Conway
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Conway 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	16% 7% 3 5% 5% 3 5% 5% 5% 7% 38%	78277
	Night	16% 7% 3 5% 5% 3 5% 5% 5% 7% 39%	81013
Transparency	Day	45% 7% 12% 21% 13% 2	77982
	Night	44% 7% 13% 21% 13% 2	80842
Seeing	Day	22% 15% 29% 22% 9% 3	13898
	Night	20% 10% 28% 31% 10% 1	22921

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	14% 8% 3 5% 7% 3 5% 5% 5% 6% 38%	2517
	11th to 20th	Day	14% 7% 3 6% 6% 4 6% 6% 5% 6% 35%	2520
	21st to end	Day	14% 11% 3 6% 6% 3 4 4 6% 7% 36%	2772
February	1st to 10th	Day	13% 9% 3 6% 5% 3 6% 5% 4 8% 37%	1670
	11th to 20th	Day	12% 7% 3 7% 6% 4 5% 5% 6% 7% 39%	1848
	21st to end	Day	14% 10% 4 5% 6% 4 6% 6% 5% 5% 35%	1520
March	1st to 10th	Day	13% 9% 4 5% 6% 4 5% 6% 5% 7% 37%	1797
	11th to 20th	Day	15% 8% 4 5% 5% 3 5% 5% 4 6% 41%	1898
	21st to end	Day	14% 8% 4 6% 6% 3 3 4 3 6% 42%	2290
April	1st to 10th	Day	18% 9% 3 5% 5% 3 4 4 4 7% 38%	2160
	11th to 20th	Day	16% 6% 2 5% 7% 3 5% 4 5% 8% 39%	2181
	21st to end	Day	22% 8% 3 7% 5% 4 4 4 5% 6% 33%	2340
May	1st to 10th	Day	23% 8% 3 5% 5% 3 5% 4 5% 6% 32%	2340
	11th to 20th	Day	18% 7% 2 6% 5% 4 4 4 5% 5% 39%	2397
	21st to end	Day	16% 6% 3 5% 5% 4 5% 5% 6% 7% 38%	2725
June	1st to 10th	Day	22% 7% 3 5% 6% 4 5% 5% 5% 8% 31%	2520
	11th to 20th	Day	17% 7% 2 6% 5% 3 4 5% 6% 8% 38%	2520
	21st to end	Day	20% 6% 3 5% 5% 4 6% 6% 6% 8% 31%	2520
July	1st to 10th	Day	16% 5% 3 5% 5% 3 5% 6% 6% 9% 38%	2520
	11th to 20th	Day	12% 6% 3 5% 6% 4 6% 6% 6% 10% 36%	2520
	21st to end	Day	14% 5% 2 5% 5% 3 5% 7% 7% 8% 37%	2744
August	1st to 10th	Day	13% 6% 2 5% 6% 4 6% 6% 7% 7% 38%	2399
	11th to 20th	Day	13% 6% 2 6% 5% 4 6% 5% 7% 8% 38%	2304
	21st to end	Day	11% 4 2 5% 5% 2 5% 5% 5% 9% 46%	2407
September	1st to 10th	Day	13% 4 2 3 4 3 5% 4 6% 9% 47%	2157
	11th to 20th	Day	14% 4 2 3 4 3 4 4 4 5% 54%	1980
	21st to end	Day	16% 4 2 4 4 3 5% 4 5% 6% 47%	1980
October	1st to 10th	Day	21% 6% 2 5% 4 2 4 4 4 6% 40%	1980
	11th to 20th	Day	16% 7% 2 4 4 3 5% 4 5% 7% 42%	1718
	21st to end	Day	24% 8% 2 5% 5% 3 4 5% 5% 5% 34%	1782
November	1st to 10th	Day	14% 6% 2 4 4 3 4 5% 5% 7% 45%	1671
	11th to 20th	Day	18% 4 2 3 5% 3 6% 4 6% 8% 40%	1710
	21st to end	Day	20% 6% 3 4 4 3 4 5% 5% 6% 40%	1672
December	1st to 10th	Day	19% 8% 4 7% 5% 4 5% 5% 5% 7% 32%	1520
	11th to 20th	Day	20% 8% 3 4 4 3 4 4 4 5% 40%	1906
	21st to end	Day	23% 10% 3 5% 5% 3 5% 5% 6% 5% 30%	2772
January	1st to 10th	Night	16% 7% 3 5% 4 3 4 5% 5% 7% 41%	4429
	11th to 20th	Night	11% 8% 3 8% 8% 5% 6% 7% 7% 7% 30%	4440
	21st to end	Night	17% 10% 4 9% 7% 3 5% 5% 5% 6% 29%	4884
February	1st to 10th	Night	12% 9% 3 6% 6% 4 5% 5% 6% 8% 36%	2504
	11th to 20th	Night	10% 8% 3 6% 5% 3 6% 6% 6% 6% 42%	2218
	21st to end	Night	12% 9% 3 4 5% 3 4 5% 6% 9% 39%	1831
March	1st to 10th	Night	11% 9% 4 5% 5% 3 5% 6% 4 6% 40%	2150
