Wever
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Wever 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% 8% 3 7% 6% 3 5% 5% 5% 7% 39%	78460
	Night	13% 9% 4 7% 5% 3 4 4 5% 6% 40%	80895
Transparency	Day	45% 5% 12% 23% 13% 2	78166
	Night	44% 4 12% 23% 14% 2	80710
Seeing	Day	16% 8% 27% 27% 16% 5%	14729
	Night	17% 8% 30% 31% 13% 1	24778

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% 11% 6% 14% 8% 4 5% 3 4 6% 26%	2527
	11th to 20th	Day	12% 11% 4 11% 9% 5% 8% 5% 6% 6% 23%	2662
	21st to end	Day	16% 17% 9% 12% 8% 3 4 4 3 4 20%	3135
February	1st to 10th	Day	14% 11% 6% 9% 8% 3 5% 4 4 6% 30%	1710
	11th to 20th	Day	13% 10% 4 7% 7% 3 5% 5% 5% 6% 36%	1738
	21st to end	Day	14% 12% 4 9% 6% 3 3 4 5% 6% 34%	1520
March	1st to 10th	Day	15% 10% 5% 7% 6% 3 4 4 4 6% 36%	1859
	11th to 20th	Day	14% 10% 4 6% 5% 3 4 5% 6% 7% 35%	1980
	21st to end	Day	20% 11% 4 8% 6% 3 4 4 5% 6% 28%	2263
April	1st to 10th	Day	15% 10% 4 7% 6% 2 3 4 4 8% 38%	2160
	11th to 20th	Day	16% 9% 3 6% 5% 3 5% 4 4 6% 39%	2134
	21st to end	Day	21% 8% 3 6% 7% 3 4 4 5% 6% 34%	2160
May	1st to 10th	Day	17% 7% 3 6% 6% 3 6% 5% 6% 7% 33%	2344
	11th to 20th	Day	18% 7% 3 6% 6% 3 4 5% 4 8% 36%	2479
	21st to end	Day	14% 7% 3 6% 6% 4 6% 5% 6% 8% 35%	2725
June	1st to 10th	Day	7% 4 3 5% 5% 3 5% 5% 7% 8% 46%	2520
	11th to 20th	Day	7% 6% 2 6% 6% 3 5% 5% 5% 8% 48%	2520
	21st to end	Day	10% 5% 2 6% 5% 4 5% 5% 8% 9% 41%	2520
July	1st to 10th	Day	8% 4 2 5% 4 4 4 5% 6% 10% 49%	2520
	11th to 20th	Day	7% 4 2 4 5% 3 6% 5% 8% 9% 47%	2520
	21st to end	Day	6% 5% 3 4 4 3 6% 5% 6% 10% 48%	2653
August	1st to 10th	Day	7% 4 2 5% 6% 3 6% 6% 8% 10% 42%	2328
	11th to 20th	Day	8% 5% 2 5% 6% 4 5% 5% 6% 9% 46%	2212
	21st to end	Day	7% 5% 2 5% 5% 3 4 5% 4 8% 52%	2376
September	1st to 10th	Day	11% 4 2 4 4 3 4 5% 6% 8% 48%	2160
	11th to 20th	Day	10% 3 2 4 3 3 3 5% 6% 8% 53%	2160
	21st to end	Day	8% 5% 2 4 4 3 5% 7% 5% 8% 50%	1922
October	1st to 10th	Day	13% 6% 2 5% 4 2 4 5% 4 6% 49%	1800
	11th to 20th	Day	16% 8% 3 5% 4 3 3 3 4 6% 44%	1800
	21st to end	Day	19% 8% 3 5% 4 2 3 4 4 6% 41%	1958
November	1st to 10th	Day	11% 6% 3 5% 4 2 3 4 4 8% 48%	1672
	11th to 20th	Day	17% 8% 4 6% 4 2 4 4 4 6% 40%	1682
	21st to end	Day	16% 11% 3 7% 6% 2 3 3 4 7% 38%	1520
December	1st to 10th	Day	14% 12% 4 8% 5% 4 5% 3 4 6% 35%	1520
	11th to 20th	Day	15% 10% 4 7% 5% 3 4 5% 5% 7% 35%	1918
	21st to end	Day	23% 17% 7% 11% 6% 3 4 4 4 4 19%	2783
January	1st to 10th	Night	13% 12% 8% 11% 6% 3 4 4 4 5% 30%	4428
	11th to 20th	Night	13% 16% 6% 10% 6% 4 6% 5% 7% 4 24%	4306
	21st to end	Night	19% 17% 6% 11% 6% 2 4 3 4 6% 22%	4532
February	1st to 10th	Night	14% 11% 5% 7% 6% 3 5% 3 4 6% 35%	2470
	11th to 20th	Night	13% 10% 4 6% 5% 3 4 5% 5% 7% 39%	2327
	21st to end	Night	15% 10% 4 7% 5% 3 3 3 4 5% 41%	1831
