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 2024-01-27.

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	18% 13% 5% 9% 7% 4 5% 5% 5% 6% 26%	74900
	Night	17% 13% 6% 10% 7% 4 5% 4 4 5% 25%	75143
Transparency	Day	59% 7% 10% 16% 7% 1	74605
	Night	61% 7% 10% 15% 7% 1	74972
Seeing	Day	28% 20% 27% 16% 7% 2	13673
	Night	26% 18% 26% 22% 8% 1	22678

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	13% 15% 10% 18% 11% 5% 4 5% 4 3 11%	1517
	11th to 20th	Day	13% 19% 7% 13% 13% 4 3 4 5% 3 16%	1520
	21st to end	Day	9% 14% 9% 13% 10% 4 7% 5% 4 4 20%	1632
February	1st to 10th	Day	14% 16% 8% 14% 11% 6% 7% 3 3 3 15%	1524
	11th to 20th	Day	10% 15% 11% 15% 11% 5% 6% 4 3 4 16%	1748
	21st to end	Day	11% 17% 7% 15% 9% 4 6% 4 3 4 19%	1480
March	1st to 10th	Day	12% 16% 9% 11% 9% 4 5% 4 4 4 22%	1797
	11th to 20th	Day	14% 14% 7% 10% 8% 3 4 4 3 4 29%	1880
	21st to end	Day	16% 17% 7% 11% 8% 3 3 2 3 4 26%	2317
April	1st to 10th	Day	19% 17% 6% 10% 6% 2 3 3 3 5% 25%	2160
	11th to 20th	Day	17% 15% 4 8% 6% 3 3 4 4 5% 32%	2181
	21st to end	Day	22% 16% 4 8% 5% 3 5% 4 4 5% 25%	2340
May	1st to 10th	Day	24% 14% 4 5% 5% 3 3 4 4 6% 29%	2340
	11th to 20th	Day	21% 10% 4 7% 5% 3 4 4 4 5% 32%	2470
	21st to end	Day	18% 7% 4 7% 6% 3 6% 6% 7% 9% 27%	2725
June	1st to 10th	Day	27% 10% 3 6% 6% 3 5% 5% 5% 7% 23%	2520
	11th to 20th	Day	19% 7% 3 6% 6% 3 5% 5% 6% 8% 32%	2520
	21st to end	Day	22% 9% 3 8% 6% 4 5% 6% 6% 7% 25%	2520
July	1st to 10th	Day	18% 7% 3 7% 5% 4 5% 5% 7% 8% 31%	2520
	11th to 20th	Day	15% 7% 3 8% 7% 4 6% 7% 8% 8% 27%	2520
	21st to end	Day	19% 6% 3 7% 6% 4 6% 5% 6% 9% 28%	2744
August	1st to 10th	Day	17% 7% 3 8% 6% 4 6% 6% 6% 9% 29%	2454
	11th to 20th	Day	15% 8% 4 7% 6% 4 6% 6% 7% 9% 28%	2304
	21st to end	Day	18% 9% 2 5% 6% 3 5% 5% 5% 8% 34%	2408
September	1st to 10th	Day	18% 7% 3 5% 6% 3 5% 5% 5% 7% 37%	2160
	11th to 20th	Day	19% 8% 3 4 5% 2 5% 4 4 7% 40%	1999
	21st to end	Day	17% 9% 3 6% 5% 3 4 6% 5% 8% 33%	1980
October	1st to 10th	Day	23% 13% 4 6% 5% 4 4 5% 5% 6% 27%	1980
	11th to 20th	Day	16% 15% 5% 8% 7% 3 4 5% 6% 6% 26%	1687
	21st to end	Day	23% 22% 5% 6% 5% 3 3 3 3 4 21%	1782
November	1st to 10th	Day	16% 17% 6% 8% 6% 4 4 4 3 5% 26%	1671
	11th to 20th	Day	16% 17% 8% 12% 7% 3 4 5% 4 4 21%	1710
	21st to end	Day	17% 14% 8% 13% 7% 3 6% 4 4 5% 19%	1592
December	1st to 10th	Day	16% 22% 10% 14% 8% 3 3 3 3 4 14%	1520
	11th to 20th	Day	16% 18% 8% 12% 7% 3 4 3 4 4 20%	1906
	21st to end	Day	21% 17% 8% 14% 9% 4 4 4 3 3 14%	2772
January	1st to 10th	Night	12% 18% 9% 17% 11% 4 6% 5% 3 3 11%	2649
	11th to 20th	Night	13% 16% 8% 14% 11% 5% 7% 5% 4 4 13%	2660
	21st to end	Night	9% 15% 8% 14% 11% 5% 8% 5% 4 4 16%	2868
February	1st to 10th	Night	12% 15% 7% 15% 13% 7% 7% 4 3 4 15%	2434
	11th to 20th	Night	9% 15% 9% 15% 12% 5% 8% 4 3 4 17%	2098
