Waterfall Creek Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Waterfall Creek Observatory 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	13% 7% 3 6% 5% 3 5% 5% 5% 7% 42%	78535
	Night	13% 7% 3 5% 5% 3 4 4 5% 6% 45%	80807
Transparency	Day	41% 5% 11% 24% 16% 3	78248
	Night	40% 5% 10% 24% 17% 3	80615
Seeing	Day	18% 11% 27% 25% 14% 4	14523
	Night	18% 12% 30% 25% 12% 2	24535

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	12% 13% 4 7% 4 3 4 4 4 5% 41%	2600
	11th to 20th	Day	13% 9% 4 6% 5% 3 4 3 3 6% 44%	2850
	21st to end	Day	22% 9% 3 6% 4 2 3 3 4 5% 39%	3135
February	1st to 10th	Day	16% 10% 4 8% 5% 4 4 4 4 6% 37%	1710
	11th to 20th	Day	15% 8% 3 6% 5% 3 4 4 4 7% 40%	1807
	21st to end	Day	16% 10% 3 5% 6% 3 5% 4 5% 6% 37%	1520
March	1st to 10th	Day	14% 9% 3 6% 4 2 4 4 4 5% 43%	1890
	11th to 20th	Day	20% 10% 4 5% 5% 3 5% 3 5% 5% 36%	1980
	21st to end	Day	20% 10% 4 7% 6% 4 5% 5% 5% 5% 30%	2251
April	1st to 10th	Day	11% 6% 3 5% 6% 3 4 4 5% 8% 45%	2160
	11th to 20th	Day	17% 8% 3 6% 5% 2 4 4 5% 6% 38%	2134
	21st to end	Day	20% 7% 4 6% 5% 4 5% 4 5% 6% 37%	2160
May	1st to 10th	Day	17% 7% 4 5% 5% 3 5% 6% 6% 7% 36%	2160
	11th to 20th	Day	16% 6% 2 5% 5% 3 4 4 5% 8% 41%	2409
	21st to end	Day	11% 7% 3 7% 7% 4 6% 6% 6% 8% 35%	2725
June	1st to 10th	Day	9% 5% 3 5% 7% 3 6% 6% 6% 8% 43%	2520
	11th to 20th	Day	6% 4 2 4 5% 4 5% 6% 7% 9% 48%	2520
	21st to end	Day	5% 3 2 4 5% 4 5% 6% 8% 9% 49%	2520
July	1st to 10th	Day	10% 4 2 5% 5% 4 6% 7% 8% 9% 41%	2520
	11th to 20th	Day	4 3 2 4 5% 4 6% 6% 7% 10% 48%	2447
	21st to end	Day	6% 5% 2 7% 7% 4 6% 6% 7% 10% 41%	2546
August	1st to 10th	Day	8% 4 2 5% 6% 3 7% 6% 8% 10% 41%	2328
	11th to 20th	Day	11% 5% 2 6% 6% 4 6% 6% 6% 9% 39%	2134
	21st to end	Day	10% 4 2 5% 5% 3 5% 6% 5% 9% 45%	2376
September	1st to 10th	Day	13% 5% 2 5% 3 3 4 5% 5% 7% 49%	2160
	11th to 20th	Day	10% 5% 2 5% 5% 2 4 4 6% 7% 49%	2160
	21st to end	Day	9% 5% 2 4 4 2 4 4 5% 7% 53%	1930
October	1st to 10th	Day	9% 4 2 5% 4 2 3 4 5% 6% 55%	1800
	11th to 20th	Day	14% 6% 2 5% 4 2 3 3 3 5% 52%	1800
	21st to end	Day	19% 8% 2 4 4 2 3 4 3 5% 46%	1980
November	1st to 10th	Day	12% 6% 2 4 4 2 4 4 4 5% 54%	1736
	11th to 20th	Day	12% 8% 3 5% 4 3 3 3 5% 7% 47%	1710
	21st to end	Day	16% 9% 4 5% 4 3 3 4 3 5% 44%	1636
December	1st to 10th	Day	14% 8% 3 6% 5% 3 3 5% 5% 7% 40%	1520
	11th to 20th	Day	14% 9% 5% 7% 6% 3 5% 4 3 4 39%	1918
	21st to end	Day	14% 17% 5% 7% 5% 3 4 4 4 5% 31%	2783
January	1st to 10th	Night	14% 9% 5% 8% 6% 3 4 4 4 5% 38%	4352
	11th to 20th	Night	13% 8% 3 7% 8% 3 4 5% 5% 6% 37%	4120
	21st to end	Night	21% 12% 5% 6% 5% 2 3 4 4 5% 35%	4532
February	1st to 10th	Night	17% 9% 3 7% 4 3 4 3 4 7% 38%	2470
	11th to 20th	Night	15% 7% 4 7% 5% 3 3 4 4 7% 44%	2257
	21st to end	Night	17% 9% 4 6% 5% 3 4 4 3 5% 41%	1831
