Bracebridge
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bracebridge clear sky chart from 2005-11-06 to 2024-11-05.

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	17% 11% 4 8% 5% 4 4 3 5% 6% 32%	102230
	Night	17% 13% 5% 9% 5% 4 4 3 4 6% 30%	96808
Transparency	Day	52% 6% 11% 20% 10% 1	105825
	Night	54% 6% 11% 19% 10% 1	101303
Seeing	Day	25% 13% 31% 20% 9% 3	14894
	Night	24% 11% 29% 25% 10% 1	23644

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	15% 23% 11% 13% 4 4 2 1 3 3 19%	2517
	11th to 20th	Day	12% 18% 9% 18% 10% 6% 4 3 4 4 13%	2628
	21st to end	Day	18% 21% 8% 14% 6% 4 3 2 3 4 16%	3124
February	1st to 10th	Day	12% 21% 7% 16% 7% 6% 4 2 4 3 18%	1710
	11th to 20th	Day	14% 16% 6% 13% 7% 5% 4 3 4 5% 24%	1663
	21st to end	Day	17% 19% 6% 11% 6% 5% 5% 3 4 4 20%	1431
March	1st to 10th	Day	18% 16% 5% 8% 5% 4 3 3 5% 6% 27%	3432
	11th to 20th	Day	10% 19% 7% 10% 6% 5% 4 3 5% 5% 25%	3480
	21st to end	Day	15% 11% 4 7% 4 4 4 3 4 5% 39%	3815
April	1st to 10th	Day	20% 14% 3 7% 5% 4 4 3 4 6% 28%	2261
	11th to 20th	Day	23% 11% 2 6% 5% 4 4 3 4 5% 34%	2346
	21st to end	Day	23% 11% 4 6% 4 4 3 3 4 5% 33%	2470
May	1st to 10th	Day	20% 8% 3 8% 4 4 6% 4 5% 7% 31%	4192
	11th to 20th	Day	15% 9% 3 6% 4 4 4 4 6% 9% 36%	4398
	21st to end	Day	17% 6% 2 5% 4 4 4 4 4 7% 42%	4837
June	1st to 10th	Day	19% 8% 2 7% 5% 4 4 4 6% 7% 34%	2660
	11th to 20th	Day	15% 6% 3 6% 5% 5% 5% 4 7% 8% 36%	2816
	21st to end	Day	19% 8% 2 6% 5% 4 4 4 5% 8% 35%	2850
July	1st to 10th	Day	14% 6% 2 6% 4 5% 5% 5% 7% 9% 35%	4760
	11th to 20th	Day	14% 6% 2 6% 4 4 4 4 5% 7% 43%	4472
	21st to end	Day	10% 6% 2 6% 4 4 4 4 6% 8% 46%	4640
August	1st to 10th	Day	15% 7% 3 8% 5% 5% 5% 4 7% 8% 35%	4104
	11th to 20th	Day	17% 7% 3 6% 4 4 5% 5% 7% 9% 34%	4044
	21st to end	Day	10% 5% 2 6% 5% 5% 5% 4 6% 9% 44%	4378
September	1st to 10th	Day	15% 7% 2 7% 4 4 5% 3 6% 6% 39%	2280
	11th to 20th	Day	14% 6% 2 5% 5% 4 4 3 5% 7% 44%	2188
	21st to end	Day	19% 9% 3 7% 4 4 4 3 4 6% 35%	2041
October	1st to 10th	Day	22% 8% 2 7% 5% 4 4 3 4 6% 33%	1900
	11th to 20th	Day	26% 10% 4 9% 6% 4 5% 3 4 7% 23%	1900
	21st to end	Day	31% 11% 4 9% 5% 4 3 3 4 5% 22%	2090
November	1st to 10th	Day	19% 14% 3 8% 5% 4 5% 3 5% 7% 27%	1565
	11th to 20th	Day	17% 17% 5% 10% 6% 4 5% 4 5% 5% 22%	1520
	21st to end	Day	21% 22% 5% 10% 6% 4 4 3 5% 4 16%	1520
December	1st to 10th	Day	19% 28% 6% 10% 4 3 4 3 3 4 16%	1520
	11th to 20th	Day	19% 23% 5% 12% 5% 4 3 2 3 3 20%	1906
	21st to end	Day	25% 21% 7% 13% 5% 4 3 2 3 3 13%	2772
January	1st to 10th	Night	17% 23% 10% 14% 5% 5% 4 2 3 3 13%	4429
	11th to 20th	Night	14% 16% 6% 18% 8% 6% 5% 4 4 5% 14%	4330
	21st to end	Night	18% 19% 8% 12% 6% 6% 5% 3 4 4 16%	4532
February	1st to 10th	Night	13% 19% 7% 13% 8% 6% 4 4 4 5% 18%	2470
	11th to 20th	Night	12% 17% 7% 12% 7% 5% 4 3 4 4 24%	2403