	21st to end	Night	12% 15% 7% 11% 10% 5% 7% 3 3 5% 22%	1776
March	1st to 10th	Night	12% 16% 8% 11% 8% 4 6% 4 4 5% 22%	2150
	11th to 20th	Night	14% 15% 7% 10% 6% 3 5% 4 3 5% 26%	2079
	21st to end	Night	17% 15% 5% 11% 6% 3 4 3 3 4 28%	2034
April	1st to 10th	Night	19% 14% 6% 9% 8% 3 3 4 5% 4 25%	1800
	11th to 20th	Night	18% 13% 4 7% 6% 3 4 4 5% 5% 31%	1728
	21st to end	Night	21% 14% 4 6% 7% 3 4 4 4 4 28%	1620
May	1st to 10th	Night	21% 13% 4 7% 6% 2 4 4 5% 6% 29%	1620
	11th to 20th	Night	19% 8% 3 6% 6% 3 5% 4 4 9% 33%	1438
	21st to end	Night	20% 7% 3 6% 5% 3 5% 4 5% 8% 34%	1550
June	1st to 10th	Night	27% 8% 3 6% 5% 3 5% 4 5% 6% 29%	1440
	11th to 20th	Night	18% 8% 2 5% 5% 3 6% 4 6% 7% 35%	1440
	21st to end	Night	20% 7% 4 6% 6% 3 6% 6% 6% 7% 30%	1440
July	1st to 10th	Night	15% 6% 2 6% 5% 4 7% 5% 6% 8% 35%	1440
	11th to 20th	Night	15% 6% 3 5% 5% 3 5% 5% 7% 10% 36%	1440
	21st to end	Night	15% 7% 3 5% 7% 4 6% 5% 7% 7% 35%	1574
August	1st to 10th	Night	15% 6% 2 4 5% 4 5% 5% 7% 8% 38%	1465
	11th to 20th	Night	15% 7% 4 8% 4 3 5% 5% 7% 7% 35%	1596
	21st to end	Night	17% 7% 2 6% 4 3 4 4 4 8% 41%	1946
September	1st to 10th	Night	16% 7% 3 5% 4 4 5% 4 5% 7% 40%	1800
	11th to 20th	Night	17% 7% 3 5% 4 3 3 5% 4 6% 43%	1960
	21st to end	Night	19% 8% 2 5% 4 2 4 4 5% 7% 39%	1980
October	1st to 10th	Night	20% 11% 3 6% 5% 3 4 5% 4 6% 32%	1980
	11th to 20th	Night	19% 15% 3 8% 6% 4 5% 4 5% 6% 26%	2271
	21st to end	Night	24% 17% 4 7% 5% 3 4 5% 4 5% 21%	2574
November	1st to 10th	Night	17% 17% 5% 9% 5% 3 4 4 5% 5% 24%	2407
	11th to 20th	Night	15% 14% 8% 12% 7% 3 4 3 4 5% 25%	2470
	21st to end	Night	16% 16% 9% 12% 10% 4 4 3 3 4 19%	2584
December	1st to 10th	Night	18% 20% 10% 14% 7% 4 4 4 3 3 12%	2660
	11th to 20th	Night	17% 19% 8% 15% 10% 4 5% 3 3 4 13%	3288
	21st to end	Night	21% 17% 7% 16% 8% 3 4 4 3 3 14%	4884

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% 5% 8% 9% 2	1518
	11th to 20th	Day	72% 5% 7% 10% 5% 1	1520
	21st to end	Day	68% 4 9% 11% 7% 1	1632
February	1st to 10th	Day	75% 4 5% 10% 5% 1	1524
	11th to 20th	Day	73% 4 8% 9% 5% 1	1757
	21st to end	Day	68% 6% 7% 10% 7% 2	1480
March	1st to 10th	Day	67% 5% 8% 12% 6% 3	1800
	11th to 20th	Day	60% 5% 11% 12% 10% 2	1880
	21st to end	Day	64% 3 7% 15% 9% 2	2317
April	1st to 10th	Day	63% 5% 8% 13% 9% 2	2160
	11th to 20th	Day	56% 5% 9% 19% 11% 1	2181
	21st to end	Day	62% 5% 9% 14% 7% 3	2340
May	1st to 10th	Day	57% 5% 7% 19% 10% 1	2340
	11th to 20th	Day	54% 7% 9% 18% 11% 1	2474
	21st to end	Day	51% 11% 13% 17% 8% 1	2725
June	1st to 10th	Day	60% 8% 11% 16% 5% 1	2520
	11th to 20th	Day	49% 8% 11% 21% 9% 1	2520
	21st to end	Day	57% 9% 11% 17% 6%	2520
July	1st to 10th	Day	48% 8% 14% 20% 9%	2450
	11th to 20th	Day	49% 10% 14% 21% 6%	2445
	21st to end	Day	53% 9% 13% 19% 6%	2591
August	1st to 10th	Day	50% 10% 16% 19% 5%	2440
