South Baymouth
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the South Baymouth clear sky chart from 2005-11-06 to 2024-03-01.

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	15% 10% 4 7% 6% 3 5% 5% 5% 7% 34%	78154
	Night	15% 12% 5% 8% 6% 4 5% 4 5% 6% 29%	81280
Transparency	Day	49% 7% 13% 19% 10% 1	77856
	Night	56% 7% 12% 16% 8% 1	81114
Seeing	Day	18% 12% 31% 26% 11% 2	14298
	Night	21% 13% 29% 24% 11% 2	23787

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	19% 19% 11% 11% 6% 3 4 2 3 5% 17%	2239
	11th to 20th	Day	11% 15% 8% 16% 15% 5% 6% 4 5% 5% 12%	2530
	21st to end	Day	17% 19% 8% 11% 9% 4 5% 5% 5% 5% 14%	2967
February	1st to 10th	Day	11% 15% 7% 12% 9% 5% 5% 5% 4 5% 22%	1710
	11th to 20th	Day	12% 13% 6% 11% 6% 4 4 5% 5% 6% 28%	1663
	21st to end	Day	13% 14% 5% 12% 6% 4 4 5% 6% 6% 26%	1559
March	1st to 10th	Day	13% 9% 4 6% 5% 3 5% 4 6% 7% 38%	1873
	11th to 20th	Day	12% 9% 5% 8% 6% 4 5% 4 5% 6% 36%	1980
	21st to end	Day	15% 8% 3 6% 5% 3 5% 5% 5% 6% 39%	2178
April	1st to 10th	Day	18% 10% 3 5% 6% 3 5% 4 6% 7% 32%	2111
	11th to 20th	Day	18% 8% 2 6% 5% 3 4 5% 5% 6% 38%	2312
	21st to end	Day	19% 8% 3 6% 5% 3 4 4 5% 8% 37%	2340
May	1st to 10th	Day	17% 7% 2 5% 5% 3 4 4 5% 8% 40%	2340
	11th to 20th	Day	16% 6% 3 5% 5% 2 4 4 5% 7% 42%	2382
	21st to end	Day	12% 4 2 5% 6% 4 4 4 6% 8% 44%	2808
June	1st to 10th	Day	13% 5% 2 6% 6% 4 5% 6% 6% 8% 40%	2700
	11th to 20th	Day	11% 5% 3 5% 5% 3 5% 6% 6% 9% 42%	2700
	21st to end	Day	13% 6% 3 5% 5% 3 5% 5% 7% 8% 40%	2700
July	1st to 10th	Day	8% 5% 2 5% 5% 4 4 5% 6% 8% 49%	2700
	11th to 20th	Day	9% 5% 2 6% 5% 3 5% 5% 7% 9% 43%	2646
	21st to end	Day	10% 4 2 4 4 3 4 4 6% 10% 48%	2653
August	1st to 10th	Day	10% 5% 2 4 5% 3 5% 4 7% 9% 46%	2327
	11th to 20th	Day	9% 4 2 4 6% 3 4 5% 6% 8% 48%	2303
	21st to end	Day	10% 5% 2 5% 6% 3 5% 6% 7% 8% 42%	2574
September	1st to 10th	Day	11% 5% 3 6% 6% 3 4 5% 6% 8% 43%	2127
	11th to 20th	Day	13% 4 2 4 5% 3 5% 4 6% 8% 47%	1980
	21st to end	Day	16% 6% 3 6% 7% 3 3 5% 6% 8% 37%	1980
October	1st to 10th	Day	17% 8% 3 6% 6% 4 4 5% 6% 7% 35%	1854
	11th to 20th	Day	25% 10% 3 7% 7% 3 4 4 4 6% 26%	1800
	21st to end	Day	25% 11% 4 7% 8% 4 5% 5% 4 6% 22%	1844
November	1st to 10th	Day	18% 13% 4 8% 6% 3 5% 6% 5% 8% 26%	1650
	11th to 20th	Day	18% 15% 5% 10% 6% 3 6% 4 6% 7% 20%	1520
	21st to end	Day	24% 20% 6% 8% 6% 4 3 5% 4 6% 13%	1520
December	1st to 10th	Day	15% 21% 10% 11% 7% 4 5% 4 4 5% 14%	1482
	11th to 20th	Day	21% 18% 7% 11% 6% 4 6% 3 4 4 16%	1671
	21st to end	Day	27% 23% 5% 10% 7% 4 4 3 5% 3 8%	2431
January	1st to 10th	Night	16% 19% 10% 12% 7% 3 4 3 4 5% 16%	4716
	11th to 20th	Night	12% 15% 7% 18% 10% 4 5% 5% 5% 5% 14%	4440
	21st to end	Night	15% 19% 7% 12% 9% 4 4 4 3 5% 18%	4692
February	1st to 10th	Night	11% 16% 7% 12% 8% 4 5% 5% 5% 5% 22%	2470
	11th to 20th	Night	10% 14% 6% 10% 8% 4 6% 5% 5% 5% 27%	2403