	21st to end	Night	16% 17% 5% 10% 7% 6% 4 3 4 4 23%	2022
March	1st to 10th	Night	16% 13% 4 11% 6% 4 4 3 4 5% 30%	3408
	11th to 20th	Night	12% 17% 7% 9% 5% 4 4 4 4 5% 28%	3479
	21st to end	Night	15% 9% 5% 7% 5% 4 4 4 5% 6% 35%	3817
April	1st to 10th	Night	21% 14% 4 6% 5% 3 4 3 4 6% 29%	1919
	11th to 20th	Night	20% 10% 3 7% 4 4 4 3 5% 5% 36%	1800
	21st to end	Night	20% 9% 3 7% 6% 5% 4 4 4 6% 32%	1710
May	1st to 10th	Night	18% 6% 3 6% 4 4 5% 3 5% 8% 38%	2747
	11th to 20th	Night	16% 8% 2 5% 4 4 4 4 6% 8% 39%	2495
	21st to end	Night	12% 6% 2 6% 4 4 4 4 4 9% 43%	2738
June	1st to 10th	Night	16% 9% 3 7% 5% 4 4 4 6% 6% 36%	1520
	11th to 20th	Night	12% 7% 2 6% 4 4 3 4 6% 9% 42%	1359
	21st to end	Night	15% 8% 3 6% 5% 4 4 5% 5% 8% 37%	1330
July	1st to 10th	Night	10% 7% 3 7% 5% 5% 4 4 6% 7% 43%	2210
	11th to 20th	Night	17% 5% 2 5% 3 4 3 3 5% 6% 46%	2484
	21st to end	Night	10% 6% 2 5% 4 3 4 3 5% 7% 50%	2896
August	1st to 10th	Night	11% 6% 2 5% 4 4 4 4 7% 7% 45%	2825
	11th to 20th	Night	16% 7% 3 6% 4 4 4 3 4 6% 44%	2785
	21st to end	Night	15% 5% 2 5% 4 4 4 3 5% 7% 48%	3244
September	1st to 10th	Night	13% 6% 2 6% 4 3 3 4 6% 7% 45%	1900
	11th to 20th	Night	14% 5% 2 5% 4 4 3 4 4 7% 50%	1989
	21st to end	Night	19% 7% 3 6% 4 4 4 3 5% 6% 41%	2138
October	1st to 10th	Night	18% 8% 2 7% 5% 4 5% 3 5% 6% 36%	2280
	11th to 20th	Night	24% 11% 3 8% 5% 4 4 3 5% 5% 27%	2280
	21st to end	Night	26% 14% 4 9% 5% 4 3 3 3 5% 24%	2508
November	1st to 10th	Night	21% 13% 3 7% 4 4 4 3 4 6% 32%	2609
	11th to 20th	Night	18% 17% 5% 8% 5% 4 4 3 5% 6% 25%	2660
	21st to end	Night	23% 18% 6% 9% 5% 4 4 4 4 6% 17%	2660
December	1st to 10th	Night	21% 24% 6% 11% 5% 4 4 2 4 4 14%	2660
	11th to 20th	Night	18% 23% 8% 13% 5% 3 4 3 3 4 17%	3288
	21st to end	Night	25% 22% 7% 13% 5% 4 3 2 3 4 11%	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	72% 5% 8% 9% 6%	2518
	11th to 20th	Day	74% 6% 7% 7% 6%	2628
	21st to end	Day	73% 5% 7% 8% 6% 1	3124
February	1st to 10th	Day	72% 4 7% 12% 4 1	1710
	11th to 20th	Day	64% 5% 9% 13% 8% 1	1672
	21st to end	Day	68% 4 7% 13% 7%	1431
March	1st to 10th	Day	58% 6% 14% 10% 10%	3435
	11th to 20th	Day	60% 6% 11% 15% 7% 1	3480
	21st to end	Day	46% 6% 10% 20% 15% 2	3815
April	1st to 10th	Day	57% 5% 9% 18% 9% 2	2261
	11th to 20th	Day	53% 5% 8% 21% 13% 1	2346
	21st to end	Day	55% 5% 8% 18% 12% 3	2470
May	1st to 10th	Day	49% 8% 10% 21% 11% 1	4204
	11th to 20th	Day	43% 8% 13% 25% 10% 1	4402
	21st to end	Day	42% 6% 13% 19% 16% 3	4837
June	1st to 10th	Day	49% 7% 9% 21% 13%	2660
	11th to 20th	Day	42% 8% 12% 23% 14% 2	2816
	21st to end	Day	47% 7% 13% 21% 11% 1	2850
July	1st to 10th	Day	43% 8% 15% 23% 11% 1	4686
	11th to 20th	Day	38% 7% 14% 31% 10%	4396
	21st to end	Day	35% 6% 11% 31% 16% 1	4492
August	1st to 10th	Day	45% 7% 14% 23% 10% 1	4091
	11th to 20th	Day	44% 8% 15% 25% 8%	4083