	11th to 20th	Day	49% 10% 17% 17% 7%	2304
	21st to end	Day	47% 8% 13% 20% 11%	2408
September	1st to 10th	Day	45% 8% 13% 22% 10%	2160
	11th to 20th	Day	44% 6% 11% 26% 13% 1	1999
	21st to end	Day	47% 8% 13% 20% 10% 1	1980
October	1st to 10th	Day	57% 7% 11% 17% 8%	1980
	11th to 20th	Day	56% 7% 15% 16% 5%	1687
	21st to end	Day	68% 6% 8% 11% 6% 2	1782
November	1st to 10th	Day	60% 5% 10% 16% 8% 1	1671
	11th to 20th	Day	66% 6% 8% 9% 8% 2	1710
	21st to end	Day	67% 6% 13% 11% 3	1592
December	1st to 10th	Day	76% 4 7% 8% 4	1520
	11th to 20th	Day	69% 4 7% 12% 7% 1	1906
	21st to end	Day	76% 7% 4 9% 5%	2772
January	1st to 10th	Night	78% 5% 6% 7% 3	2649
	11th to 20th	Night	76% 5% 7% 8% 3 1	2660
	21st to end	Night	71% 5% 8% 10% 5% 1	2868
February	1st to 10th	Night	73% 6% 7% 9% 5%	2434
	11th to 20th	Night	73% 5% 6% 11% 5% 1	2100
	21st to end	Night	66% 6% 7% 12% 8% 1	1776
March	1st to 10th	Night	66% 5% 7% 14% 7% 2	2160
	11th to 20th	Night	61% 6% 8% 13% 10% 1	2080
	21st to end	Night	61% 4 7% 16% 9% 2	2034
April	1st to 10th	Night	63% 5% 9% 14% 10% 1	1800
	11th to 20th	Night	53% 7% 9% 20% 11%	1728
	21st to end	Night	58% 7% 9% 14% 10% 2	1620
May	1st to 10th	Night	56% 5% 9% 17% 11% 1	1620
	11th to 20th	Night	50% 8% 12% 18% 11% 2	1439
	21st to end	Night	50% 7% 14% 19% 9% 1	1551
June	1st to 10th	Night	56% 7% 10% 19% 7%	1440
	11th to 20th	Night	47% 8% 12% 21% 9% 2	1440
	21st to end	Night	52% 11% 12% 18% 6%	1440
July	1st to 10th	Night	44% 12% 13% 20% 10%	1400
	11th to 20th	Night	41% 11% 15% 26% 7%	1392
	21st to end	Night	45% 11% 15% 20% 9%	1486
August	1st to 10th	Night	41% 10% 18% 26% 5%	1455
	11th to 20th	Night	45% 10% 18% 19% 8%	1596
	21st to end	Night	42% 7% 15% 24% 11%	1946
September	1st to 10th	Night	43% 8% 15% 24% 9%	1800
	11th to 20th	Night	42% 6% 14% 26% 11% 1	1960
	21st to end	Night	43% 8% 13% 25% 10% 2	1980
October	1st to 10th	Night	52% 7% 11% 18% 11% 1	1980
	11th to 20th	Night	58% 7% 12% 17% 5%	2271
	21st to end	Night	64% 8% 10% 11% 7% 1	2574
November	1st to 10th	Night	62% 5% 11% 14% 7% 1	2407
	11th to 20th	Night	63% 4 9% 14% 7% 2	2470
	21st to end	Night	70% 6% 10% 11% 4	2584
December	1st to 10th	Night	77% 5% 8% 7% 3	2660
	11th to 20th	Night	77% 5% 5% 8% 6%	3288
	21st to end	Night	75% 6% 6% 9% 4	4884

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% 24% 35% 12% 2	180
	11th to 20th	Day	34% 26% 29% 7% 3 1	180
	21st to end	Day	24% 29% 31% 13% 4	188
February	1st to 10th	Day	41% 28% 24% 6% 1	217
	11th to 20th	Day	33% 28% 28% 8% 2	416
	21st to end	Day	33% 26% 25% 14% 2	346
March	1st to 10th	Day	30% 27% 28% 12% 3	420
	11th to 20th	Day	31% 26% 25% 13% 4	420
	21st to end	Day	34% 23% 22% 14% 6% 1	462
April	1st to 10th	Day	40% 19% 23% 11% 6%	420
	11th to 20th	Day	35% 22% 24% 11% 6% 2	412
	21st to end	Day	35% 22% 26% 12% 4 1	420
