Falling Waters
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Falling Waters clear sky chart from 2005-11-06 to 2024-01-15.

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	14% 6% 3 5% 5% 3 5% 5% 6% 8% 40%	74679
	Night	14% 6% 3 5% 5% 3 5% 5% 6% 7% 42%	75097
Transparency	Day	41% 7% 13% 22% 15% 2	74390
	Night	40% 7% 12% 23% 16% 3	74905
Seeing	Day	20% 13% 24% 22% 15% 6%	13757
	Night	18% 11% 27% 30% 13% 1	23413

By Month

Percentage Cloud Cover SE (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% 6% 3 5% 7% 4 5% 5% 6% 8% 38%	1583
	11th to 20th	Day	14% 8% 3 6% 6% 3 5% 6% 6% 8% 36%	1656
	21st to end	Day	15% 8% 3 6% 7% 3 5% 4 5% 6% 38%	1782
February	1st to 10th	Day	15% 9% 3 8% 6% 3 5% 5% 5% 7% 35%	1620
	11th to 20th	Day	14% 7% 3 7% 6% 3 6% 3 5% 6% 38%	1575
	21st to end	Day	17% 9% 4 7% 5% 2 5% 5% 3 5% 38%	1481
March	1st to 10th	Day	12% 6% 2 5% 5% 3 4 4 4 7% 47%	1980
	11th to 20th	Day	17% 7% 3 5% 5% 3 6% 4 6% 7% 38%	1980
	21st to end	Day	17% 7% 3 6% 6% 3 5% 5% 5% 6% 37%	2182
April	1st to 10th	Day	12% 7% 3 6% 5% 3 5% 5% 7% 8% 39%	2160
	11th to 20th	Day	14% 5% 2 6% 4 4 4 5% 5% 8% 43%	2134
	21st to end	Day	19% 6% 3 4 4 3 5% 5% 5% 6% 40%	2189
May	1st to 10th	Day	16% 7% 3 5% 5% 3 5% 6% 6% 9% 35%	2340
	11th to 20th	Day	19% 5% 3 5% 5% 3 6% 5% 5% 8% 36%	2384
	21st to end	Day	14% 6% 2 5% 5% 3 5% 5% 6% 8% 40%	2725
June	1st to 10th	Day	12% 5% 2 4 5% 3 5% 5% 7% 10% 43%	2520
	11th to 20th	Day	10% 5% 2 6% 6% 3 7% 7% 7% 10% 38%	2520
	21st to end	Day	10% 3 2 5% 5% 3 6% 5% 6% 10% 45%	2520
July	1st to 10th	Day	8% 4 2 5% 6% 3 5% 6% 7% 10% 42%	2520
	11th to 20th	Day	6% 5% 2 5% 5% 4 6% 6% 7% 11% 44%	2418
	21st to end	Day	9% 6% 3 6% 5% 4 6% 6% 7% 9% 38%	2547
August	1st to 10th	Day	9% 5% 2 6% 7% 4 7% 7% 8% 10% 37%	2327
	11th to 20th	Day	10% 6% 2 5% 5% 3 5% 5% 7% 9% 42%	2259
	21st to end	Day	11% 4 2 5% 5% 3 5% 5% 6% 9% 44%	2376
September	1st to 10th	Day	16% 5% 2 5% 4 3 4 4 5% 8% 44%	2160
	11th to 20th	Day	11% 5% 2 5% 4 3 4 4 6% 8% 48%	2143
	21st to end	Day	18% 7% 3 6% 4 3 4 4 5% 7% 40%	1886
October	1st to 10th	Day	16% 5% 2 5% 4 3 4 4 4 7% 46%	1800
	11th to 20th	Day	17% 4 2 4 5% 2 4 4 6% 6% 45%	1800
	21st to end	Day	15% 6% 2 5% 4 3 4 4 5% 6% 46%	1980
November	1st to 10th	Day	12% 6% 2 4 4 2 3 4 6% 7% 50%	1790
	11th to 20th	Day	16% 5% 2 4 5% 2 4 4 6% 7% 46%	1620
	21st to end	Day	16% 6% 3 5% 5% 4 5% 4 5% 7% 42%	1520
December	1st to 10th	Day	17% 10% 3 6% 5% 2 4 5% 7% 8% 33%	1520
	11th to 20th	Day	17% 5% 3 5% 6% 4 6% 4 6% 7% 39%	1910
	21st to end	Day	17% 6% 3 6% 7% 6% 6% 7% 7% 7% 29%	2772
January	1st to 10th	Night	13% 8% 3 5% 6% 3 4 4 6% 7% 40%	2578
	11th to 20th	Night	16% 8% 4 6% 5% 2 5% 5% 6% 7% 36%	2393
	21st to end	Night	15% 7% 3 6% 5% 3 4 4 6% 7% 39%	2574
February	1st to 10th	Night	16% 6% 4 6% 4 3 4 4 6% 8% 38%	2340
	11th to 20th	Night	16% 8% 3 6% 5% 3 4 5% 5% 6% 38%	2269