	21st to end	Night	15% 16% 5% 9% 7% 3 4 5% 6% 6% 25%	1893
March	1st to 10th	Night	11% 9% 5% 7% 6% 4 4 4 5% 6% 39%	2081
	11th to 20th	Night	12% 11% 4 7% 7% 4 4 4 5% 6% 37%	1979
	21st to end	Night	14% 8% 3 6% 5% 3 5% 4 5% 8% 39%	2178
April	1st to 10th	Night	20% 8% 3 6% 5% 3 4 5% 5% 6% 35%	1865
	11th to 20th	Night	18% 7% 3 5% 3 3 4 5% 5% 8% 38%	1597
	21st to end	Night	18% 10% 4 7% 6% 3 5% 4 5% 6% 33%	1620
May	1st to 10th	Night	13% 7% 3 7% 7% 5% 6% 5% 5% 6% 36%	1620
	11th to 20th	Night	14% 6% 3 7% 6% 3 6% 5% 5% 6% 39%	1509
	21st to end	Night	11% 6% 3 5% 5% 4 4 5% 5% 8% 44%	1464
June	1st to 10th	Night	11% 7% 3 5% 5% 3 5% 6% 7% 7% 40%	1260
	11th to 20th	Night	10% 6% 2 4 4 3 5% 6% 7% 9% 44%	1260
	21st to end	Night	12% 6% 2 6% 6% 3 5% 5% 5% 8% 41%	1260
July	1st to 10th	Night	8% 3 2 3 5% 3 4 5% 5% 9% 53%	1260
	11th to 20th	Night	7% 4 3 5% 5% 3 6% 6% 6% 8% 47%	1311
	21st to end	Night	8% 4 2 6% 6% 3 4 5% 5% 6% 50%	1662
August	1st to 10th	Night	8% 4 2 5% 4 3 5% 6% 6% 8% 50%	1611
	11th to 20th	Night	9% 4 2 5% 5% 4 5% 5% 7% 8% 47%	1598
	21st to end	Night	11% 6% 3 5% 5% 3 5% 4 5% 8% 46%	1782
September	1st to 10th	Night	13% 4 2 5% 4 3 4 4 5% 8% 47%	1812
	11th to 20th	Night	11% 5% 2 5% 5% 4 4 4 6% 7% 48%	1980
	21st to end	Night	17% 6% 2 6% 5% 3 5% 4 5% 8% 38%	1980
October	1st to 10th	Night	19% 8% 4 6% 6% 3 4 5% 5% 6% 35%	2106
	11th to 20th	Night	24% 9% 3 7% 7% 4 5% 4 5% 6% 25%	2160
	21st to end	Night	25% 11% 4 7% 7% 3 4 5% 5% 5% 23%	2510
November	1st to 10th	Night	19% 13% 4 6% 5% 3 5% 5% 5% 7% 28%	2426
	11th to 20th	Night	18% 17% 5% 9% 7% 4 6% 4 4 6% 19%	2660
	21st to end	Night	22% 18% 6% 8% 8% 4 5% 4 5% 5% 16%	2660
December	1st to 10th	Night	20% 21% 9% 10% 7% 4 4 3 4 4 14%	2693
	11th to 20th	Night	19% 19% 6% 10% 7% 4 5% 4 5% 5% 17%	3526
	21st to end	Night	25% 21% 7% 12% 6% 4 4 3 4 4 12%	5236

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	72% 9% 11% 7% 1	2240
	11th to 20th	Day	78% 8% 7% 5% 2	2530
	21st to end	Day	72% 10% 10% 7% 2	2967
February	1st to 10th	Day	65% 7% 12% 13% 3	1710
	11th to 20th	Day	57% 8% 14% 14% 6% 1	1672
	21st to end	Day	56% 8% 14% 18% 4	1559
March	1st to 10th	Day	45% 7% 16% 18% 12% 2	1876
	11th to 20th	Day	49% 6% 12% 22% 9% 3	1980
	21st to end	Day	45% 6% 13% 19% 14% 3	2178
April	1st to 10th	Day	49% 7% 14% 18% 11% 1	2111
	11th to 20th	Day	45% 5% 10% 25% 13% 2	2312
	21st to end	Day	46% 5% 13% 19% 13% 3	2340
May	1st to 10th	Day	42% 6% 10% 24% 14% 3	2340
	11th to 20th	Day	40% 6% 11% 23% 18% 1	2386
	21st to end	Day	38% 6% 16% 22% 16% 2	2808
June	1st to 10th	Day	39% 7% 13% 25% 14% 2	2700
	11th to 20th	Day	36% 7% 13% 26% 17% 2	2700
	21st to end	Day	40% 8% 13% 24% 13% 2	2700
July	1st to 10th	Day	29% 7% 16% 28% 18% 2	2626
	11th to 20th	Day	33% 9% 15% 28% 12% 1	2565
	21st to end	Day	31% 8% 16% 29% 16% 1	2506