May	1st to 10th	Day	41% 18% 23% 11% 5% 1	423
	11th to 20th	Day	28% 20% 31% 14% 4 2	447
	21st to end	Day	23% 23% 29% 18% 6% 1	485
June	1st to 10th	Day	34% 18% 30% 12% 6%	450
	11th to 20th	Day	24% 19% 29% 20% 8% 2	450
	21st to end	Day	24% 19% 33% 15% 7% 2	450
July	1st to 10th	Day	20% 16% 32% 23% 7% 2	445
	11th to 20th	Day	16% 16% 36% 22% 8% 2	444
	21st to end	Day	20% 14% 34% 24% 6% 2	488
August	1st to 10th	Day	19% 15% 29% 21% 14% 2	446
	11th to 20th	Day	17% 12% 31% 22% 14% 3	439
	21st to end	Day	23% 16% 25% 20% 11% 4	495
September	1st to 10th	Day	23% 15% 24% 21% 12% 5%	450
	11th to 20th	Day	24% 13% 22% 19% 15% 7%	450
	21st to end	Day	20% 18% 24% 23% 11% 5%	450
October	1st to 10th	Day	28% 18% 22% 17% 12% 2	450
	11th to 20th	Day	29% 20% 28% 14% 8% 1	389
	21st to end	Day	37% 22% 22% 15% 5%	396
November	1st to 10th	Day	33% 20% 25% 17% 4	365
	11th to 20th	Day	30% 26% 27% 11% 5% 1	370
	21st to end	Day	35% 19% 29% 13% 3 1	252
December	1st to 10th	Day	36% 23% 24% 13% 3	180
	11th to 20th	Day	35% 27% 28% 7% 3	180
	21st to end	Day	39% 21% 30% 9% 1	198
January	1st to 10th	Night	26% 26% 32% 13% 2	760
	11th to 20th	Night	27% 24% 29% 16% 4	760
	21st to end	Night	21% 25% 31% 19% 3	820
February	1st to 10th	Night	24% 28% 31% 15% 2	720
	11th to 20th	Night	24% 27% 31% 16% 3	703
	21st to end	Night	26% 22% 32% 19% 1	592
March	1st to 10th	Night	26% 21% 31% 19% 3	720
	11th to 20th	Night	32% 19% 27% 17% 6%	720
	21st to end	Night	31% 20% 23% 18% 7% 1	792
April	1st to 10th	Night	33% 21% 24% 17% 4	720
	11th to 20th	Night	30% 17% 26% 20% 6%	664
	21st to end	Night	31% 18% 27% 18% 6%	540
May	1st to 10th	Night	28% 15% 30% 19% 7% 1	540
	11th to 20th	Night	22% 15% 30% 25% 7% 1	377
	21st to end	Night	22% 10% 27% 31% 10% 1	389
June	1st to 10th	Night	30% 10% 23% 28% 9%	360
	11th to 20th	Night	21% 9% 21% 33% 15%	360
	21st to end	Night	20% 10% 22% 36% 11% 1	360
July	1st to 10th	Night	18% 6% 27% 36% 13% 1	350
	11th to 20th	Night	16% 6% 24% 37% 16% 1	348
	21st to end	Night	15% 6% 23% 39% 16% 1	394
August	1st to 10th	Night	18% 3 19% 40% 20%	391
	11th to 20th	Night	17% 9% 22% 31% 19% 1	532
	21st to end	Night	20% 8% 20% 33% 18% 2	758
September	1st to 10th	Night	20% 10% 22% 33% 15% 1	720
	11th to 20th	Night	22% 10% 19% 27% 21% 2	720
	21st to end	Night	24% 12% 23% 24% 15% 2	720
October	1st to 10th	Night	28% 12% 21% 24% 14% 1	720
	11th to 20th	Night	28% 18% 22% 21% 9% 2	720
	21st to end	Night	34% 20% 24% 18% 4	792
November	1st to 10th	Night	31% 18% 24% 20% 7% 1	740
	11th to 20th	Night	27% 23% 26% 16% 8% 1	760
	21st to end	Night	31% 23% 25% 16% 5% 1	760
December	1st to 10th	Night	32% 25% 25% 14% 4	760
	11th to 20th	Night	31% 24% 26% 15% 4	760
	21st to end	Night	35% 20% 28% 15% 2	836

Page generated at 2024-01-24 09:37:25. Version ac07

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