	11th to 20th	Night	28% 18% 22% 22% 9% 2	800
	21st to end	Night	33% 19% 25% 19% 4	880
November	1st to 10th	Night	31% 19% 24% 19% 6%	820
	11th to 20th	Night	26% 23% 26% 16% 8% 1	840
	21st to end	Night	30% 23% 26% 16% 5% 1	840
December	1st to 10th	Night	31% 24% 27% 15% 4	840
	11th to 20th	Night	31% 24% 27% 14% 4	840
	21st to end	Night	34% 20% 27% 15% 3	924

Page generated at 2026-05-29 01:53:27. Version ac07

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