	21st to end	Night	17% 9% 3 6% 6% 3 5% 4 4 7% 35%	1772
March	1st to 10th	Night	12% 5% 2 5% 5% 3 5% 4 5% 7% 46%	1980
	11th to 20th	Night	18% 6% 2 5% 4 3 5% 5% 5% 7% 40%	1980
	21st to end	Night	15% 6% 3 7% 5% 3 6% 4 5% 6% 41%	2173
April	1st to 10th	Night	15% 7% 3 6% 6% 3 4 5% 5% 5% 39%	1800
	11th to 20th	Night	13% 5% 2 6% 5% 3 5% 4 6% 8% 44%	1775
	21st to end	Night	18% 4 2 4 4 3 4 5% 5% 7% 43%	1786
May	1st to 10th	Night	16% 6% 3 6% 5% 3 5% 4 7% 7% 39%	1620
	11th to 20th	Night	16% 6% 3 5% 5% 3 5% 6% 6% 8% 38%	1509
	21st to end	Night	13% 5% 2 5% 5% 3 5% 6% 6% 10% 41%	1550
June	1st to 10th	Night	11% 4 2 4 4 3 4 5% 7% 8% 48%	1440
	11th to 20th	Night	11% 5% 1 6% 6% 4 5% 5% 8% 9% 40%	1440
	21st to end	Night	9% 4 2 4 6% 3 5% 5% 8% 10% 45%	1440
July	1st to 10th	Night	10% 4 2 6% 5% 4 5% 6% 7% 9% 42%	1440
	11th to 20th	Night	5% 4 2 4 6% 3 6% 6% 7% 10% 46%	1538
	21st to end	Night	8% 4 2 4 5% 3 7% 6% 10% 12% 41%	1771
August	1st to 10th	Night	8% 4 3 6% 8% 3 6% 6% 7% 8% 41%	1611
	11th to 20th	Night	9% 5% 3 7% 6% 3 5% 5% 6% 7% 43%	1624
	21st to end	Night	11% 4 2 5% 5% 3 5% 5% 7% 9% 44%	1980
September	1st to 10th	Night	15% 5% 2 4 5% 3 4 5% 6% 6% 45%	1800
	11th to 20th	Night	10% 8% 3 5% 4 3 3 3 4 6% 51%	1813
	21st to end	Night	17% 7% 2 4 4 3 4 5% 5% 6% 43%	2073
October	1st to 10th	Night	19% 6% 2 4 4 3 4 5% 4 6% 44%	2160
	11th to 20th	Night	14% 5% 2 4 4 3 3 3 6% 6% 49%	2160
	21st to end	Night	16% 6% 2 4 4 2 3 4 5% 6% 48%	2376
November	1st to 10th	Night	10% 5% 2 4 4 2 4 4 4 7% 53%	2287
	11th to 20th	Night	14% 6% 3 4 4 3 4 4 5% 7% 46%	2556
	21st to end	Night	14% 5% 3 5% 5% 3 5% 5% 6% 7% 43%	2660
December	1st to 10th	Night	16% 8% 3 6% 6% 3 4 6% 5% 7% 38%	2660
	11th to 20th	Night	17% 6% 2 5% 5% 3 5% 5% 5% 7% 39%	3285
	21st to end	Night	17% 7% 3 5% 5% 4 6% 6% 7% 9% 31%	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	43% 7% 10% 24% 14% 2	1584
	11th to 20th	Day	46% 6% 14% 21% 12% 2	1656
	21st to end	Day	48% 4 12% 21% 13% 2	1782
February	1st to 10th	Day	48% 7% 12% 22% 10% 2	1620
	11th to 20th	Day	47% 5% 11% 24% 11% 2	1584
	21st to end	Day	49% 4 11% 20% 13% 3	1481
March	1st to 10th	Day	38% 5% 13% 25% 18% 2	1980
	11th to 20th	Day	45% 5% 11% 17% 17% 5%	1980
	21st to end	Day	48% 6% 10% 19% 15% 3	2182
April	1st to 10th	Day	42% 7% 12% 18% 17% 4	2160
	11th to 20th	Day	39% 5% 12% 21% 18% 5%	2134
	21st to end	Day	44% 6% 10% 21% 16% 3	2189
May	1st to 10th	Day	44% 8% 13% 18% 15% 2	2340
	11th to 20th	Day	46% 7% 11% 19% 13% 3	2388
	21st to end	Day	40% 7% 15% 24% 12% 1	2725
June	1st to 10th	Day	35% 8% 15% 24% 16% 1	2520
	11th to 20th	Day	39% 11% 14% 20% 14% 2	2520
	21st to end	Day	33% 9% 16% 26% 15% 1	2520
July	1st to 10th	Day	36% 10% 13% 23% 15% 3	2450
	11th to 20th	Day	32% 9% 14% 24% 17% 3	2344
	21st to end	Day	39% 10% 11% 21% 16% 3	2405
August	1st to 10th	Day	39% 10% 14% 25% 12%	2314
	11th to 20th	Day	38% 8% 14% 22% 15% 2	2259
