Bay Roberts
Clear Sky Chart
History

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

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	21% 16% 5% 10% 5% 5% 4 3 4 5% 21%	101683
	Night	22% 15% 6% 11% 6% 4 4 3 4 5% 19%	97621
Transparency	Day	63% 7% 11% 14% 5%	105183
	Night	64% 7% 11% 13% 5%	102236
Seeing	Day	27% 17% 29% 19% 7% 1	18173
	Night	28% 17% 31% 19% 5%	24740

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	18% 15% 8% 18% 5% 4 4 2 3 5% 18%	2216
	11th to 20th	Day	20% 19% 6% 16% 5% 4 4 3 2 4 17%	2497
	21st to end	Day	15% 17% 8% 17% 6% 5% 4 3 4 4 17%	2783
February	1st to 10th	Day	20% 16% 7% 12% 8% 7% 5% 3 5% 4 15%	1649
	11th to 20th	Day	20% 17% 6% 14% 7% 6% 4 4 4 4 13%	1674
	21st to end	Day	13% 19% 8% 15% 8% 6% 4 4 4 4 16%	1570
March	1st to 10th	Day	25% 16% 7% 13% 6% 5% 4 2 3 3 17%	3140
	11th to 20th	Day	22% 19% 10% 13% 7% 4 3 3 3 4 12%	3480
	21st to end	Day	24% 21% 8% 11% 6% 4 4 3 3 4 12%	3817
April	1st to 10th	Day	20% 21% 7% 11% 5% 4 4 2 5% 4 16%	2294
	11th to 20th	Day	24% 20% 5% 8% 5% 4 3 2 4 5% 21%	2441
	21st to end	Day	26% 19% 5% 8% 5% 4 3 2 4 5% 19%	2470
May	1st to 10th	Day	25% 24% 5% 7% 4 4 4 2 4 5% 15%	4105
	11th to 20th	Day	27% 19% 5% 9% 5% 4 3 3 4 5% 17%	4434
	21st to end	Day	21% 19% 5% 10% 4 5% 4 3 4 5% 19%	5173
June	1st to 10th	Day	31% 18% 4 8% 5% 4 3 2 3 5% 16%	2850
	11th to 20th	Day	25% 14% 3 7% 5% 4 5% 4 4 6% 23%	2850
	21st to end	Day	23% 14% 4 9% 6% 3 4 3 5% 6% 23%	2850
July	1st to 10th	Day	25% 14% 4 9% 5% 4 4 3 5% 6% 22%	4750
	11th to 20th	Day	16% 13% 4 11% 7% 6% 5% 4 5% 6% 24%	4722
	21st to end	Day	15% 10% 3 7% 4 4 4 3 5% 7% 36%	4815
August	1st to 10th	Day	20% 12% 6% 12% 5% 5% 4 3 5% 6% 22%	4187
	11th to 20th	Day	17% 11% 4 9% 6% 5% 5% 4 6% 7% 26%	4046
	21st to end	Day	18% 10% 3 8% 5% 4 5% 3 5% 7% 30%	4532
September	1st to 10th	Day	20% 11% 3 7% 5% 4 5% 4 5% 7% 30%	2272
	11th to 20th	Day	23% 9% 4 7% 5% 5% 4 3 4 6% 30%	2090
	21st to end	Day	18% 9% 3 8% 5% 5% 4 3 5% 8% 33%	2090
October	1st to 10th	Day	21% 13% 3 9% 4 4 4 4 5% 7% 27%	1995
	11th to 20th	Day	23% 15% 4 9% 6% 5% 5% 4 5% 4 22%	1855
	21st to end	Day	25% 16% 4 8% 6% 5% 5% 3 4 5% 18%	1881
November	1st to 10th	Day	21% 16% 4 10% 6% 4 4 3 5% 5% 23%	1732
	11th to 20th	Day	22% 17% 6% 10% 5% 5% 4 3 4 7% 18%	1520
	21st to end	Day	23% 21% 5% 9% 6% 5% 4 3 4 5% 17%	1463
