Bethune Beach
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bethune Beach clear sky chart from 2005-11-06 to 2024-11-12.

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	8% 5% 2 7% 5% 5% 6% 5% 8% 10% 38%	100950
	Night	8% 6% 2 7% 5% 5% 5% 5% 7% 9% 41%	98180
Transparency	Day	34% 10% 20% 21% 12% 3	104663
	Night	37% 9% 17% 20% 13% 4	102606
Seeing	Day	8% 4 16% 27% 29% 16%	15712
	Night	9% 4 15% 28% 31% 12%	25788

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% 7% 2 6% 5% 4 5% 4 5% 6% 43%	2836
	11th to 20th	Day	18% 10% 3 7% 5% 4 5% 4 5% 7% 33%	2840
	21st to end	Day	12% 7% 3 7% 5% 5% 6% 4 5% 7% 40%	3124
February	1st to 10th	Day	11% 6% 3 6% 5% 5% 5% 5% 6% 8% 40%	1871
	11th to 20th	Day	8% 5% 2 5% 4 4 4 3 6% 7% 51%	1851
	21st to end	Day	9% 6% 2 6% 4 5% 4 3 6% 7% 48%	1727
March	1st to 10th	Day	6% 8% 3 9% 6% 5% 6% 5% 7% 10% 35%	3435
	11th to 20th	Day	5% 3 2 5% 4 4 4 4 7% 10% 52%	3480
	21st to end	Day	10% 6% 2 6% 4 4 5% 5% 6% 7% 45%	3815
April	1st to 10th	Day	7% 4 2 5% 4 4 6% 4 6% 9% 50%	2090
	11th to 20th	Day	8% 5% 2 6% 5% 5% 5% 5% 7% 9% 41%	2165
	21st to end	Day	4 4 1 4 5% 4 6% 4 6% 9% 51%	2280
May	1st to 10th	Day	4 2 1 3 3 3 4 4 7% 11% 59%	3881
	11th to 20th	Day	8% 6% 2 7% 6% 6% 6% 6% 8% 10% 37%	4081
	21st to end	Day	4 3 1 5% 5% 4 5% 5% 8% 10% 51%	4476
June	1st to 10th	Day	10% 6% 2 8% 7% 7% 6% 6% 9% 12% 28%	2470
	11th to 20th	Day	6% 5% 2 8% 6% 7% 8% 7% 9% 12% 31%	2470
	21st to end	Day	8% 7% 2 8% 7% 6% 7% 6% 9% 10% 30%	2470
July	1st to 10th	Day	5% 4 2 7% 6% 6% 8% 6% 11% 12% 33%	4120
	11th to 20th	Day	5% 4 1 6% 6% 5% 8% 7% 10% 15% 32%	4120
	21st to end	Day	4 4 2 6% 7% 6% 8% 7% 11% 15% 30%	4466
August	1st to 10th	Day	5% 5% 2 8% 7% 7% 7% 6% 10% 13% 30%	4104
	11th to 20th	Day	3 3 2 6% 6% 6% 8% 6% 10% 13% 36%	3863
	21st to end	Day	7% 5% 3 7% 5% 6% 6% 6% 9% 14% 30%	3939
September	1st to 10th	Day	7% 7% 3 8% 8% 9% 9% 7% 9% 10% 24%	2090
	11th to 20th	Day	9% 6% 3 8% 7% 6% 8% 5% 10% 13% 25%	2090
	21st to end	Day	10% 7% 3 9% 6% 6% 6% 6% 8% 11% 28%	2090
October	1st to 10th	Day	13% 7% 3 8% 6% 6% 5% 6% 6% 10% 32%	2009
	11th to 20th	Day	7% 5% 3 6% 5% 6% 5% 5% 7% 9% 42%	1900
	21st to end	Day	8% 5% 1 5% 4 5% 5% 4 6% 10% 45%	2090
November	1st to 10th	Day	7% 7% 2 7% 6% 5% 6% 5% 8% 9% 39%	1957
	11th to 20th	Day	9% 7% 3 8% 6% 5% 5% 5% 6% 9% 38%	1910
	21st to end	Day	10% 8% 3 6% 7% 5% 5% 4 7% 7% 39%	1853
December	1st to 10th	Day	8% 5% 2 6% 5% 4 5% 4 7% 9% 46%	1710
	11th to 20th	Day	12% 7% 3 7% 5% 5% 5% 4 7% 7% 38%	2153
	21st to end	Day	11% 7% 3 9% 6% 6% 6% 5% 6% 7% 34%	3124
January	1st to 10th	Night	12% 7% 3 7% 5% 5% 4 4 6% 7% 39%	4109
	11th to 20th	Night	17% 11% 3 7% 5% 4 5% 4 6% 7% 32%	4120
	21st to end	Night	11% 7% 2 8% 5% 4 5% 4 6% 7% 40%	4532
February	1st to 10th	Night	11% 7% 2 6% 5% 4 4 4 6% 8% 43%	2304
	11th to 20th	Night	10% 6% 1 5% 5% 3 5% 4 5% 7% 49%	2214