	11th to 20th	Night	15% 8% 4 5% 5% 3 6% 5% 6% 7% 37%	2059
	21st to end	Night	15% 9% 3 5% 5% 2 4 4 4 6% 42%	2064
April	1st to 10th	Night	18% 9% 3 6% 5% 3 5% 5% 4 6% 38%	1800
	11th to 20th	Night	17% 6% 3 5% 6% 3 5% 5% 6% 7% 39%	1728
	21st to end	Night	24% 6% 2 4 4 3 4 4 6% 6% 36%	1620
May	1st to 10th	Night	21% 9% 3 5% 5% 3 6% 4 5% 6% 34%	1620
	11th to 20th	Night	19% 6% 2 5% 5% 4 5% 5% 6% 7% 37%	1510
	21st to end	Night	16% 6% 3 6% 5% 3 5% 5% 6% 8% 37%	1550
June	1st to 10th	Night	21% 6% 3 4 5% 3 4 5% 6% 6% 36%	1440
	11th to 20th	Night	19% 5% 2 3 3 3 4 5% 6% 7% 41%	1440
	21st to end	Night	18% 5% 2 4 5% 3 5% 4 6% 8% 39%	1440
July	1st to 10th	Night	16% 5% 2 4 4 3 4 6% 6% 8% 43%	1440
	11th to 20th	Night	14% 4 2 4 5% 4 5% 5% 5% 9% 43%	1440
	21st to end	Night	13% 4 1 4 5% 3 5% 5% 7% 9% 44%	1574
August	1st to 10th	Night	15% 4 2 4 4 3 4 5% 6% 7% 46%	1520
	11th to 20th	Night	14% 7% 2 5% 5% 4 4 4 6% 8% 41%	1596
	21st to end	Night	14% 6% 2 3 4 2 4 3 6% 8% 48%	1947
September	1st to 10th	Night	12% 4 2 4 3 2 3 5% 5% 7% 52%	1802
	11th to 20th	Night	15% 5% 1 3 3 2 3 4 4 6% 52%	1980
	21st to end	Night	15% 5% 2 4 4 2 4 4 5% 7% 48%	1980
October	1st to 10th	Night	20% 6% 2 5% 5% 3 5% 4 5% 6% 40%	1980
	11th to 20th	Night	16% 6% 2 5% 5% 3 4 5% 6% 8% 40%	2236
	21st to end	Night	24% 6% 3 5% 5% 3 5% 3 5% 5% 36%	2574
November	1st to 10th	Night	15% 5% 3 5% 4 3 5% 4 6% 6% 44%	2407
	11th to 20th	Night	16% 6% 2 5% 6% 3 5% 4 5% 7% 42%	2470
	21st to end	Night	15% 7% 3 5% 5% 3 5% 5% 4 7% 43%	2508
December	1st to 10th	Night	18% 9% 3 5% 6% 4 5% 5% 4 5% 36%	2660
	11th to 20th	Night	20% 9% 3 4 5% 3 4 5% 5% 6% 38%	3288
	21st to end	Night	20% 10% 3 6% 5% 3 5% 4 5% 6% 34%	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	42% 6% 13% 27% 11% 1	2518
	11th to 20th	Day	46% 8% 13% 22% 9% 2	2520
	21st to end	Day	47% 7% 13% 21% 11% 1	2772
February	1st to 10th	Day	47% 6% 15% 19% 11% 2	1670
	11th to 20th	Day	45% 7% 11% 19% 14% 4	1857
	21st to end	Day	50% 5% 12% 16% 14% 3	1520
March	1st to 10th	Day	46% 7% 12% 17% 13% 4	1800
	11th to 20th	Day	45% 5% 11% 17% 17% 5%	1898
	21st to end	Day	46% 5% 9% 17% 17% 5%	2290
April	1st to 10th	Day	47% 6% 10% 20% 14% 4	2160
	11th to 20th	Day	44% 7% 12% 20% 15% 2	2181
	21st to end	Day	52% 6% 10% 16% 13% 3	2340
May	1st to 10th	Day	52% 5% 8% 20% 12% 2	2340
	11th to 20th	Day	47% 6% 10% 18% 16% 3	2401
	21st to end	Day	45% 7% 14% 21% 12% 2	2725
June	1st to 10th	Day	52% 6% 13% 19% 9% 1	2520
	11th to 20th	Day	43% 6% 13% 20% 15% 2	2520
	21st to end	Day	50% 10% 12% 18% 9% 1	2520
July	1st to 10th	Day	41% 8% 13% 23% 13% 1	2450
	11th to 20th	Day	42% 9% 15% 24% 9% 1	2445
	21st to end	Day	39% 10% 15% 23% 12% 1	2591
August	1st to 10th	Day	42% 9% 15% 24% 11%	2385
	11th to 20th	Day	42% 8% 16% 23% 11% 1	2304
	21st to end	Day	34% 7% 15% 25% 17% 2	2407
