Oshawa
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Oshawa clear sky chart from 2005-11-06 to 2024-11-04.

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	14% 9% 3 7% 5% 5% 5% 4 6% 7% 35%	101496
	Night	16% 9% 3 7% 5% 5% 5% 4 5% 7% 35%	97520
Transparency	Day	45% 8% 14% 22% 11% 1	105097
	Night	46% 6% 14% 21% 11% 1	102007
Seeing	Day	18% 11% 27% 26% 14% 4	14452
	Night	20% 8% 27% 30% 13% 2	23776

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	17% 13% 3 9% 6% 4 4 3 4 6% 31%	2517
	11th to 20th	Day	11% 18% 6% 15% 8% 5% 5% 4 5% 5% 18%	2682
	21st to end	Day	21% 18% 6% 10% 6% 5% 4 3 4 5% 18%	3124
February	1st to 10th	Day	15% 14% 4 12% 7% 6% 6% 4 5% 5% 22%	1710
	11th to 20th	Day	13% 14% 5% 12% 6% 5% 4 3 5% 6% 27%	1663
	21st to end	Day	18% 13% 5% 9% 6% 5% 4 3 5% 5% 29%	1456
March	1st to 10th	Day	20% 9% 3 8% 5% 4 4 3 5% 6% 32%	3432
	11th to 20th	Day	11% 14% 5% 8% 5% 6% 6% 4 6% 6% 30%	3480
	21st to end	Day	16% 8% 3 7% 4 4 4 3 5% 6% 40%	3815
April	1st to 10th	Day	17% 11% 3 7% 6% 4 4 4 6% 7% 30%	2270
	11th to 20th	Day	20% 8% 3 6% 4 4 4 4 5% 6% 36%	2292
	21st to end	Day	19% 8% 2 7% 5% 5% 4 4 5% 6% 34%	2470
May	1st to 10th	Day	17% 7% 2 8% 4 5% 5% 4 6% 8% 33%	4161
	11th to 20th	Day	14% 9% 3 8% 6% 4 4 4 7% 9% 31%	4398
	21st to end	Day	11% 6% 2 5% 5% 4 4 3 6% 8% 47%	4837
June	1st to 10th	Day	15% 6% 2 7% 5% 4 5% 4 7% 9% 36%	2660
	11th to 20th	Day	11% 5% 2 5% 4 4 5% 4 7% 9% 42%	2660
	21st to end	Day	13% 6% 2 5% 4 4 5% 4 7% 9% 41%	2660
July	1st to 10th	Day	9% 4 2 5% 4 5% 5% 4 8% 10% 44%	4440
	11th to 20th	Day	10% 4 2 5% 4 4 5% 4 6% 9% 47%	4440
	21st to end	Day	7% 5% 2 6% 5% 5% 6% 5% 7% 9% 43%	4598
August	1st to 10th	Day	15% 7% 3 6% 4 4 5% 4 6% 7% 40%	4104
	11th to 20th	Day	11% 6% 3 7% 5% 5% 4 4 7% 10% 40%	4044
	21st to end	Day	8% 5% 2 6% 4 4 5% 4 6% 10% 45%	4316
September	1st to 10th	Day	12% 5% 2 5% 4 4 4 4 7% 7% 45%	2280
	11th to 20th	Day	11% 4 2 5% 3 5% 4 4 6% 7% 49%	2209
	21st to end	Day	13% 6% 2 7% 5% 5% 5% 4 5% 8% 40%	2025
October	1st to 10th	Day	16% 7% 3 6% 5% 5% 5% 4 5% 6% 37%	1900
	11th to 20th	Day	19% 8% 2 8% 5% 4 4 4 6% 7% 32%	1900
	21st to end	Day	22% 10% 3 8% 6% 5% 4 3 5% 6% 27%	2090
November	1st to 10th	Day	15% 8% 3 8% 6% 5% 5% 4 6% 7% 34%	1625
	11th to 20th	Day	15% 10% 4 8% 8% 5% 5% 4 7% 7% 26%	1520
	21st to end	Day	21% 11% 4 9% 6% 4 4 4 4 8% 26%	1520
December	1st to 10th	Day	17% 15% 5% 10% 7% 6% 6% 4 6% 6% 19%	1520
	11th to 20th	Day	19% 13% 4 8% 5% 3 5% 4 6% 7% 26%	1906
	21st to end	Day	29% 15% 4 12% 6% 5% 5% 2 4 4 14%	2772
January	1st to 10th	Night	19% 14% 4 9% 5% 5% 5% 4 5% 6% 24%	4429
	11th to 20th	Night	15% 13% 4 13% 8% 6% 5% 5% 5% 9% 18%	4276
	21st to end	Night	21% 13% 5% 9% 6% 5% 4 4 5% 6% 22%	4532
February	1st to 10th	Night	15% 14% 4 10% 7% 5% 5% 4 6% 5% 24%	2470
	11th to 20th	Night	15% 13% 5% 9% 6% 5% 4 4 6% 6% 28%	2403