March	1st to 10th	Night	16% 9% 3 5% 4 2 3 3 5% 5% 44%	2084
	11th to 20th	Night	19% 9% 3 7% 4 3 4 4 4 5% 39%	1980
	21st to end	Night	19% 10% 4 6% 6% 2 4 4 5% 6% 33%	2103
April	1st to 10th	Night	10% 6% 2 4 4 3 3 4 6% 8% 51%	1800
	11th to 20th	Night	13% 7% 3 5% 6% 3 4 3 4 7% 44%	1775
	21st to end	Night	19% 7% 3 5% 5% 3 4 3 4 7% 41%	1800
May	1st to 10th	Night	15% 6% 2 4 4 2 4 4 5% 7% 47%	1800
	11th to 20th	Night	16% 6% 3 5% 4 3 4 3 4 7% 45%	1479
	21st to end	Night	10% 7% 3 6% 7% 3 5% 5% 6% 9% 37%	1551
June	1st to 10th	Night	8% 4 2 5% 5% 3 5% 5% 6% 10% 47%	1440
	11th to 20th	Night	6% 3 2 3 3 2 3 4 5% 11% 57%	1440
	21st to end	Night	3 2 1 3 3 3 4 5% 6% 10% 58%	1440
July	1st to 10th	Night	8% 4 2 3 4 4 5% 4 6% 8% 52%	1440
	11th to 20th	Night	5% 4 1 3 3 3 4 4 6% 9% 58%	1508
	21st to end	Night	5% 5% 2 4 5% 3 5% 5% 7% 9% 50%	1772
August	1st to 10th	Night	5% 4 2 4 5% 2 5% 7% 7% 8% 50%	1611
	11th to 20th	Night	7% 4 1 3 4 3 4 5% 6% 9% 54%	1767
	21st to end	Night	7% 4 2 4 4 3 3 6% 5% 7% 55%	1980
September	1st to 10th	Night	10% 5% 3 3 4 3 4 4 5% 7% 53%	1800
	11th to 20th	Night	9% 5% 2 4 4 2 4 5% 5% 7% 54%	1800
	21st to end	Night	9% 5% 1 3 3 2 4 4 5% 6% 57%	2007
October	1st to 10th	Night	7% 4 1 3 4 2 3 4 4 6% 62%	2160
	11th to 20th	Night	14% 6% 2 3 4 2 3 3 4 4 54%	2160
	21st to end	Night	20% 6% 2 4 3 2 3 3 3 4 48%	2376
November	1st to 10th	Night	10% 6% 2 4 3 2 3 4 4 6% 57%	2338
	11th to 20th	Night	14% 6% 2 5% 4 2 4 4 4 6% 49%	2470
	21st to end	Night	18% 9% 3 5% 4 2 3 2 4 5% 45%	2541
December	1st to 10th	Night	17% 9% 2 5% 5% 3 4 4 4 7% 39%	2660
	11th to 20th	Night	16% 8% 5% 6% 5% 3 4 4 3 6% 41%	3279
	21st to end	Night	17% 17% 6% 8% 5% 3 4 4 4 5% 27%	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	45% 4 7% 28% 13% 2	2601
	11th to 20th	Day	44% 4 8% 25% 16% 3	2850
	21st to end	Day	50% 3 8% 17% 16% 6%	3135
February	1st to 10th	Day	49% 3 10% 22% 13% 2	1710
	11th to 20th	Day	44% 5% 12% 20% 14% 5%	1817
	21st to end	Day	48% 4 8% 23% 11% 7%	1520
March	1st to 10th	Day	44% 4 8% 22% 17% 5%	1890
	11th to 20th	Day	50% 5% 8% 19% 14% 3	1980
	21st to end	Day	55% 5% 11% 19% 9% 1	2251
April	1st to 10th	Day	37% 4 12% 26% 20% 1	2160
	11th to 20th	Day	47% 4 10% 20% 17% 3	2134
	21st to end	Day	49% 5% 10% 21% 14% 1	2160
May	1st to 10th	Day	46% 7% 13% 23% 11% 1	2160
	11th to 20th	Day	42% 6% 12% 23% 15% 2	2413
	21st to end	Day	45% 7% 13% 21% 12% 1	2725
June	1st to 10th	Day	37% 7% 13% 26% 15% 2	2520
	11th to 20th	Day	30% 7% 13% 29% 19% 3	2520
	21st to end	Day	28% 7% 18% 26% 16% 5%	2520
July	1st to 10th	Day	36% 7% 15% 26% 12% 4	2451
	11th to 20th	Day	29% 8% 14% 28% 18% 4	2372
	21st to end	Day	36% 8% 14% 30% 11% 1	2405
August	1st to 10th	Day	35% 9% 15% 26% 15%	2314
	11th to 20th	Day	39% 8% 13% 25% 13% 1	2134
	21st to end	Day	35% 7% 14% 24% 15% 6%	2376