	21st to end	Night	7% 5% 1 5% 5% 3 5% 4 6% 7% 52%	1727
March	1st to 10th	Night	12% 8% 3 9% 5% 4 4 3 5% 7% 39%	3418
	11th to 20th	Night	5% 3 2 4 4 4 5% 5% 8% 12% 51%	3480
	21st to end	Night	9% 7% 2 8% 4 4 5% 4 6% 6% 44%	3817
April	1st to 10th	Night	6% 4 2 5% 4 4 5% 4 7% 8% 52%	2090
	11th to 20th	Night	6% 6% 2 6% 5% 4 4 4 7% 7% 47%	1961
	21st to end	Night	5% 4 1 5% 5% 4 5% 4 5% 8% 53%	1900
May	1st to 10th	Night	3 2 1 2 2 3 4 4 6% 10% 62%	3041
	11th to 20th	Night	7% 6% 2 6% 4 5% 6% 5% 9% 10% 41%	2812
	21st to end	Night	4 4 2 5% 4 4 4 4 7% 11% 51%	3079
June	1st to 10th	Night	9% 6% 3 8% 5% 5% 6% 5% 8% 11% 34%	1710
	11th to 20th	Night	4 6% 3 7% 6% 7% 7% 5% 7% 11% 35%	1710
	21st to end	Night	6% 8% 3 8% 6% 5% 4 5% 9% 12% 35%	1710
July	1st to 10th	Night	5% 5% 2 6% 5% 6% 6% 5% 8% 13% 40%	2840
	11th to 20th	Night	4 5% 2 7% 6% 5% 6% 6% 10% 15% 33%	2840
	21st to end	Night	4 5% 2 8% 6% 7% 8% 6% 9% 13% 32%	3087
August	1st to 10th	Night	4 5% 3 9% 7% 6% 5% 5% 8% 11% 35%	2825
	11th to 20th	Night	3 3 2 6% 5% 6% 6% 5% 9% 13% 41%	2931
	21st to end	Night	7% 6% 3 7% 6% 6% 6% 5% 9% 14% 32%	3697
September	1st to 10th	Night	7% 7% 3 9% 7% 6% 8% 7% 9% 10% 27%	2090
	11th to 20th	Night	8% 8% 3 9% 7% 7% 6% 6% 8% 11% 26%	2090
	21st to end	Night	11% 6% 2 8% 6% 5% 7% 5% 8% 9% 32%	2090
October	1st to 10th	Night	10% 8% 4 9% 6% 5% 5% 5% 8% 9% 33%	2168
	11th to 20th	Night	6% 5% 2 6% 4 4 6% 4 6% 9% 49%	2280
	21st to end	Night	9% 5% 2 6% 4 4 5% 4 6% 9% 46%	2508
November	1st to 10th	Night	9% 6% 2 7% 5% 5% 6% 5% 6% 8% 40%	2341
	11th to 20th	Night	8% 7% 3 8% 5% 6% 5% 4 5% 8% 41%	2293
	21st to end	Night	10% 6% 3 8% 6% 5% 5% 4 7% 9% 37%	2322
December	1st to 10th	Night	7% 4 2 5% 6% 4 5% 4 7% 9% 46%	2470
	11th to 20th	Night	13% 9% 2 6% 4 4 4 3 6% 7% 42%	3042
	21st to end	Night	12% 9% 3 9% 5% 5% 5% 4 6% 7% 34%	4532

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	41% 5% 9% 16% 23% 6%	2837
	11th to 20th	Day	51% 5% 7% 16% 18% 3	2840
	21st to end	Day	41% 7% 10% 19% 16% 7%	3124
February	1st to 10th	Day	39% 6% 12% 18% 20% 5%	1871
	11th to 20th	Day	31% 5% 11% 23% 22% 8%	1861
	21st to end	Day	33% 6% 11% 19% 24% 7%	1727
March	1st to 10th	Day	40% 10% 16% 19% 13% 3	3435
	11th to 20th	Day	25% 7% 17% 31% 17% 3	3480
	21st to end	Day	34% 6% 14% 26% 13% 7%	3815
April	1st to 10th	Day	28% 8% 14% 25% 19% 7%	2090
	11th to 20th	Day	33% 10% 13% 22% 18% 4	2165
	21st to end	Day	24% 7% 15% 25% 23% 6%	2280
May	1st to 10th	Day	15% 8% 21% 36% 16% 4	3916
	11th to 20th	Day	37% 11% 19% 24% 9% 1	4085
	21st to end	Day	21% 9% 17% 39% 14% 1	4489
June	1st to 10th	Day	41% 12% 21% 21% 5%	2470
	11th to 20th	Day	36% 13% 23% 25% 2	2470
	21st to end	Day	38% 14% 28% 15% 4	2470
July	1st to 10th	Day	31% 14% 34% 18% 3	4055
	11th to 20th	Day	28% 16% 45% 11% 1	4051
	21st to end	Day	28% 19% 39% 14% 1	4324
August	1st to 10th	Day	35% 16% 36% 12% 1	4091