	21st to end	Night	16% 10% 4 9% 6% 5% 4 4 6% 6% 30%	1993
March	1st to 10th	Night	19% 10% 3 7% 5% 5% 5% 3 5% 6% 32%	3408
	11th to 20th	Night	14% 11% 4 9% 5% 5% 4 4 5% 6% 34%	3479
	21st to end	Night	17% 7% 2 5% 4 4 5% 4 5% 6% 43%	3817
April	1st to 10th	Night	19% 10% 3 6% 5% 5% 4 3 5% 6% 34%	1910
	11th to 20th	Night	16% 7% 3 8% 5% 5% 5% 3 5% 6% 38%	1852
	21st to end	Night	18% 8% 3 7% 4 4 5% 3 6% 7% 35%	1710
May	1st to 10th	Night	19% 7% 3 6% 4 4 4 4 5% 6% 39%	2779
	11th to 20th	Night	15% 7% 3 7% 5% 4 6% 5% 6% 8% 33%	2495
	21st to end	Night	9% 4 2 5% 4 4 4 4 5% 8% 50%	2738
June	1st to 10th	Night	13% 5% 2 6% 5% 4 5% 4 7% 8% 41%	1520
	11th to 20th	Night	9% 4 2 7% 5% 4 5% 4 6% 9% 44%	1520
	21st to end	Night	13% 5% 2 5% 4 4 4 6% 7% 8% 42%	1520
July	1st to 10th	Night	6% 5% 2 5% 4 5% 5% 4 6% 9% 49%	2520
	11th to 20th	Night	11% 5% 1 5% 3 3 4 4 6% 8% 50%	2520
	21st to end	Night	9% 4 2 5% 4 3 4 4 7% 8% 51%	2951
August	1st to 10th	Night	10% 5% 2 6% 4 4 4 3 6% 8% 48%	2825
	11th to 20th	Night	12% 5% 2 5% 3 4 4 3 5% 8% 50%	2785
	21st to end	Night	10% 5% 2 6% 4 4 5% 4 6% 8% 47%	3307
September	1st to 10th	Night	10% 5% 2 5% 4 4 6% 3 6% 7% 47%	1900
	11th to 20th	Night	11% 4 2 4 3 4 3 3 5% 8% 54%	1966
	21st to end	Night	16% 6% 2 7% 5% 4 4 3 4 6% 43%	2153
October	1st to 10th	Night	16% 6% 3 7% 4 4 3 4 5% 7% 40%	2280
	11th to 20th	Night	20% 9% 3 7% 5% 4 5% 4 5% 6% 33%	2280
	21st to end	Night	22% 8% 3 7% 5% 5% 5% 4 5% 6% 31%	2508
November	1st to 10th	Night	17% 7% 2 6% 5% 5% 4 3 6% 6% 38%	2522
	11th to 20th	Night	17% 10% 3 6% 6% 5% 5% 5% 5% 7% 31%	2660
	21st to end	Night	21% 10% 3 7% 5% 5% 4 4 6% 7% 26%	2660
December	1st to 10th	Night	19% 15% 4 9% 6% 5% 5% 4 4 6% 22%	2660
	11th to 20th	Night	17% 15% 4 9% 6% 5% 5% 4 6% 6% 23%	3288
	21st to end	Night	31% 14% 4 8% 5% 5% 5% 4 5% 6% 15%	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	54% 6% 21% 12% 6% 1	2518
	11th to 20th	Day	69% 6% 13% 8% 3	2682
	21st to end	Day	68% 6% 11% 10% 4	3124
February	1st to 10th	Day	63% 6% 12% 14% 4 1	1710
	11th to 20th	Day	57% 7% 11% 17% 7% 1	1672
	21st to end	Day	56% 6% 12% 18% 7%	1456
March	1st to 10th	Day	51% 6% 15% 18% 10%	3435
	11th to 20th	Day	49% 9% 15% 16% 9% 1	3480
	21st to end	Day	42% 7% 11% 22% 16% 2	3815
April	1st to 10th	Day	51% 7% 11% 18% 11% 2	2270
	11th to 20th	Day	47% 7% 9% 21% 14% 1	2292
	21st to end	Day	48% 6% 11% 20% 12% 3	2470
May	1st to 10th	Day	46% 8% 12% 19% 13% 2	4173
	11th to 20th	Day	47% 9% 16% 18% 9% 1	4402
	21st to end	Day	33% 7% 16% 26% 14% 3	4837
June	1st to 10th	Day	42% 8% 13% 22% 14% 1	2660
	11th to 20th	Day	36% 8% 14% 25% 15% 2	2660
	21st to end	Day	37% 8% 16% 25% 14% 1	2660
July	1st to 10th	Day	32% 8% 15% 27% 16% 2	4370
	11th to 20th	Day	30% 9% 15% 35% 10% 1	4365
	21st to end	Day	32% 10% 16% 25% 16% 1	4451
August	1st to 10th	Day	41% 8% 15% 23% 13% 1	4091
	11th to 20th	Day	37% 7% 17% 29% 10%	4083