	21st to end	Day	35% 7% 13% 34% 10% 1	4378
September	1st to 10th	Day	43% 7% 14% 25% 11% 1	2280
	11th to 20th	Day	39% 7% 13% 29% 12% 1	2188
	21st to end	Day	50% 7% 11% 24% 9%	2041
October	1st to 10th	Day	47% 5% 13% 24% 10% 1	3160
	11th to 20th	Day	52% 7% 12% 21% 8%	3140
	21st to end	Day	60% 6% 12% 17% 5%	3428
November	1st to 10th	Day	55% 7% 13% 19% 5%	1565
	11th to 20th	Day	62% 8% 11% 12% 5% 1	1520
	21st to end	Day	70% 5% 11% 10% 3	1520
December	1st to 10th	Day	73% 4 9% 10% 3 1	1520
	11th to 20th	Day	70% 5% 6% 11% 7%	1906
	21st to end	Day	77% 4 5% 10% 4	2772
January	1st to 10th	Night	76% 5% 7% 8% 4	4429
	11th to 20th	Night	72% 8% 8% 7% 4 1	4330
	21st to end	Night	71% 8% 7% 8% 5% 1	4532
February	1st to 10th	Night	69% 5% 9% 12% 5% 1	2470
	11th to 20th	Night	62% 6% 8% 16% 7%	2405
	21st to end	Night	64% 5% 9% 15% 7%	2022
March	1st to 10th	Night	55% 5% 13% 15% 10% 1	3418
	11th to 20th	Night	57% 7% 14% 14% 7% 1	3480
	21st to end	Night	45% 9% 10% 22% 13% 1	3817
April	1st to 10th	Night	57% 4 8% 18% 10% 2	1919
	11th to 20th	Night	49% 6% 7% 22% 15% 2	1800
	21st to end	Night	53% 6% 9% 15% 15% 2	1710
May	1st to 10th	Night	42% 7% 14% 22% 13% 2	2754
	11th to 20th	Night	40% 9% 14% 23% 13% 1	2496
	21st to end	Night	36% 8% 12% 25% 17% 2	2739
June	1st to 10th	Night	46% 8% 10% 21% 14% 1	1520
	11th to 20th	Night	38% 6% 13% 24% 19% 1	1359
	21st to end	Night	45% 6% 14% 22% 11% 1	1330
July	1st to 10th	Night	40% 7% 14% 23% 15% 2	2175
	11th to 20th	Night	38% 5% 12% 32% 12%	2438
	21st to end	Night	33% 6% 11% 34% 16% 1	2803
August	1st to 10th	Night	36% 6% 16% 26% 16% 1	2814
	11th to 20th	Night	41% 6% 17% 24% 12% 1	2812
	21st to end	Night	35% 6% 12% 34% 12% 1	3244
September	1st to 10th	Night	37% 7% 16% 26% 12% 1	1900
	11th to 20th	Night	34% 6% 16% 30% 13%	1989
	21st to end	Night	44% 6% 12% 27% 11%	2138
October	1st to 10th	Night	39% 5% 11% 27% 18%	3800
	11th to 20th	Night	50% 5% 15% 21% 8%	3779
	21st to end	Night	56% 5% 15% 17% 6%	4120
November	1st to 10th	Night	54% 6% 12% 21% 7%	2609
	11th to 20th	Night	59% 7% 12% 14% 7% 1	2660
	21st to end	Night	68% 7% 11% 11% 3	2660
December	1st to 10th	Night	74% 6% 8% 9% 4	2660
	11th to 20th	Night	70% 7% 8% 10% 5%	3288
	21st to end	Night	78% 5% 6% 8% 3	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	26% 21% 34% 12% 7% 1	180
	11th to 20th	Day	25% 21% 38% 11% 5% 1	213
	21st to end	Day	30% 13% 37% 15% 4	297
February	1st to 10th	Day	31% 26% 33% 7% 4	270
	11th to 20th	Day	27% 24% 40% 7% 1	270
	21st to end	Day	39% 24% 30% 7%	234
March	1st to 10th	Day	26% 17% 40% 14% 3	460
	11th to 20th	Day	24% 19% 35% 17% 4 1	460
	21st to end	Day	34% 13% 32% 15% 6%	506
April	1st to 10th	Day	28% 19% 30% 15% 6% 1	460
	11th to 20th	Day	38% 15% 22% 14% 8% 3	452
	21st to end	Day	35% 14% 30% 13% 7% 1	460