September	1st to 10th	Day	33% 8% 15% 28% 15% 1	2157
	11th to 20th	Day	33% 5% 9% 31% 20% 3	1980
	21st to end	Day	37% 6% 13% 24% 19% 2	1980
October	1st to 10th	Day	47% 6% 11% 20% 14% 2	1980
	11th to 20th	Day	41% 6% 14% 29% 10% 1	1718
	21st to end	Day	51% 6% 11% 18% 12% 2	1782
November	1st to 10th	Day	37% 7% 15% 25% 14% 2	1671
	11th to 20th	Day	41% 6% 14% 19% 17% 3	1710
	21st to end	Day	44% 6% 17% 20% 12% 1	1672
December	1st to 10th	Day	52% 6% 13% 20% 9% 1	1520
	11th to 20th	Day	47% 5% 10% 18% 17% 2	1906
	21st to end	Day	54% 7% 10% 18% 9% 2	2772
January	1st to 10th	Night	41% 7% 14% 25% 10% 3	4429
	11th to 20th	Night	46% 9% 15% 17% 10% 2	4440
	21st to end	Night	53% 8% 11% 17% 10% 2	4884
February	1st to 10th	Night	47% 6% 13% 18% 14% 3	2504
	11th to 20th	Night	41% 7% 12% 22% 15% 3	2220
	21st to end	Night	43% 7% 12% 21% 13% 4	1831
March	1st to 10th	Night	45% 5% 10% 22% 14% 3	2160
	11th to 20th	Night	46% 8% 11% 18% 13% 4	2060
	21st to end	Night	44% 5% 9% 17% 20% 5%	2064
April	1st to 10th	Night	49% 5% 10% 19% 15% 3	1800
	11th to 20th	Night	44% 6% 11% 23% 15% 1	1728
	21st to end	Night	48% 5% 12% 18% 13% 3	1620
May	1st to 10th	Night	52% 6% 8% 20% 12% 2	1620
	11th to 20th	Night	46% 8% 11% 18% 14% 4	1511
	21st to end	Night	45% 8% 15% 21% 10% 2	1551
June	1st to 10th	Night	48% 8% 12% 20% 12%	1440
	11th to 20th	Night	43% 9% 15% 19% 13% 2	1440
	21st to end	Night	43% 9% 15% 22% 10% 1	1440
July	1st to 10th	Night	37% 9% 17% 22% 15% 1	1400
	11th to 20th	Night	38% 7% 17% 26% 12%	1392
	21st to end	Night	35% 8% 17% 27% 12% 1	1486
August	1st to 10th	Night	37% 9% 16% 26% 12%	1510
	11th to 20th	Night	40% 8% 16% 22% 14%	1596
	21st to end	Night	35% 7% 14% 27% 16% 1	1947
September	1st to 10th	Night	31% 8% 15% 31% 16%	1802
	11th to 20th	Night	34% 6% 11% 29% 18% 2	1980
	21st to end	Night	36% 7% 13% 28% 14% 2	1980
October	1st to 10th	Night	45% 7% 13% 20% 13% 2	1980
	11th to 20th	Night	42% 7% 14% 26% 10% 1	2236
	21st to end	Night	51% 6% 11% 19% 12% 2	2574
November	1st to 10th	Night	40% 6% 12% 24% 15% 2	2407
	11th to 20th	Night	42% 6% 11% 23% 15% 2	2470
	21st to end	Night	42% 6% 16% 23% 12% 1	2508
December	1st to 10th	Night	50% 7% 12% 21% 9% 1	2660
	11th to 20th	Night	46% 7% 12% 17% 17% 1	3288
	21st to end	Night	53% 7% 10% 20% 10% 1	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	26% 18% 27% 22% 7% 1	180
	11th to 20th	Day	26% 22% 23% 23% 5% 1	180
	21st to end	Day	17% 19% 34% 22% 8%	198
February	1st to 10th	Day	23% 23% 32% 18% 4	300
	11th to 20th	Day	23% 22% 35% 17% 3	456
	21st to end	Day	23% 20% 30% 22% 4	362
March	1st to 10th	Day	25% 17% 31% 23% 4	420
	11th to 20th	Day	25% 21% 31% 15% 6% 1	420
	21st to end	Day	24% 18% 31% 17% 8% 3	462
April	1st to 10th	Day	30% 18% 27% 16% 7% 2	420
	11th to 20th	Day	25% 21% 28% 16% 8% 2	412
	21st to end	Day	30% 20% 30% 13% 6% 2	420