August	1st to 10th	Day	32% 8% 19% 27% 13% 1	2314
	11th to 20th	Day	31% 9% 19% 30% 11%	2303
	21st to end	Day	35% 10% 17% 25% 11% 1	2574
September	1st to 10th	Day	37% 8% 16% 28% 10% 1	2127
	11th to 20th	Day	34% 8% 18% 31% 9% 1	1980
	21st to end	Day	44% 10% 16% 23% 8%	1980
October	1st to 10th	Day	49% 8% 12% 19% 12%	1854
	11th to 20th	Day	59% 7% 14% 15% 5%	1800
	21st to end	Day	63% 7% 12% 12% 5%	1844
November	1st to 10th	Day	56% 8% 14% 17% 5%	1650
	11th to 20th	Day	64% 8% 14% 10% 5%	1520
	21st to end	Day	72% 6% 12% 8% 2	1520
December	1st to 10th	Day	74% 8% 10% 6% 2	1482
	11th to 20th	Day	74% 6% 9% 10% 1	1671
	21st to end	Day	80% 9% 6% 5%	2431
January	1st to 10th	Night	70% 10% 10% 8% 2	4716
	11th to 20th	Night	74% 9% 9% 6% 2	4440
	21st to end	Night	71% 7% 11% 9% 2	4692
February	1st to 10th	Night	65% 5% 10% 14% 4	2470
	11th to 20th	Night	58% 8% 13% 15% 5% 1	2405
	21st to end	Night	58% 8% 13% 14% 7% 1	1893
March	1st to 10th	Night	46% 6% 14% 21% 11% 1	2091
	11th to 20th	Night	49% 5% 11% 21% 12% 2	1980
	21st to end	Night	45% 6% 12% 19% 15% 4	2178
April	1st to 10th	Night	49% 5% 10% 20% 14% 2	1865
	11th to 20th	Night	42% 6% 9% 23% 18% 2	1597
	21st to end	Night	50% 6% 9% 17% 15% 3	1620
May	1st to 10th	Night	46% 6% 11% 20% 14% 3	1620
	11th to 20th	Night	44% 5% 9% 22% 17% 3	1510
	21st to end	Night	37% 8% 14% 21% 15% 4	1465
June	1st to 10th	Night	39% 7% 10% 23% 18% 3	1260
	11th to 20th	Night	34% 8% 13% 23% 19% 2	1260
	21st to end	Night	40% 7% 14% 23% 13% 2	1260
July	1st to 10th	Night	27% 6% 13% 29% 21% 4	1225
	11th to 20th	Night	31% 9% 13% 29% 17% 1	1269
	21st to end	Night	34% 7% 15% 26% 17% 1	1570
August	1st to 10th	Night	30% 9% 19% 29% 12% 2	1600
	11th to 20th	Night	32% 9% 17% 28% 13% 1	1598
	21st to end	Night	36% 7% 18% 25% 12% 2	1782
September	1st to 10th	Night	35% 7% 14% 27% 14% 2	1812
	11th to 20th	Night	35% 7% 16% 32% 9%	1980
	21st to end	Night	43% 8% 16% 24% 8%	1980
October	1st to 10th	Night	51% 6% 11% 20% 11%	2106
	11th to 20th	Night	60% 7% 12% 17% 4	2160
	21st to end	Night	63% 7% 11% 13% 5%	2510
November	1st to 10th	Night	55% 7% 12% 19% 6%	2426
	11th to 20th	Night	67% 7% 12% 10% 4	2660
	21st to end	Night	70% 7% 12% 9% 2	2660
December	1st to 10th	Night	75% 7% 9% 8% 1	2693
	11th to 20th	Night	70% 7% 11% 9% 3	3525
	21st to end	Night	77% 9% 8% 5% 1	5236

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% 21% 32% 16% 4	189
	11th to 20th	Day	21% 17% 37% 20% 5%	270
	21st to end	Day	28% 13% 32% 19% 8%	297
February	1st to 10th	Day	22% 25% 34% 13% 5%	270
	11th to 20th	Day	19% 23% 38% 17% 2	270
	21st to end	Day	26% 27% 38% 8% 1	225
March	1st to 10th	Day	22% 18% 35% 19% 5% 1	316
	11th to 20th	Day	19% 15% 37% 23% 5% 1	420
	21st to end	Day	23% 15% 33% 23% 6% 1	462
April	1st to 10th	Day	22% 15% 31% 24% 8% 1	420
	11th to 20th	Day	25% 17% 27% 18% 10% 3	412
	21st to end	Day	25% 13% 35% 19% 8% 1	420