December	1st to 10th	Day	22% 19% 6% 12% 6% 4 4 3 3 6% 15%	1330
	11th to 20th	Day	24% 19% 7% 11% 5% 5% 4 3 3 4 15%	1668
	21st to end	Day	19% 21% 8% 13% 6% 5% 4 3 5% 4 13%	2442
January	1st to 10th	Night	16% 19% 10% 13% 8% 5% 4 2 4 4 15%	4739
	11th to 20th	Night	17% 15% 6% 18% 7% 5% 4 3 4 5% 15%	4471
	21st to end	Night	13% 14% 9% 17% 8% 5% 5% 4 5% 4 16%	4884
February	1st to 10th	Night	19% 16% 6% 15% 8% 5% 4 3 4 4 14%	2530
	11th to 20th	Night	22% 15% 5% 12% 8% 5% 5% 3 5% 4 14%	2389
	21st to end	Night	14% 17% 6% 13% 6% 6% 5% 3 5% 5% 19%	1884
March	1st to 10th	Night	25% 13% 7% 13% 5% 4 3 3 4 4 20%	3700
	11th to 20th	Night	16% 16% 9% 16% 8% 5% 5% 3 4 5% 14%	3479
	21st to end	Night	29% 17% 7% 10% 5% 3 4 3 4 3 14%	3815
April	1st to 10th	Night	23% 22% 5% 10% 5% 4 3 2 4 4 19%	1881
	11th to 20th	Night	24% 15% 5% 10% 5% 3 4 2 4 4 23%	1688
	21st to end	Night	26% 20% 5% 8% 5% 3 3 2 3 4 20%	1710
May	1st to 10th	Night	29% 22% 8% 7% 4 3 3 3 3 5% 14%	2845
	11th to 20th	Night	30% 19% 5% 10% 4 3 3 3 4 4 15%	2466
	21st to end	Night	23% 18% 5% 10% 6% 5% 4 3 4 5% 16%	2412
June	1st to 10th	Night	28% 18% 4 8% 4 4 4 4 4 4 18%	1330
	11th to 20th	Night	25% 13% 4 8% 5% 4 4 5% 5% 7% 22%	1330
	21st to end	Night	23% 14% 4 9% 6% 5% 4 3 5% 5% 22%	1330
July	1st to 10th	Night	31% 12% 4 10% 5% 4 4 3 4 6% 18%	2220
	11th to 20th	Night	15% 14% 7% 16% 7% 7% 6% 4 4 5% 15%	2245
	21st to end	Night	14% 10% 3 10% 6% 5% 4 4 6% 6% 33%	2750
August	1st to 10th	Night	17% 11% 5% 13% 5% 5% 4 4 6% 7% 23%	2738
	11th to 20th	Night	25% 7% 3 8% 4 4 4 4 5% 7% 27%	2791
	21st to end	Night	24% 10% 3 8% 4 3 4 4 6% 7% 28%	3135
September	1st to 10th	Night	20% 11% 4 7% 4 5% 4 4 5% 7% 30%	1904
	11th to 20th	Night	23% 11% 3 9% 4 4 4 4 5% 6% 27%	2090
	21st to end	Night	20% 12% 3 9% 5% 4 4 3 4 6% 31%	2090
October	1st to 10th	Night	21% 12% 4 10% 5% 4 4 4 5% 7% 26%	2185
	11th to 20th	Night	24% 15% 3 7% 5% 5% 4 4 5% 7% 23%	2323
	21st to end	Night	24% 17% 4 9% 4 4 4 3 4 5% 22%	2717
November	1st to 10th	Night	22% 15% 5% 9% 6% 4 4 3 4 6% 22%	2564
	11th to 20th	Night	22% 17% 5% 10% 5% 5% 3 3 4 6% 20%	2667
	21st to end	Night	19% 17% 5% 11% 6% 4 5% 4 5% 5% 19%	2713
December	1st to 10th	Night	20% 20% 5% 12% 6% 5% 4 3 4 5% 17%	2850
	11th to 20th	Night	29% 17% 6% 13% 6% 4 3 3 3 4 12%	3531
	21st to end	Night	21% 17% 6% 12% 5% 4 5% 3 4 4 18%	5225