March	1st to 10th	Night	13% 9% 4 6% 5% 3 5% 3 4 5% 43%	2116
	11th to 20th	Night	15% 8% 4 6% 5% 3 4 4 5% 6% 40%	1980
	21st to end	Night	20% 10% 4 7% 7% 3 5% 4 5% 6% 28%	2093
April	1st to 10th	Night	13% 8% 3 6% 5% 3 4 5% 5% 7% 40%	1800
	11th to 20th	Night	16% 8% 3 6% 4 2 3 4 5% 6% 43%	1775
	21st to end	Night	18% 6% 2 6% 6% 3 5% 5% 4 7% 39%	1800
May	1st to 10th	Night	15% 6% 2 6% 5% 3 4 5% 7% 9% 38%	1612
	11th to 20th	Night	16% 5% 3 7% 4 3 4 4 4 7% 43%	1416
	21st to end	Night	11% 6% 2 5% 6% 4 5% 5% 6% 8% 42%	1551
June	1st to 10th	Night	8% 3 1 4 4 3 4 5% 5% 9% 52%	1440
	11th to 20th	Night	8% 6% 2 4 4 3 3 5% 6% 11% 49%	1440
	21st to end	Night	8% 4 2 6% 4 3 4 6% 6% 9% 48%	1440
July	1st to 10th	Night	7% 4 2 4 5% 3 4 5% 7% 9% 51%	1440
	11th to 20th	Night	4 4 2 4 4 2 4 5% 6% 10% 55%	1440
	21st to end	Night	6% 4 2 4 4 2 5% 5% 6% 9% 53%	1661
August	1st to 10th	Night	5% 4 1 4 4 3 4 5% 7% 10% 53%	1611
	11th to 20th	Night	7% 5% 1 5% 4 3 5% 4 5% 6% 54%	1688
	21st to end	Night	6% 4 2 4 4 3 3 4 5% 7% 60%	1980
September	1st to 10th	Night	12% 4 2 4 3 2 3 4 5% 7% 55%	1800
	11th to 20th	Night	9% 4 1 5% 4 3 4 5% 4 7% 54%	1800
	21st to end	Night	7% 3 2 5% 5% 3 4 5% 5% 8% 53%	2018
October	1st to 10th	Night	11% 5% 2 5% 4 3 3 3 5% 6% 54%	2160
	11th to 20th	Night	15% 5% 2 5% 4 2 3 3 5% 6% 50%	2160
	21st to end	Night	17% 7% 3 5% 5% 3 3 4 5% 5% 42%	2398
November	1st to 10th	Night	11% 5% 2 4 3 2 4 4 4 6% 55%	2406
	11th to 20th	Night	14% 8% 3 5% 4 2 4 5% 6% 7% 43%	2493
	21st to end	Night	16% 8% 3 7% 5% 3 4 4 4 5% 40%	2660
December	1st to 10th	Night	13% 10% 5% 7% 5% 3 4 4 5% 6% 37%	2660
	11th to 20th	Night	15% 8% 4 8% 5% 3 4 4 5% 5% 38%	3279
	21st to end	Night	21% 17% 7% 10% 7% 3 4 4 3 4 21%	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	58% 7% 11% 17% 7%	2528
	11th to 20th	Day	61% 5% 10% 18% 7%	2662
	21st to end	Day	68% 5% 9% 12% 6%	3135
February	1st to 10th	Day	55% 4 14% 18% 7% 1	1710
	11th to 20th	Day	48% 5% 12% 23% 11% 1	1747
	21st to end	Day	51% 5% 11% 22% 10% 1	1520
March	1st to 10th	Day	50% 4 13% 21% 10% 1	1859
	11th to 20th	Day	47% 5% 15% 22% 10% 1	1980
	21st to end	Day	56% 5% 11% 19% 7% 1	2263
April	1st to 10th	Day	47% 4 13% 24% 12% 1	2160
	11th to 20th	Day	47% 4 9% 26% 12% 2	2134
	21st to end	Day	51% 4 11% 20% 13% 2	2160
May	1st to 10th	Day	49% 7% 12% 22% 11% 1	2344
	11th to 20th	Day	48% 5% 11% 22% 13%	2483
	21st to end	Day	47% 7% 12% 18% 14% 2	2725
June	1st to 10th	Day	34% 7% 15% 27% 15% 2	2520
	11th to 20th	Day	35% 7% 10% 24% 22% 3	2520
	21st to end	Day	37% 8% 15% 23% 15% 2	2520
July	1st to 10th	Day	30% 7% 14% 30% 15% 4	2451
	11th to 20th	Day	32% 6% 16% 28% 15% 3	2445
	21st to end	Day	30% 6% 16% 30% 16% 1	2506
August	1st to 10th	Day	33% 8% 18% 28% 11% 1	2314
	11th to 20th	Day	34% 6% 13% 30% 15% 1	2212
	21st to end	Day	31% 5% 12% 29% 19% 4	2376