May	1st to 10th	Day	33% 17% 29% 15% 4 2	423
	11th to 20th	Day	23% 17% 33% 19% 6% 2	447
	21st to end	Day	21% 16% 31% 21% 9% 2	485
June	1st to 10th	Day	22% 14% 35% 18% 8% 2	450
	11th to 20th	Day	18% 17% 32% 23% 7% 3	450
	21st to end	Day	21% 12% 36% 16% 12% 2	450
July	1st to 10th	Day	19% 9% 29% 24% 15% 3	445
	11th to 20th	Day	14% 7% 34% 30% 13% 3	444
	21st to end	Day	14% 8% 33% 29% 13% 3	488
August	1st to 10th	Day	11% 12% 28% 27% 17% 5%	446
	11th to 20th	Day	14% 9% 29% 26% 14% 7%	439
	21st to end	Day	13% 10% 26% 31% 14% 6%	495
September	1st to 10th	Day	16% 9% 24% 27% 17% 6%	450
	11th to 20th	Day	19% 11% 26% 20% 14% 10%	450
	21st to end	Day	16% 12% 28% 25% 14% 6%	450
October	1st to 10th	Day	26% 14% 20% 21% 15% 5%	450
	11th to 20th	Day	21% 13% 25% 25% 14% 2	385
	21st to end	Day	34% 10% 26% 24% 6% 1	396
November	1st to 10th	Day	20% 16% 26% 28% 8% 2	365
	11th to 20th	Day	28% 16% 26% 22% 8% 1	370
	21st to end	Day	27% 16% 30% 20% 7%	332
December	1st to 10th	Day	23% 27% 21% 21% 7% 1	180
	11th to 20th	Day	27% 21% 32% 15% 4	180
	21st to end	Day	31% 17% 29% 19% 4 1	198
January	1st to 10th	Night	18% 12% 35% 31% 4	760
	11th to 20th	Night	23% 15% 29% 29% 4	760
	21st to end	Night	17% 14% 36% 27% 6% 1	836
February	1st to 10th	Night	19% 14% 34% 30% 3	760
	11th to 20th	Night	17% 14% 42% 23% 4	743
	21st to end	Night	18% 15% 34% 27% 5%	611
March	1st to 10th	Night	21% 14% 33% 29% 3	720
	11th to 20th	Night	21% 15% 31% 27% 6%	720
	21st to end	Night	22% 11% 30% 25% 10% 1	792
April	1st to 10th	Night	24% 14% 30% 28% 5%	720
	11th to 20th	Night	20% 13% 31% 29% 7%	664
	21st to end	Night	28% 13% 26% 27% 7%	540
May	1st to 10th	Night	26% 10% 26% 29% 7% 1	540
	11th to 20th	Night	20% 10% 30% 30% 9%	449
	21st to end	Night	19% 7% 23% 38% 13% 1	389
June	1st to 10th	Night	22% 7% 25% 34% 11% 1	360
	11th to 20th	Night	21% 6% 22% 37% 14%	360
	21st to end	Night	20% 3 22% 41% 13% 1	360
July	1st to 10th	Night	17% 3 19% 42% 19% 1	350
	11th to 20th	Night	15% 1 18% 42% 21% 2	348
	21st to end	Night	14% 2 16% 47% 19% 1	394
August	1st to 10th	Night	16% 2 18% 42% 21% 1	446
	11th to 20th	Night	16% 5% 23% 37% 17% 2	532
	21st to end	Night	16% 4 18% 38% 21% 3	759
September	1st to 10th	Night	14% 4 22% 38% 20% 2	720
	11th to 20th	Night	18% 6% 21% 30% 20% 5%	720
	21st to end	Night	17% 7% 24% 31% 17% 3	720
October	1st to 10th	Night	23% 8% 21% 30% 16% 2	720
	11th to 20th	Night	20% 9% 28% 29% 13% 1	720
	21st to end	Night	29% 9% 27% 28% 7%	792
November	1st to 10th	Night	19% 11% 29% 31% 9% 1	740
	11th to 20th	Night	21% 14% 28% 27% 8% 1	760
	21st to end	Night	21% 16% 27% 29% 6% 1	760
December	1st to 10th	Night	24% 11% 36% 23% 5% 1	760
	11th to 20th	Night	23% 15% 28% 30% 3	760
	21st to end	Night	23% 13% 32% 29% 3	836

Page generated at 2024-02-22 06:05:43. Version ac07

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