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	70% 5% 6% 12% 6% 2	2217
	11th to 20th	Day	69% 6% 10% 8% 6% 1	2497
	21st to end	Day	69% 5% 7% 10% 8%	2783
February	1st to 10th	Day	71% 8% 8% 7% 6% 1	1649
	11th to 20th	Day	71% 7% 9% 9% 4 1	1681
	21st to end	Day	69% 6% 9% 8% 6% 1	1570
March	1st to 10th	Day	70% 6% 8% 10% 5% 1	3145
	11th to 20th	Day	74% 6% 9% 8% 3	3480
	21st to end	Day	74% 6% 7% 10% 2 1	3817
April	1st to 10th	Day	70% 6% 7% 11% 5% 1	2294
	11th to 20th	Day	65% 6% 7% 12% 8% 1	2441
	21st to end	Day	67% 5% 8% 11% 8% 1	2470
May	1st to 10th	Day	70% 7% 9% 10% 4	4120
	11th to 20th	Day	68% 8% 9% 11% 4	4438
	21st to end	Day	64% 7% 9% 14% 5%	5173
June	1st to 10th	Day	72% 5% 7% 11% 4 1	2850
	11th to 20th	Day	59% 8% 13% 13% 6%	2850
	21st to end	Day	61% 8% 11% 15% 6%	2850
July	1st to 10th	Day	61% 7% 13% 14% 5%	4675
	11th to 20th	Day	55% 10% 16% 13% 6%	4640
	21st to end	Day	45% 7% 21% 22% 6%	4662
August	1st to 10th	Day	60% 7% 13% 17% 3	4173
	11th to 20th	Day	51% 8% 16% 22% 3	4085
	21st to end	Day	49% 7% 16% 25% 3	4532
September	1st to 10th	Day	51% 7% 12% 21% 9%	2272
	11th to 20th	Day	53% 6% 12% 19% 10%	2090
	21st to end	Day	49% 8% 15% 20% 8%	2090
October	1st to 10th	Day	62% 7% 11% 15% 5%	3325
	11th to 20th	Day	52% 6% 13% 19% 10%	3068
	21st to end	Day	61% 7% 9% 17% 6%	3092
November	1st to 10th	Day	62% 6% 14% 12% 5%	1732
	11th to 20th	Day	65% 8% 10% 12% 5%	1520
	21st to end	Day	68% 5% 12% 9% 5%	1463
December	1st to 10th	Day	70% 7% 10% 10% 4	1330
	11th to 20th	Day	70% 7% 9% 9% 4	1667
	21st to end	Day	73% 6% 9% 10% 2	2442
January	1st to 10th	Night	72% 6% 6% 9% 5% 2	4739
	11th to 20th	Night	67% 9% 11% 9% 4	4471
	21st to end	Night	67% 8% 11% 10% 3 1	4884
February	1st to 10th	Night	72% 6% 9% 8% 4 1	2530
	11th to 20th	Night	69% 8% 9% 10% 3	2393
	21st to end	Night	67% 6% 10% 10% 6%	1884
March	1st to 10th	Night	67% 6% 9% 13% 4 1	3708
	11th to 20th	Night	70% 7% 10% 10% 3	3480
	21st to end	Night	73% 5% 7% 11% 3	3815
April	1st to 10th	Night	67% 6% 8% 11% 7% 1	1881
	11th to 20th	Night	64% 6% 8% 13% 8% 1	1688
	21st to end	Night	66% 6% 8% 12% 8%	1710
May	1st to 10th	Night	73% 5% 9% 9% 4	2850
	11th to 20th	Night	72% 5% 6% 12% 5%	2467
	21st to end	Night	67% 7% 10% 10% 6%	2413
June	1st to 10th	Night	69% 6% 8% 12% 5%	1330
	11th to 20th	Night	60% 8% 14% 13% 5%	1330
	21st to end	Night	59% 8% 14% 14% 4	1330
July	1st to 10th	Night	65% 7% 10% 14% 4	2186
	11th to 20th	Night	57% 14% 16% 10% 3	2203
	21st to end	Night	44% 8% 20% 24% 4	2663
August	1st to 10th	Night	53% 9% 18% 17% 3	2727
	11th to 20th	Night	50% 6% 18% 22% 3	2818
	21st to end	Night	53% 7% 14% 23% 3	3134
September	1st to 10th	Night	51% 9% 12% 20% 7% 1	1904
	11th to 20th	Night	57% 7% 13% 14% 9%	2090
	21st to end	Night	53% 7% 14% 18% 7%	2090
October	1st to 10th	Night	62% 7% 14% 13% 3	3640
	11th to 20th	Night	50% 6% 16% 18% 9%	3859
	21st to end	Night	58% 6% 13% 17% 6%	4467
November	1st to 10th	Night	62% 7% 13% 12% 5%	2564
	11th to 20th	Night	64% 8% 11% 12% 3 1	2667
	21st to end	Night	63% 7% 14% 11% 5% 1	2713
December	1st to 10th	Night	69% 7% 8% 11% 4	2850
	11th to 20th	Night	75% 6% 8% 6% 4	3533
	21st to end	Night	66% 7% 11% 13% 2	5225