September	1st to 10th	Day	34% 6% 11% 29% 15% 5%	2160
	11th to 20th	Day	34% 5% 8% 26% 25% 2	2160
	21st to end	Day	32% 5% 7% 29% 26% 3	1930
October	1st to 10th	Day	30% 5% 10% 25% 26% 3	1800
	11th to 20th	Day	36% 3 6% 26% 23% 6%	1800
	21st to end	Day	42% 3 6% 25% 18% 5%	1980
November	1st to 10th	Day	33% 4 9% 25% 21% 7%	1736
	11th to 20th	Day	38% 3 7% 23% 22% 7%	1710
	21st to end	Day	44% 3 8% 25% 18% 2	1636
December	1st to 10th	Day	44% 4 9% 27% 14% 2	1520
	11th to 20th	Day	49% 4 6% 19% 21% 1	1915
	21st to end	Day	54% 6% 9% 15% 13% 2	2783
January	1st to 10th	Night	47% 5% 8% 23% 14% 2	4352
	11th to 20th	Night	45% 7% 8% 25% 13% 2	4120
	21st to end	Night	53% 4 8% 21% 13% 1	4532
February	1st to 10th	Night	48% 4 10% 22% 15% 2	2470
	11th to 20th	Night	43% 3 12% 22% 17% 3	2258
	21st to end	Night	47% 3 7% 23% 16% 4	1831
March	1st to 10th	Night	43% 3 8% 21% 18% 6%	2084
	11th to 20th	Night	49% 4 9% 21% 14% 3	1980
	21st to end	Night	53% 4 11% 21% 10% 1	2103
April	1st to 10th	Night	33% 4 13% 27% 21% 3	1800
	11th to 20th	Night	41% 4 11% 24% 15% 5%	1775
	21st to end	Night	45% 4 9% 25% 16% 1	1800
May	1st to 10th	Night	37% 6% 15% 24% 17% 2	1800
	11th to 20th	Night	40% 6% 13% 21% 18% 2	1480
	21st to end	Night	43% 6% 14% 20% 14% 3	1552
June	1st to 10th	Night	31% 7% 15% 25% 20% 1	1440
	11th to 20th	Night	22% 5% 13% 36% 20% 4	1440
	21st to end	Night	20% 8% 16% 32% 18% 7%	1440
July	1st to 10th	Night	30% 7% 17% 26% 15% 5%	1400
	11th to 20th	Night	23% 6% 17% 30% 21% 4	1460
	21st to end	Night	28% 8% 14% 34% 16% 1	1673
August	1st to 10th	Night	28% 8% 16% 32% 13% 2	1601
	11th to 20th	Night	26% 7% 16% 29% 19% 2	1767
	21st to end	Night	28% 6% 15% 27% 19% 5%	1980
September	1st to 10th	Night	31% 5% 10% 30% 19% 5%	1800
	11th to 20th	Night	29% 6% 11% 27% 26% 2	1800
	21st to end	Night	28% 5% 9% 26% 28% 4	2007
October	1st to 10th	Night	24% 4 11% 29% 27% 5%	2160
	11th to 20th	Night	34% 3 7% 26% 24% 5%	2160
	21st to end	Night	41% 3 8% 22% 21% 5%	2376
November	1st to 10th	Night	30% 4 11% 27% 22% 6%	2338
	11th to 20th	Night	37% 3 6% 23% 23% 7%	2470
	21st to end	Night	44% 3 6% 25% 21% 2	2541
December	1st to 10th	Night	44% 5% 10% 23% 17% 2	2660
	11th to 20th	Night	46% 3 8% 24% 18% 2	3281
	21st to end	Night	59% 6% 7% 16% 9% 2	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	30% 21% 34% 11% 3	270
	11th to 20th	Day	33% 24% 34% 8% 1	270
	21st to end	Day	25% 30% 33% 12% 1	297
February	1st to 10th	Day	29% 25% 33% 11% 2	270
	11th to 20th	Day	33% 24% 32% 9% 1 1	270
	21st to end	Day	37% 23% 31% 7% 1	210
March	1st to 10th	Day	28% 22% 39% 11% 1	240
	11th to 20th	Day	38% 15% 34% 11% 3	240
	21st to end	Day	35% 19% 35% 10% 2	337
April	1st to 10th	Day	22% 20% 36% 17% 4 1	420
	11th to 20th	Day	27% 20% 29% 18% 5% 1	412
	21st to end	Day	27% 18% 32% 18% 3 1	420