	21st to end	Day	31% 9% 15% 34% 10% 1	4316
September	1st to 10th	Day	36% 8% 15% 29% 11% 1	2280
	11th to 20th	Day	32% 7% 15% 31% 15% 1	2209
	21st to end	Day	40% 8% 15% 26% 10%	2025
October	1st to 10th	Day	36% 6% 16% 28% 14% 1	3160
	11th to 20th	Day	36% 7% 19% 24% 14%	3140
	21st to end	Day	48% 8% 16% 21% 6%	3428
November	1st to 10th	Day	47% 8% 14% 21% 9% 1	1625
	11th to 20th	Day	54% 7% 15% 15% 8% 1	1520
	21st to end	Day	57% 7% 15% 17% 4	1520
December	1st to 10th	Day	64% 7% 14% 13% 2	1520
	11th to 20th	Day	57% 9% 15% 13% 6%	1906
	21st to end	Day	73% 6% 10% 9% 2	2772
January	1st to 10th	Night	60% 7% 15% 14% 3 1	4429
	11th to 20th	Night	63% 11% 16% 7% 3 1	4276
	21st to end	Night	63% 5% 16% 11% 4 1	4532
February	1st to 10th	Night	60% 6% 12% 18% 4 1	2470
	11th to 20th	Night	56% 6% 11% 18% 9%	2405
	21st to end	Night	52% 6% 14% 19% 7% 1	1993
March	1st to 10th	Night	52% 5% 12% 23% 7% 1	3418
	11th to 20th	Night	48% 6% 15% 20% 10% 1	3480
	21st to end	Night	39% 7% 10% 25% 18% 2	3817
April	1st to 10th	Night	50% 6% 9% 21% 13% 1	1910
	11th to 20th	Night	46% 6% 10% 18% 17% 2	1852
	21st to end	Night	47% 5% 11% 20% 15% 2	1710
May	1st to 10th	Night	45% 5% 13% 18% 15% 3	2786
	11th to 20th	Night	44% 7% 17% 19% 10% 2	2496
	21st to end	Night	31% 6% 15% 25% 21% 2	2739
June	1st to 10th	Night	39% 7% 12% 23% 16% 3	1520
	11th to 20th	Night	36% 6% 12% 22% 22% 2	1520
	21st to end	Night	37% 8% 13% 25% 16% 1	1520
July	1st to 10th	Night	30% 6% 16% 25% 21% 2	2480
	11th to 20th	Night	30% 6% 15% 34% 14% 1	2472
	21st to end	Night	28% 8% 15% 29% 17% 1	2857
August	1st to 10th	Night	35% 4 15% 29% 15% 2	2814
	11th to 20th	Night	33% 6% 16% 32% 12% 1	2812
	21st to end	Night	32% 6% 14% 32% 14% 1	3307
September	1st to 10th	Night	34% 6% 16% 28% 14% 1	1900
	11th to 20th	Night	30% 5% 14% 32% 19%	1966
	21st to end	Night	42% 5% 13% 27% 12% 1	2153
October	1st to 10th	Night	33% 5% 11% 28% 22% 1	3800
	11th to 20th	Night	41% 6% 15% 29% 9%	3779
	21st to end	Night	39% 7% 15% 28% 10% 1	4120
November	1st to 10th	Night	45% 5% 13% 24% 12% 1	2522
	11th to 20th	Night	52% 5% 15% 17% 10% 1	2660
	21st to end	Night	55% 7% 18% 15% 4	2660
December	1st to 10th	Night	62% 5% 14% 14% 4	2660
	11th to 20th	Night	61% 7% 14% 14% 4	3288
	21st to end	Night	69% 7% 13% 8% 2	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	25% 14% 33% 18% 9% 1	180
	11th to 20th	Day	25% 22% 31% 15% 5% 1	227
	21st to end	Day	25% 20% 33% 18% 4 1	297
February	1st to 10th	Day	24% 23% 35% 13% 5%	270
	11th to 20th	Day	22% 21% 41% 14% 1	270
	21st to end	Day	32% 19% 35% 13% 1	268
March	1st to 10th	Day	23% 16% 34% 21% 6%	460
	11th to 20th	Day	23% 17% 32% 22% 6%	460
	21st to end	Day	29% 12% 29% 21% 8% 1	506
April	1st to 10th	Day	21% 13% 36% 24% 5%	460
	11th to 20th	Day	27% 13% 27% 22% 9% 3	452
	21st to end	Day	24% 13% 34% 19% 9% 2	460