May	1st to 10th	Day	28% 11% 30% 20% 6% 4	463
	11th to 20th	Day	21% 15% 30% 21% 10% 3	487
	21st to end	Day	21% 13% 31% 21% 12% 2	529
June	1st to 10th	Day	24% 12% 32% 25% 6% 2	490
	11th to 20th	Day	18% 13% 30% 25% 12% 2	646
	21st to end	Day	23% 10% 36% 22% 7% 2	680
July	1st to 10th	Day	14% 8% 33% 29% 12% 3	671
	11th to 20th	Day	18% 8% 26% 28% 13% 6%	502
	21st to end	Day	14% 9% 32% 28% 12% 5%	532
August	1st to 10th	Day	17% 5% 28% 29% 14% 6%	486
	11th to 20th	Day	17% 5% 25% 29% 17% 8%	479
	21st to end	Day	17% 8% 31% 25% 14% 6%	539
September	1st to 10th	Day	18% 9% 30% 22% 14% 7%	490
	11th to 20th	Day	15% 7% 26% 24% 19% 10%	490
	21st to end	Day	23% 11% 25% 26% 13% 2	490
October	1st to 10th	Day	28% 11% 26% 17% 14% 4	490
	11th to 20th	Day	30% 13% 33% 17% 5% 2	490
	21st to end	Day	39% 16% 29% 14% 3	539
November	1st to 10th	Day	33% 17% 32% 15% 3	221
	11th to 20th	Day	31% 23% 29% 12% 5%	180
	21st to end	Day	38% 18% 33% 10% 1	180
December	1st to 10th	Day	36% 13% 34% 14% 2 1	180
	11th to 20th	Day	37% 24% 21% 14% 3 1	180
	21st to end	Day	39% 21% 29% 9% 2 1	198
January	1st to 10th	Night	31% 16% 30% 18% 5%	760
	11th to 20th	Night	32% 15% 29% 18% 5% 1	760
	21st to end	Night	23% 10% 36% 23% 8% 1	836
February	1st to 10th	Night	24% 19% 34% 20% 3	760
	11th to 20th	Night	22% 17% 35% 19% 6%	743
	21st to end	Night	28% 18% 30% 20% 4	628
March	1st to 10th	Night	22% 17% 36% 21% 3	760
	11th to 20th	Night	24% 16% 34% 21% 5% 1	760
	21st to end	Night	22% 13% 31% 25% 8%	836
April	1st to 10th	Night	29% 13% 31% 21% 6%	760
	11th to 20th	Night	28% 12% 29% 21% 9% 1	676
	21st to end	Night	26% 10% 30% 25% 9% 1	570
May	1st to 10th	Night	23% 4 27% 32% 12% 1	523
	11th to 20th	Night	19% 9% 29% 30% 13%	374
	21st to end	Night	13% 6% 33% 34% 14%	411
June	1st to 10th	Night	22% 5% 30% 32% 11% 1	380
	11th to 20th	Night	17% 7% 25% 39% 12%	380
	21st to end	Night	19% 5% 23% 39% 13% 1	380
July	1st to 10th	Night	12% 3 20% 48% 17% 1	370
	11th to 20th	Night	15% 4 24% 37% 19% 1	368
	21st to end	Night	12% 4 22% 40% 21% 1	511
August	1st to 10th	Night	13% 3 17% 38% 27% 2	567
	11th to 20th	Night	14% 3 17% 37% 26% 3	564
	21st to end	Night	18% 5% 25% 29% 22% 2	695
September	1st to 10th	Night	16% 6% 26% 32% 18% 3	760
	11th to 20th	Night	17% 4 23% 30% 22% 4	760
	21st to end	Night	22% 6% 20% 33% 16% 3	760
October	1st to 10th	Night	22% 10% 27% 27% 13% 1	760
	11th to 20th	Night	30% 11% 29% 20% 9% 1	760
	21st to end	Night	33% 14% 29% 20% 4	836
November	1st to 10th	Night	31% 10% 26% 26% 6% 1	760
	11th to 20th	Night	28% 18% 29% 19% 6% 1	760
	21st to end	Night	35% 13% 27% 21% 4 1	760
December	1st to 10th	Night	35% 17% 30% 14% 4	760
	11th to 20th	Night	31% 16% 34% 14% 3 1	760
	21st to end	Night	35% 13% 30% 18% 3	836

Page generated at 2024-11-03 02:11:24. Version ac07

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