	11th to 20th	Day	26% 15% 32% 20% 7%	3902
	21st to end	Day	35% 16% 32% 15% 2	3939
September	1st to 10th	Day	41% 19% 23% 11% 5%	2090
	11th to 20th	Day	41% 16% 26% 14% 4	2090
	21st to end	Day	41% 13% 18% 16% 10% 2	2090
October	1st to 10th	Day	51% 10% 15% 12% 9% 3	3334
	11th to 20th	Day	30% 7% 7% 24% 26% 6%	3140
	21st to end	Day	27% 6% 8% 25% 29% 5%	3428
November	1st to 10th	Day	35% 8% 12% 20% 18% 6%	1957
	11th to 20th	Day	43% 7% 9% 19% 17% 5%	1910
	21st to end	Day	41% 6% 10% 22% 18% 3	1853
December	1st to 10th	Day	34% 8% 15% 27% 13% 4	1710
	11th to 20th	Day	43% 6% 11% 16% 18% 6%	2150
	21st to end	Day	44% 7% 10% 18% 14% 6%	3124
January	1st to 10th	Night	43% 5% 9% 18% 19% 6%	4109
	11th to 20th	Night	50% 6% 9% 18% 13% 4	4120
	21st to end	Night	40% 8% 11% 17% 16% 8%	4532
February	1st to 10th	Night	37% 6% 12% 18% 17% 10%	2304
	11th to 20th	Night	34% 7% 12% 21% 18% 9%	2215
	21st to end	Night	31% 6% 14% 19% 23% 7%	1727
March	1st to 10th	Night	43% 8% 14% 19% 13% 4	3418
	11th to 20th	Night	23% 8% 21% 30% 13% 4	3480
	21st to end	Night	37% 8% 11% 19% 20% 6%	3817
April	1st to 10th	Night	27% 8% 17% 23% 15% 9%	2090
	11th to 20th	Night	34% 8% 11% 25% 18% 5%	1961
	21st to end	Night	28% 7% 14% 26% 20% 5%	1900
May	1st to 10th	Night	14% 9% 23% 34% 16% 4	3071
	11th to 20th	Night	31% 11% 22% 26% 9% 1	2813
	21st to end	Night	23% 10% 17% 34% 16% 1	3087
June	1st to 10th	Night	40% 11% 22% 22% 5%	1710
	11th to 20th	Night	37% 12% 24% 24% 3	1710
	21st to end	Night	39% 12% 25% 18% 5% 1	1710
July	1st to 10th	Night	33% 14% 33% 18% 2	2795
	11th to 20th	Night	31% 15% 44% 8% 1	2786
	21st to end	Night	35% 16% 33% 15% 1	2988
August	1st to 10th	Night	38% 13% 37% 11% 1	2814
	11th to 20th	Night	28% 13% 31% 22% 6%	2958
	21st to end	Night	39% 14% 30% 15% 2	3697
September	1st to 10th	Night	45% 18% 20% 12% 5%	2090
	11th to 20th	Night	47% 13% 22% 14% 3	2090
	21st to end	Night	44% 12% 14% 18% 10% 2	2090
October	1st to 10th	Night	57% 8% 11% 13% 8% 3	3623
	11th to 20th	Night	31% 7% 7% 25% 26% 4	3779
	21st to end	Night	30% 5% 8% 22% 30% 5%	4120
November	1st to 10th	Night	39% 9% 11% 19% 18% 5%	2341
	11th to 20th	Night	42% 7% 10% 19% 15% 6%	2293
	21st to end	Night	42% 7% 12% 20% 16% 3	2322
December	1st to 10th	Night	32% 7% 16% 30% 11% 4	2470
	11th to 20th	Night	43% 5% 10% 19% 17% 6%	3044
	21st to end	Night	47% 8% 10% 18% 14% 4	4532

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	16% 4 37% 30% 11% 3	270
	11th to 20th	Day	7% 6% 36% 31% 15% 5%	270
	21st to end	Day	16% 10% 33% 31% 8% 1	297
February	1st to 10th	Day	12% 7% 31% 32% 17% 1	270
	11th to 20th	Day	8% 5% 29% 39% 16% 3	273
	21st to end	Day	7% 5% 29% 36% 20% 3	382
March	1st to 10th	Day	5% 8% 35% 37% 15% 1	460
	11th to 20th	Day	8% 6% 27% 34% 20% 4	460
	21st to end	Day	7% 5% 30% 34% 21% 3	506
April	1st to 10th	Day	7% 6% 33% 36% 16% 3	460
	11th to 20th	Day	8% 6% 26% 33% 24% 3	452