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	29% 23% 32% 12% 3 1	370
	11th to 20th	Day	27% 26% 30% 12% 3 1	370
	21st to end	Day	26% 25% 33% 13% 2	407
February	1st to 10th	Day	27% 24% 29% 17% 3 1	370
	11th to 20th	Day	27% 31% 30% 10% 2	366
	21st to end	Day	20% 31% 31% 15% 3	307
March	1st to 10th	Day	29% 28% 30% 9% 3 1	370
	11th to 20th	Day	23% 24% 30% 17% 3 3	370
	21st to end	Day	30% 24% 27% 13% 5% 1	407
April	1st to 10th	Day	32% 21% 28% 14% 4	484
	11th to 20th	Day	32% 19% 26% 15% 7% 1	639
	21st to end	Day	32% 19% 29% 16% 4	650
May	1st to 10th	Day	31% 19% 25% 17% 6% 2	653
	11th to 20th	Day	25% 14% 30% 20% 8% 2	674
	21st to end	Day	26% 18% 31% 19% 5% 1	735
June	1st to 10th	Day	40% 11% 25% 17% 6% 1	680
	11th to 20th	Day	31% 10% 29% 21% 7% 1	680
	21st to end	Day	26% 10% 29% 25% 7% 3	680
July	1st to 10th	Day	26% 9% 34% 21% 9% 2	670
	11th to 20th	Day	23% 8% 33% 25% 10% 1	668
	21st to end	Day	23% 11% 30% 25% 10% 1	740
August	1st to 10th	Day	24% 9% 30% 24% 9% 3	675
	11th to 20th	Day	23% 9% 29% 27% 11% 1	667
	21st to end	Day	22% 11% 27% 27% 12% 1	748
September	1st to 10th	Day	21% 11% 27% 28% 11% 2	522
	11th to 20th	Day	27% 14% 29% 22% 7% 1	390
	21st to end	Day	22% 18% 32% 19% 8% 1	390
October	1st to 10th	Day	25% 13% 32% 22% 7% 1	390
	11th to 20th	Day	29% 16% 28% 16% 9% 1	390
	21st to end	Day	29% 24% 25% 16% 4 2	429
November	1st to 10th	Day	27% 23% 28% 17% 4 1	395
	11th to 20th	Day	29% 22% 28% 16% 6% 1	370
	21st to end	Day	31% 29% 26% 10% 4	370
December	1st to 10th	Day	27% 23% 28% 17% 5%	370
	11th to 20th	Day	32% 26% 28% 10% 2	370
	21st to end	Day	27% 21% 33% 15% 4 1	407
January	1st to 10th	Night	28% 21% 34% 13% 4	850
	11th to 20th	Night	28% 22% 34% 13% 4	850
	21st to end	Night	25% 22% 33% 16% 2	935
February	1st to 10th	Night	26% 26% 33% 13% 2	850
	11th to 20th	Night	31% 22% 33% 11% 3	827
	21st to end	Night	23% 23% 31% 19% 4	628
March	1st to 10th	Night	24% 24% 34% 13% 3	746
	11th to 20th	Night	22% 19% 29% 24% 6%	570
	21st to end	Night	33% 19% 28% 17% 3	627
April	1st to 10th	Night	29% 19% 30% 15% 6% 1	570
	11th to 20th	Night	31% 17% 29% 18% 4	564
	21st to end	Night	33% 15% 30% 18% 4 1	570
May	1st to 10th	Night	30% 12% 28% 22% 6% 1	570
	11th to 20th	Night	30% 10% 31% 20% 8% 1	562
	21st to end	Night	28% 13% 32% 22% 4	616
June	1st to 10th	Night	34% 10% 27% 22% 6%	570
	11th to 20th	Night	31% 9% 27% 25% 7% 1	570
	21st to end	Night	26% 10% 34% 22% 7% 1	570
July	1st to 10th	Night	25% 7% 37% 25% 6% 1	556
	11th to 20th	Night	24% 7% 37% 26% 6%	552
	21st to end	Night	24% 7% 35% 27% 7%	623
August	1st to 10th	Night	27% 5% 29% 30% 8%	568
	11th to 20th	Night	26% 6% 29% 32% 7% 1	562
	21st to end	Night	24% 10% 30% 28% 8%	627
September	1st to 10th	Night	22% 10% 31% 29% 8% 1	570
	11th to 20th	Night	29% 11% 29% 26% 5% 1	570
	21st to end	Night	26% 14% 29% 25% 7%	570
October	1st to 10th	Night	26% 14% 32% 22% 7%	620
	11th to 20th	Night	29% 15% 28% 20% 7%	713
	21st to end	Night	31% 20% 26% 18% 5%	946
November	1st to 10th	Night	29% 21% 29% 17% 4	880
	11th to 20th	Night	29% 18% 29% 19% 5%	853
	21st to end	Night	26% 24% 32% 13% 4	850
December	1st to 10th	Night	27% 23% 28% 16% 5%	850
	11th to 20th	Night	34% 25% 28% 11% 2	850
	21st to end	Night	27% 21% 30% 18% 3 1	935

Page generated at 2024-11-08 07:44:46. Version ac07

Copyright © 2024 Attilla Danko.