September	1st to 10th	Day	33% 6% 12% 27% 18% 5%	2160
	11th to 20th	Day	28% 5% 12% 31% 20% 5%	2160
	21st to end	Day	32% 5% 11% 31% 20% 2	1922
October	1st to 10th	Day	37% 5% 9% 26% 22% 1	1800
	11th to 20th	Day	42% 3 8% 26% 18% 2	1800
	21st to end	Day	45% 4 11% 23% 14% 2	1958
November	1st to 10th	Day	35% 4 15% 25% 17% 3	1672
	11th to 20th	Day	46% 4 10% 24% 14% 1	1682
	21st to end	Day	48% 3 14% 24% 10%	1520
December	1st to 10th	Day	52% 4 13% 21% 9% 1	1520
	11th to 20th	Day	49% 4 12% 24% 9% 2	1915
	21st to end	Day	70% 4 8% 12% 6% 1	2783
January	1st to 10th	Night	57% 4 10% 19% 9%	4428
	11th to 20th	Night	60% 3 11% 14% 10% 1	4306
	21st to end	Night	65% 3 10% 16% 6%	4532
February	1st to 10th	Night	51% 4 11% 21% 12% 1	2470
	11th to 20th	Night	45% 5% 11% 26% 12% 1	2328
	21st to end	Night	47% 4 8% 24% 14% 3	1831
March	1st to 10th	Night	45% 4 11% 27% 12% 1	2116
	11th to 20th	Night	45% 4 12% 23% 12% 3	1980
	21st to end	Night	58% 5% 11% 18% 7% 1	2093
April	1st to 10th	Night	43% 5% 11% 25% 14% 3	1800
	11th to 20th	Night	43% 3 10% 24% 16% 4	1775
	21st to end	Night	45% 5% 12% 20% 14% 4	1800
May	1st to 10th	Night	41% 7% 14% 23% 14% 1	1612
	11th to 20th	Night	41% 4 13% 23% 17% 2	1417
	21st to end	Night	39% 6% 14% 22% 17% 3	1552
June	1st to 10th	Night	29% 6% 16% 27% 18% 3	1440
	11th to 20th	Night	30% 6% 13% 24% 23% 4	1440
	21st to end	Night	33% 8% 14% 21% 20% 4	1440
July	1st to 10th	Night	29% 5% 14% 32% 16% 4	1400
	11th to 20th	Night	23% 5% 16% 33% 20% 3	1392
	21st to end	Night	26% 5% 14% 29% 22% 3	1569
August	1st to 10th	Night	25% 8% 17% 32% 15% 2	1601
	11th to 20th	Night	30% 6% 11% 31% 20% 3	1688
	21st to end	Night	24% 6% 13% 28% 22% 8%	1980
September	1st to 10th	Night	29% 4 12% 27% 23% 6%	1800
	11th to 20th	Night	30% 5% 12% 27% 20% 6%	1800
	21st to end	Night	28% 5% 10% 30% 24% 3	2018
October	1st to 10th	Night	33% 4 11% 24% 25% 4	2160
	11th to 20th	Night	35% 4 10% 27% 20% 4	2160
	21st to end	Night	44% 4 10% 22% 18% 2	2398
November	1st to 10th	Night	32% 4 14% 27% 20% 4	2406
	11th to 20th	Night	41% 4 12% 25% 17% 2	2493
	21st to end	Night	47% 3 11% 25% 13% 1	2660
December	1st to 10th	Night	48% 4 13% 24% 10% 1	2660
	11th to 20th	Night	48% 4 12% 26% 9% 1	3281
	21st to end	Night	68% 4 9% 13% 6% 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	23% 13% 33% 21% 9%	270
	11th to 20th	Day	23% 19% 38% 18% 2	270
	21st to end	Day	24% 14% 33% 23% 5%	297
February	1st to 10th	Day	23% 14% 38% 21% 4	270
	11th to 20th	Day	24% 18% 29% 21% 7% 1	270
	21st to end	Day	23% 13% 43% 19% 3	210
March	1st to 10th	Day	17% 21% 37% 22% 3	240
	11th to 20th	Day	25% 13% 34% 22% 6% 1	240
	21st to end	Day	36% 13% 30% 15% 5% 1	349
April	1st to 10th	Day	20% 14% 36% 22% 7% 1	420
	11th to 20th	Day	19% 15% 34% 20% 11% 1	412
	21st to end	Day	25% 9% 32% 23% 10% 2	420