May	1st to 10th	Day	22% 19% 35% 19% 5% 1	423
	11th to 20th	Day	20% 13% 31% 22% 11% 2	609
	21st to end	Day	15% 8% 34% 26% 13% 4	679
June	1st to 10th	Day	11% 6% 23% 31% 24% 5%	630
	11th to 20th	Day	8% 3 25% 39% 21% 4	630
	21st to end	Day	5% 7% 33% 31% 19% 4	630
July	1st to 10th	Day	13% 2 16% 31% 30% 8%	621
	11th to 20th	Day	6% 2 20% 36% 29% 6%	618
	21st to end	Day	8% 2 18% 36% 28% 7%	684
August	1st to 10th	Day	11% 2 15% 41% 25% 6%	626
	11th to 20th	Day	15% 2 17% 31% 28% 7%	448
	21st to end	Day	14% 2 13% 30% 29% 12%	495
September	1st to 10th	Day	14% 4 16% 34% 24% 8%	450
	11th to 20th	Day	9% 3 21% 33% 24% 10%	450
	21st to end	Day	12% 10% 22% 30% 18% 8%	390
October	1st to 10th	Day	13% 11% 33% 31% 9% 3	270
	11th to 20th	Day	24% 13% 40% 18% 4	270
	21st to end	Day	35% 19% 27% 18% 2	297
November	1st to 10th	Day	15% 16% 38% 25% 4 2	270
	11th to 20th	Day	24% 17% 34% 17% 7%	270
	21st to end	Day	29% 17% 33% 16% 5% 1	270
December	1st to 10th	Day	21% 23% 33% 16% 5% 2	270
	11th to 20th	Day	28% 19% 36% 14% 3	270
	21st to end	Day	30% 24% 34% 9% 2 1	297
January	1st to 10th	Night	22% 23% 37% 16% 3	950
	11th to 20th	Night	26% 25% 33% 13% 3	950
	21st to end	Night	22% 22% 39% 16% 2	1045
February	1st to 10th	Night	25% 20% 36% 17% 1	950
	11th to 20th	Night	22% 22% 40% 15% 1	782
	21st to end	Night	26% 22% 35% 14% 2	611
March	1st to 10th	Night	26% 16% 36% 20% 2	644
	11th to 20th	Night	27% 12% 36% 21% 4	540
	21st to end	Night	25% 17% 34% 20% 4	594
April	1st to 10th	Night	15% 19% 39% 23% 4	540
	11th to 20th	Night	20% 16% 34% 24% 6%	533
	21st to end	Night	21% 13% 38% 21% 7%	540
May	1st to 10th	Night	18% 8% 37% 29% 8%	540
	11th to 20th	Night	19% 6% 34% 26% 14% 1	531
	21st to end	Night	13% 5% 28% 33% 17% 3	584
June	1st to 10th	Night	8% 4 20% 35% 30% 3	540
	11th to 20th	Night	6% 2 24% 44% 22% 2	540
	21st to end	Night	4 2 26% 39% 27% 3	540
July	1st to 10th	Night	9% 3 11% 36% 31% 10%	525
	11th to 20th	Night	7% 1 14% 41% 32% 5%	522
	21st to end	Night	7% 2 14% 41% 32% 4	591
August	1st to 10th	Night	7% 1 12% 41% 35% 4	537
	11th to 20th	Night	8% 1 15% 39% 32% 5%	534
	21st to end	Night	8% 13% 35% 36% 8%	594
September	1st to 10th	Night	12% 3 14% 37% 29% 5%	540
	11th to 20th	Night	11% 2 14% 37% 31% 6%	540
	21st to end	Night	12% 6% 24% 27% 27% 4	690
October	1st to 10th	Night	10% 4 31% 30% 23% 3	720
	11th to 20th	Night	18% 12% 35% 26% 9% 1	720
	21st to end	Night	26% 12% 33% 22% 6% 1	792
November	1st to 10th	Night	14% 13% 40% 25% 8% 1	740
	11th to 20th	Night	20% 16% 32% 25% 7% 1	760
	21st to end	Night	23% 17% 35% 20% 5%	831
December	1st to 10th	Night	25% 15% 37% 19% 4	950
	11th to 20th	Night	25% 14% 35% 21% 3	950
	21st to end	Night	28% 20% 33% 18% 2	1045

Page generated at 2024-02-22 05:05:46. Version ac07

Copyright 2024 Attilla Danko