	21st to end	Day	36% 8% 15% 24% 14% 3	2376
September	1st to 10th	Day	40% 7% 12% 19% 20% 4	2160
	11th to 20th	Day	33% 6% 11% 26% 21% 3	2143
	21st to end	Day	45% 5% 9% 20% 20% 2	1886
October	1st to 10th	Day	39% 5% 12% 24% 16% 3	1800
	11th to 20th	Day	38% 6% 11% 25% 19% 1	1800
	21st to end	Day	38% 5% 11% 24% 19% 3	1980
November	1st to 10th	Day	33% 5% 13% 25% 20% 4	1790
	11th to 20th	Day	38% 5% 11% 22% 21% 3	1620
	21st to end	Day	41% 6% 12% 27% 13% 1	1520
December	1st to 10th	Day	47% 7% 14% 22% 9% 1	1520
	11th to 20th	Day	44% 6% 12% 28% 8% 2	1906
	21st to end	Day	48% 9% 17% 17% 10%	2772
January	1st to 10th	Night	42% 6% 10% 23% 15% 3	2578
	11th to 20th	Night	46% 6% 15% 21% 11% 1	2393
	21st to end	Night	44% 5% 12% 25% 13% 2	2574
February	1st to 10th	Night	43% 6% 13% 24% 12% 2	2340
	11th to 20th	Night	46% 4 12% 20% 16% 3	2271
	21st to end	Night	49% 5% 11% 19% 12% 5%	1772
March	1st to 10th	Night	38% 5% 12% 26% 17% 2	1980
	11th to 20th	Night	42% 5% 11% 22% 17% 3	1980
	21st to end	Night	44% 5% 12% 20% 15% 4	2173
April	1st to 10th	Night	45% 6% 10% 19% 16% 4	1800
	11th to 20th	Night	37% 7% 11% 21% 18% 6%	1775
	21st to end	Night	40% 6% 12% 24% 14% 4	1786
May	1st to 10th	Night	43% 7% 10% 23% 13% 4	1620
	11th to 20th	Night	43% 8% 11% 18% 17% 2	1510
	21st to end	Night	37% 9% 15% 25% 12% 1	1551
June	1st to 10th	Night	33% 9% 10% 26% 18% 3	1440
	11th to 20th	Night	38% 9% 12% 25% 13% 2	1440
	21st to end	Night	32% 11% 13% 25% 17% 2	1440
July	1st to 10th	Night	38% 11% 14% 19% 13% 5%	1400
	11th to 20th	Night	31% 10% 15% 24% 18% 3	1489
	21st to end	Night	30% 11% 19% 22% 16% 2	1672
August	1st to 10th	Night	37% 10% 15% 23% 14% 1	1600
	11th to 20th	Night	38% 9% 14% 21% 17% 1	1624
	21st to end	Night	35% 9% 13% 24% 16% 3	1980
September	1st to 10th	Night	39% 8% 11% 20% 19% 4	1800
	11th to 20th	Night	34% 5% 8% 27% 23% 2	1813
	21st to end	Night	41% 7% 11% 20% 18% 2	2073
October	1st to 10th	Night	41% 5% 11% 23% 18% 2	2160
	11th to 20th	Night	34% 5% 11% 27% 20% 2	2160
	21st to end	Night	36% 5% 10% 26% 20% 2	2376
November	1st to 10th	Night	32% 5% 11% 27% 21% 4	2287
	11th to 20th	Night	38% 5% 9% 24% 20% 5%	2556
	21st to end	Night	39% 6% 12% 24% 17% 2	2660
December	1st to 10th	Night	45% 7% 11% 25% 12% 1	2660
	11th to 20th	Night	43% 5% 12% 23% 15% 2	3288
	21st to end	Night	45% 9% 16% 19% 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	31% 25% 26% 14% 4	211
	11th to 20th	Day	33% 25% 25% 13% 4	252
	21st to end	Day	28% 32% 23% 11% 3 1	264
February	1st to 10th	Day	29% 28% 30% 10% 3	240
	11th to 20th	Day	38% 24% 31% 7%	242
	21st to end	Day	33% 18% 27% 20% 2	346
March	1st to 10th	Day	26% 21% 25% 25% 2	420
	11th to 20th	Day	26% 21% 30% 16% 6% 1	420
	21st to end	Day	26% 18% 31% 18% 6% 1	462
April	1st to 10th	Day	23% 22% 25% 20% 8% 2	420
	11th to 20th	Day	18% 16% 32% 16% 13% 6%	412
	21st to end	Day	30% 15% 26% 18% 10% 2	420