May	1st to 10th	Day	21% 9% 36% 24% 9% 2	423
	11th to 20th	Day	17% 11% 29% 28% 13% 2	447
	21st to end	Day	13% 7% 33% 30% 14% 3	568
June	1st to 10th	Day	13% 8% 33% 31% 13% 1	630
	11th to 20th	Day	13% 8% 31% 33% 13% 2	630
	21st to end	Day	15% 8% 30% 33% 12% 3	630
July	1st to 10th	Day	8% 5% 29% 39% 18% 2	621
	11th to 20th	Day	11% 6% 28% 37% 13% 4	618
	21st to end	Day	11% 4 32% 36% 14% 4	594
August	1st to 10th	Day	13% 6% 23% 34% 19% 5%	446
	11th to 20th	Day	11% 5% 22% 35% 20% 8%	439
	21st to end	Day	13% 8% 28% 30% 17% 4	495
September	1st to 10th	Day	13% 9% 27% 27% 18% 5%	450
	11th to 20th	Day	14% 7% 25% 33% 16% 4	450
	21st to end	Day	19% 12% 25% 26% 15% 4	450
October	1st to 10th	Day	20% 18% 24% 25% 12% 2	450
	11th to 20th	Day	25% 20% 34% 16% 5% 1	450
	21st to end	Day	28% 23% 32% 13% 3 1	359
November	1st to 10th	Day	28% 18% 34% 15% 5%	259
	11th to 20th	Day	26% 22% 34% 14% 3	180
	21st to end	Day	33% 23% 31% 11% 2	180
December	1st to 10th	Day	27% 24% 29% 15% 5%	180
	11th to 20th	Day	32% 23% 35% 9% 2	180
	21st to end	Day	31% 28% 33% 5% 3 1	198
January	1st to 10th	Night	23% 22% 30% 20% 4	950
	11th to 20th	Night	25% 19% 31% 20% 5% 1	950
	21st to end	Night	22% 12% 35% 22% 8% 1	931
February	1st to 10th	Night	19% 21% 35% 20% 4	760
	11th to 20th	Night	18% 17% 34% 24% 6%	743
	21st to end	Night	21% 17% 36% 20% 4	628
March	1st to 10th	Night	18% 16% 36% 23% 7% 1	723
	11th to 20th	Night	18% 15% 36% 22% 8% 1	720
	21st to end	Night	19% 11% 32% 30% 9% 1	792
April	1st to 10th	Night	24% 11% 33% 26% 5% 1	665
	11th to 20th	Night	22% 11% 30% 24% 11% 2	533
	21st to end	Night	22% 9% 29% 26% 13% 1	540
May	1st to 10th	Night	15% 6% 28% 34% 14% 3	540
	11th to 20th	Night	17% 7% 26% 32% 17% 1	448
	21st to end	Night	14% 4 27% 34% 19% 2	389
June	1st to 10th	Night	15% 3 32% 34% 14% 2	360
	11th to 20th	Night	11% 8% 22% 38% 19% 2	360
	21st to end	Night	14% 3 21% 37% 23% 2	360
July	1st to 10th	Night	10% 3 21% 41% 24% 1	350
	11th to 20th	Night	9% 3 20% 39% 25% 5%	399
	21st to end	Night	9% 3 24% 35% 26% 3	591
August	1st to 10th	Night	9% 4 21% 38% 24% 4	537
	11th to 20th	Night	11% 4 17% 31% 32% 5%	534
	21st to end	Night	13% 4 23% 32% 22% 6%	594
September	1st to 10th	Night	14% 6% 25% 27% 20% 7%	670
	11th to 20th	Night	13% 6% 26% 31% 15% 8%	720
	21st to end	Night	18% 9% 25% 25% 18% 5%	720
October	1st to 10th	Night	22% 11% 25% 27% 13% 2	720
	11th to 20th	Night	29% 15% 28% 18% 10%	720
	21st to end	Night	29% 17% 29% 20% 4 1	792
November	1st to 10th	Night	26% 15% 30% 21% 7% 1	740
	11th to 20th	Night	26% 23% 28% 17% 6%	760
	21st to end	Night	32% 18% 29% 16% 5%	760
December	1st to 10th	Night	31% 22% 29% 12% 5%	793
	11th to 20th	Night	28% 22% 32% 12% 4 1	950
	21st to end	Night	34% 17% 30% 14% 4	1045

Page generated at 2024-02-27 06:30:13. Version ac07

Copyright © 2024 Attilla Danko.