	21st to end	Day	6% 2 20% 42% 23% 7%	460
May	1st to 10th	Day	5% 3 19% 41% 26% 7%	463
	11th to 20th	Day	10% 2 13% 33% 32% 10%	487
	21st to end	Day	7% 2 7% 29% 37% 19%	529
June	1st to 10th	Day	11% 2 7% 29% 35% 17%	490
	11th to 20th	Day	4 3 6% 22% 39% 27%	490
	21st to end	Day	7% 3 1 12% 43% 33%	490
July	1st to 10th	Day	6% 2 2 8% 37% 44%	485
	11th to 20th	Day	5% 2 1 8% 42% 42%	484
	21st to end	Day	6% 2 2 14% 39% 38%	532
August	1st to 10th	Day	6% 3 3 13% 43% 33%	486
	11th to 20th	Day	3 1 1 9% 38% 48%	479
	21st to end	Day	9% 3 4 9% 38% 36%	539
September	1st to 10th	Day	11% 3 3 12% 37% 34%	490
	11th to 20th	Day	10% 4 4 19% 40% 23%	490
	21st to end	Day	9% 3 4 22% 38% 24%	490
October	1st to 10th	Day	17% 4 11% 34% 26% 8%	490
	11th to 20th	Day	7% 4 12% 36% 31% 9%	490
	21st to end	Day	7% 3 18% 35% 30% 6%	539
November	1st to 10th	Day	7% 7% 17% 34% 27% 7%	495
	11th to 20th	Day	14% 5% 22% 36% 18% 4	464
	21st to end	Day	12% 5% 22% 37% 21% 3	413
December	1st to 10th	Day	5% 4 27% 39% 18% 6%	270
	11th to 20th	Day	10% 4 31% 33% 19% 3	270
	21st to end	Day	7% 4 27% 35% 24% 3	297
January	1st to 10th	Night	13% 10% 24% 35% 16% 2	760
	11th to 20th	Night	10% 8% 27% 34% 19% 3	760
	21st to end	Night	13% 11% 31% 34% 11%	836
February	1st to 10th	Night	13% 7% 25% 35% 18% 2	760
	11th to 20th	Night	12% 7% 26% 37% 16% 2	743
	21st to end	Night	8% 5% 30% 40% 17% 1	628
March	1st to 10th	Night	6% 6% 30% 38% 19% 1	760
	11th to 20th	Night	9% 4 22% 40% 21% 4	760
	21st to end	Night	8% 5% 25% 36% 24% 2	836
April	1st to 10th	Night	8% 4 25% 39% 21% 3	760
	11th to 20th	Night	8% 5% 23% 36% 26% 2	751
	21st to end	Night	6% 3 19% 40% 28% 3	760
May	1st to 10th	Night	7% 1 14% 43% 33% 3	710
	11th to 20th	Night	8% 3 12% 31% 35% 11%	561
	21st to end	Night	7% 2 6% 24% 45% 16%	617
June	1st to 10th	Night	11% 2 6% 24% 43% 13%	570
	11th to 20th	Night	6% 2 4 19% 43% 26%	570
	21st to end	Night	8% 2 2 14% 45% 29%	570
July	1st to 10th	Night	8% 2 1 11% 45% 32%	555
	11th to 20th	Night	5% 2 1 8% 44% 39%	552
	21st to end	Night	5% 2 1 10% 47% 35%	624
August	1st to 10th	Night	5% 2 2 10% 48% 33%	567
	11th to 20th	Night	4 2 1 8% 46% 40%	645
	21st to end	Night	11% 3 4 11% 42% 29%	836
September	1st to 10th	Night	9% 2 3 11% 46% 29%	760
	11th to 20th	Night	11% 3 3 20% 43% 19%	760
	21st to end	Night	14% 3 4 18% 42% 20%	760
October	1st to 10th	Night	14% 4 11% 30% 32% 9%	760
	11th to 20th	Night	8% 5% 10% 31% 38% 9%	760
	21st to end	Night	10% 3 14% 33% 34% 7%	836
November	1st to 10th	Night	12% 3 18% 31% 29% 7%	780
	11th to 20th	Night	10% 7% 19% 36% 24% 4	765
	21st to end	Night	11% 6% 21% 38% 22% 3	760
December	1st to 10th	Night	9% 6% 23% 31% 27% 6%	760
	11th to 20th	Night	14% 6% 20% 32% 24% 4	760
	21st to end	Night	12% 6% 23% 33% 25% 3	836

Page generated at 2024-11-08 22:45:34. Version ac07

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