May	1st to 10th	Day	21% 10% 27% 26% 10% 5%	463
	11th to 20th	Day	16% 8% 25% 32% 16% 4	487
	21st to end	Day	12% 5% 23% 32% 20% 6%	529
June	1st to 10th	Day	15% 9% 28% 31% 16% 2	490
	11th to 20th	Day	13% 6% 25% 33% 21% 3	490
	21st to end	Day	15% 7% 26% 32% 16% 5%	490
July	1st to 10th	Day	9% 4 19% 35% 25% 8%	485
	11th to 20th	Day	14% 4 19% 33% 23% 8%	484
	21st to end	Day	8% 4 24% 39% 19% 6%	532
August	1st to 10th	Day	10% 5% 20% 33% 21% 10%	486
	11th to 20th	Day	10% 5% 19% 30% 28% 8%	479
	21st to end	Day	12% 4 21% 31% 23% 9%	539
September	1st to 10th	Day	12% 7% 22% 30% 19% 10%	490
	11th to 20th	Day	10% 4 19% 28% 24% 16%	490
	21st to end	Day	15% 8% 28% 26% 16% 7%	490
October	1st to 10th	Day	19% 9% 26% 26% 15% 5%	490
	11th to 20th	Day	18% 16% 32% 24% 8% 1	490
	21st to end	Day	27% 12% 32% 21% 8% 1	539
November	1st to 10th	Day	21% 17% 26% 26% 10% 1	281
	11th to 20th	Day	18% 19% 36% 21% 6% 1	180
	21st to end	Day	29% 12% 36% 18% 5% 1	180
December	1st to 10th	Day	21% 16% 34% 19% 7% 2	180
	11th to 20th	Day	29% 18% 28% 17% 7%	180
	21st to end	Day	26% 22% 36% 15% 1	198
January	1st to 10th	Night	25% 14% 37% 17% 6%	760
	11th to 20th	Night	29% 13% 32% 22% 4 1	760
	21st to end	Night	21% 10% 34% 27% 7%	836
February	1st to 10th	Night	21% 15% 38% 23% 3	760
	11th to 20th	Night	22% 13% 36% 23% 6%	743
	21st to end	Night	22% 12% 39% 22% 4	628
March	1st to 10th	Night	21% 12% 34% 27% 5% 1	760
	11th to 20th	Night	22% 12% 33% 27% 5% 1	760
	21st to end	Night	21% 9% 30% 28% 11%	836
April	1st to 10th	Night	24% 9% 32% 29% 6%	760
	11th to 20th	Night	18% 9% 32% 29% 10% 2	728
	21st to end	Night	21% 7% 27% 33% 12%	570
May	1st to 10th	Night	21% 3 27% 29% 18% 2	542
	11th to 20th	Night	15% 4 27% 38% 16%	374
	21st to end	Night	11% 3 19% 42% 22% 2	411
June	1st to 10th	Night	15% 3 22% 42% 18% 1	380
	11th to 20th	Night	9% 5% 21% 42% 22% 1	380
	21st to end	Night	12% 5% 21% 40% 21% 1	380
July	1st to 10th	Night	5% 4 16% 45% 28% 3	370
	11th to 20th	Night	11% 4 16% 37% 30% 2	368
	21st to end	Night	10% 2 13% 47% 25% 2	540
August	1st to 10th	Night	10% 2 12% 41% 31% 4	567
	11th to 20th	Night	8% 2 13% 41% 30% 5%	564
	21st to end	Night	13% 3 18% 37% 27% 3	732
September	1st to 10th	Night	12% 5% 18% 36% 24% 5%	760
	11th to 20th	Night	14% 4 17% 30% 28% 8%	760
	21st to end	Night	21% 5% 18% 31% 21% 5%	760
October	1st to 10th	Night	18% 5% 27% 28% 20% 2	760
	11th to 20th	Night	22% 11% 27% 27% 11% 1	760
	21st to end	Night	26% 7% 29% 30% 6% 1	836
November	1st to 10th	Night	21% 10% 24% 32% 11% 1	755
	11th to 20th	Night	23% 12% 29% 27% 7% 2	760
	21st to end	Night	25% 10% 31% 27% 7%	760
December	1st to 10th	Night	29% 13% 31% 22% 5%	760
	11th to 20th	Night	23% 12% 36% 24% 4 1	760
	21st to end	Night	32% 10% 35% 21% 2	836

Page generated at 2024-11-01 22:47:43. Version ac07

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