May	1st to 10th	Day	22% 8% 33% 26% 8% 2	535
	11th to 20th	Day	20% 11% 29% 26% 12% 2	625
	21st to end	Day	16% 5% 29% 28% 15% 7%	679
June	1st to 10th	Day	7% 5% 23% 33% 23% 8%	630
	11th to 20th	Day	9% 3 26% 37% 20% 4	630
	21st to end	Day	11% 9% 29% 32% 15% 4	630
July	1st to 10th	Day	12% 2 14% 29% 29% 14%	621
	11th to 20th	Day	10% 3 20% 35% 25% 7%	618
	21st to end	Day	7% 1 17% 39% 28% 7%	684
August	1st to 10th	Day	8% 2 16% 36% 27% 11%	626
	11th to 20th	Day	8% 4 14% 31% 31% 11%	526
	21st to end	Day	7% 1 16% 31% 32% 12%	495
September	1st to 10th	Day	14% 4 17% 30% 27% 8%	450
	11th to 20th	Day	9% 2 17% 37% 25% 10%	450
	21st to end	Day	11% 7% 26% 24% 24% 7%	378
October	1st to 10th	Day	21% 5% 26% 30% 11% 7%	270
	11th to 20th	Day	20% 20% 31% 20% 9% 1	270
	21st to end	Day	31% 12% 31% 19% 6% 1	297
November	1st to 10th	Day	14% 8% 40% 26% 9% 3	270
	11th to 20th	Day	21% 14% 32% 22% 9% 2	270
	21st to end	Day	27% 9% 35% 23% 6%	270
December	1st to 10th	Day	18% 12% 38% 23% 7% 3	270
	11th to 20th	Day	20% 13% 37% 22% 7%	270
	21st to end	Day	26% 20% 36% 15% 3	297
January	1st to 10th	Night	17% 12% 40% 24% 7%	950
	11th to 20th	Night	19% 13% 38% 23% 6%	950
	21st to end	Night	20% 13% 35% 27% 4	1045
February	1st to 10th	Night	21% 11% 38% 25% 4	950
	11th to 20th	Night	18% 13% 36% 29% 4	853
	21st to end	Night	20% 13% 40% 22% 3	611
March	1st to 10th	Night	19% 12% 39% 25% 5%	676
	11th to 20th	Night	19% 11% 33% 29% 7%	540
	21st to end	Night	24% 12% 33% 25% 5% 1	594
April	1st to 10th	Night	19% 11% 38% 25% 6%	540
	11th to 20th	Night	20% 10% 32% 30% 7%	533
	21st to end	Night	22% 8% 31% 30% 8%	540
May	1st to 10th	Night	19% 6% 36% 29% 8% 1	540
	11th to 20th	Night	17% 6% 27% 37% 12% 1	531
	21st to end	Night	13% 4 25% 36% 20% 2	584
June	1st to 10th	Night	10% 2 21% 46% 19% 3	540
	11th to 20th	Night	10% 3 23% 42% 21% 1	540
	21st to end	Night	10% 3 26% 40% 20% 1	540
July	1st to 10th	Night	8% 1 11% 41% 34% 4	525
	11th to 20th	Night	5% 2 18% 45% 28% 2	522
	21st to end	Night	8% 3 10% 47% 31% 1	591
August	1st to 10th	Night	8% 2 11% 45% 31% 4	537
	11th to 20th	Night	8% 3 11% 39% 34% 5%	534
	21st to end	Night	8% 1 13% 41% 35% 2	594
September	1st to 10th	Night	14% 2 16% 38% 25% 3	540
	11th to 20th	Night	12% 2 18% 35% 28% 5%	540
	21st to end	Night	8% 5% 25% 34% 24% 3	688
October	1st to 10th	Night	13% 5% 27% 32% 20% 2	720
	11th to 20th	Night	17% 9% 33% 31% 11%	720
	21st to end	Night	21% 10% 35% 27% 6%	792
November	1st to 10th	Night	13% 10% 39% 29% 8% 1	740
	11th to 20th	Night	17% 12% 38% 25% 6% 1	783
	21st to end	Night	21% 10% 36% 25% 7%	950
December	1st to 10th	Night	19% 11% 38% 27% 4 1	950
	11th to 20th	Night	23% 8% 33% 28% 7%	950
	21st to end	Night	27% 14% 31% 24% 3	1045

Page generated at 2024-02-22 05:05:42. Version ac07

Copyright 2024 Attilla Danko