May	1st to 10th	Day	25% 17% 26% 17% 11% 4	423
	11th to 20th	Day	23% 14% 25% 20% 16% 3	447
	21st to end	Day	18% 8% 21% 24% 20% 10%	485
June	1st to 10th	Day	15% 10% 26% 23% 19% 8%	450
	11th to 20th	Day	14% 9% 27% 25% 18% 7%	450
	21st to end	Day	11% 7% 26% 31% 19% 6%	450
July	1st to 10th	Day	12% 2 19% 25% 27% 14%	445
	11th to 20th	Day	7% 3 19% 27% 32% 11%	444
	21st to end	Day	12% 5% 21% 29% 25% 9%	488
August	1st to 10th	Day	13% 3 19% 24% 26% 15%	446
	11th to 20th	Day	13% 4 17% 28% 24% 13%	439
	21st to end	Day	11% 3 19% 29% 24% 15%	495
September	1st to 10th	Day	18% 6% 18% 24% 22% 13%	450
	11th to 20th	Day	15% 4 18% 29% 23% 11%	450
	21st to end	Day	22% 10% 21% 24% 19% 4	450
October	1st to 10th	Day	21% 5% 19% 25% 24% 5%	450
	11th to 20th	Day	17% 14% 25% 27% 14% 3	450
	21st to end	Day	19% 16% 28% 24% 11% 2	495
November	1st to 10th	Day	17% 14% 27% 24% 16% 3	423
	11th to 20th	Day	25% 13% 26% 23% 10% 3	280
	21st to end	Day	23% 16% 28% 25% 6% 2	180
December	1st to 10th	Day	28% 17% 29% 19% 6% 1	180
	11th to 20th	Day	24% 24% 26% 19% 6%	180
	21st to end	Day	23% 19% 28% 20% 9% 1	198
January	1st to 10th	Night	18% 21% 35% 23% 3	760
	11th to 20th	Night	25% 15% 29% 28% 4	737
	21st to end	Night	20% 19% 35% 24% 2	792
February	1st to 10th	Night	20% 20% 30% 28% 2	720
	11th to 20th	Night	23% 22% 34% 20% 1	703
	21st to end	Night	26% 20% 33% 19% 3	592
March	1st to 10th	Night	20% 17% 36% 24% 3	720
	11th to 20th	Night	24% 19% 28% 22% 6%	720
	21st to end	Night	18% 15% 38% 23% 4 1	792
April	1st to 10th	Night	21% 19% 32% 23% 5%	720
	11th to 20th	Night	17% 13% 31% 29% 9%	711
	21st to end	Night	22% 12% 27% 32% 7%	706
May	1st to 10th	Night	19% 8% 27% 33% 13% 1	540
	11th to 20th	Night	20% 5% 26% 35% 12% 1	448
	21st to end	Night	16% 4 22% 37% 20% 2	389
June	1st to 10th	Night	11% 2 25% 36% 24% 1	360
	11th to 20th	Night	11% 5% 21% 40% 21% 2	360
	21st to end	Night	10% 2 21% 47% 19% 1	360
July	1st to 10th	Night	12% 2 16% 36% 30% 4	350
	11th to 20th	Night	7% 2 13% 38% 36% 5%	445
	21st to end	Night	8% 3 14% 38% 33% 3	591
August	1st to 10th	Night	10% 3 12% 42% 30% 2	537
	11th to 20th	Night	11% 4 12% 37% 32% 3	560
	21st to end	Night	12% 2 15% 40% 27% 4	792
September	1st to 10th	Night	17% 3 16% 33% 28% 4	720
	11th to 20th	Night	14% 4 17% 33% 28% 3	720
	21st to end	Night	21% 4 21% 32% 21% 2	720
October	1st to 10th	Night	22% 6% 19% 30% 20% 3	720
	11th to 20th	Night	17% 9% 27% 33% 13% 1	720
	21st to end	Night	20% 11% 29% 29% 10%	792
November	1st to 10th	Night	13% 9% 30% 37% 11% 1	740
	11th to 20th	Night	19% 16% 26% 30% 9%	760
	21st to end	Night	18% 13% 31% 31% 7%	760
December	1st to 10th	Night	21% 16% 33% 23% 7%	760
	11th to 20th	Night	19% 13% 35% 28% 4	760
	21st to end	Night	20% 13% 29% 34% 3	836

Page generated at 2024-01-11 22:33:47. Version ac07

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