Haliburton Forest Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Haliburton Forest Observatory clear sky chart from 2005-11-06 to 2024-03-23.

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	18% 12% 5% 8% 6% 3 4 4 5% 6% 28%	78968
	Night	17% 14% 6% 9% 7% 3 4 4 4 6% 27%	80897
Transparency	Day	57% 4 10% 19% 9% 1	78675
	Night	59% 4 10% 18% 9% 1	80726
Seeing	Day	25% 15% 31% 19% 8% 2	13820
	Night	24% 14% 29% 23% 9% 1	22906

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% 22% 9% 17% 7% 3 2 2 3 3 18%	2517
	11th to 20th	Day	12% 15% 11% 18% 11% 4 4 3 4 3 14%	2552
	21st to end	Day	18% 20% 10% 13% 7% 3 3 3 2 3 17%	3124
February	1st to 10th	Day	13% 17% 8% 14% 11% 4 4 3 3 4 18%	1710
	11th to 20th	Day	13% 15% 8% 13% 8% 4 5% 3 3 6% 23%	1663
	21st to end	Day	16% 18% 7% 9% 7% 4 6% 4 3 4 21%	1451
March	1st to 10th	Day	15% 14% 5% 10% 7% 4 4 4 5% 6% 26%	2054
	11th to 20th	Day	12% 16% 7% 10% 9% 4 5% 4 4 4 26%	2090
	21st to end	Day	17% 12% 5% 7% 6% 3 4 4 4 5% 35%	2208
April	1st to 10th	Day	21% 14% 5% 7% 6% 2 4 4 5% 6% 26%	2160
	11th to 20th	Day	22% 11% 4 5% 4 3 4 4 4 5% 34%	2184
	21st to end	Day	21% 13% 4 6% 5% 2 4 3 4 5% 33%	2340
May	1st to 10th	Day	18% 9% 4 6% 6% 3 5% 4 5% 7% 33%	2427
	11th to 20th	Day	18% 9% 4 6% 6% 3 4 4 5% 7% 35%	2478
	21st to end	Day	15% 7% 3 6% 6% 3 5% 5% 6% 7% 38%	2725
June	1st to 10th	Day	22% 8% 4 6% 5% 4 4 4 6% 7% 31%	2520
	11th to 20th	Day	16% 7% 3 5% 5% 3 4 6% 7% 8% 36%	2583
	21st to end	Day	18% 7% 3 6% 5% 4 6% 5% 6% 8% 33%	2700
July	1st to 10th	Day	15% 5% 3 5% 5% 3 4 5% 7% 9% 39%	2638
	11th to 20th	Day	13% 7% 3 7% 5% 4 5% 6% 5% 8% 37%	2520
	21st to end	Day	14% 6% 3 6% 6% 4 5% 6% 6% 9% 34%	2708
August	1st to 10th	Day	14% 7% 3 7% 7% 4 6% 5% 6% 7% 33%	2327
	11th to 20th	Day	15% 6% 3 6% 6% 3 6% 6% 6% 7% 36%	2303
	21st to end	Day	15% 8% 2 5% 6% 4 6% 6% 7% 8% 34%	2464
September	1st to 10th	Day	17% 7% 3 5% 5% 3 5% 5% 6% 7% 37%	2160
	11th to 20th	Day	16% 6% 3 5% 6% 2 4 4 5% 7% 41%	2116
	21st to end	Day	20% 8% 4 6% 4 3 4 5% 5% 6% 35%	1905
October	1st to 10th	Day	22% 9% 3 7% 6% 3 5% 4 4 7% 31%	1800
	11th to 20th	Day	29% 13% 3 7% 6% 3 4 4 5% 5% 21%	1800
	21st to end	Day	32% 14% 5% 7% 5% 2 4 4 3 5% 19%	1967
November	1st to 10th	Day	19% 15% 4 6% 5% 3 4 5% 4 7% 29%	1536
	11th to 20th	Day	19% 17% 7% 10% 6% 3 4 4 5% 4 20%	1520
	21st to end	Day	21% 23% 8% 9% 6% 3 4 4 3 5% 15%	1520
December	1st to 10th	Day	19% 25% 9% 10% 6% 3 4 3 4 4 13%	1520
	11th to 20th	Day	17% 22% 10% 11% 7% 2 3 3 3 3 19%	1906
	21st to end	Day	23% 21% 9% 12% 6% 2 3 2 3 4 14%	2772
January	1st to 10th	Night	17% 20% 10% 15% 7% 3 3 4 4 5% 13%	4429
	11th to 20th	Night	13% 16% 7% 17% 14% 5% 5% 4 4 5% 12%	4404
	21st to end	Night	17% 18% 9% 14% 7% 4 5% 4 3 3 15%	4532
February	1st to 10th	Night	12% 18% 7% 12% 10% 4 5% 4 5% 5% 17%	2470
	11th to 20th	Night	13% 13% 8% 13% 8% 3 4 5% 3 4 25%	2403
	21st to end	Night	15% 17% 6% 11% 8% 4 5% 3 4 6% 21%	2001
March	1st to 10th	Night	14% 12% 6% 10% 7% 3 4 4 3 5% 32%	2112
	11th to 20th	Night	12% 13% 7% 9% 7% 4 4 4 5% 5% 30%	2089
	21st to end	Night	14% 11% 4 7% 6% 3 3 4 5% 6% 37%	2192
April	1st to 10th	Night	21% 14% 6% 7% 4 3 4 4 4 6% 28%	1800
	11th to 20th	Night	18% 11% 4 6% 5% 3 4 4 4 5% 36%	1741
	21st to end	Night	20% 10% 4 7% 7% 3 4 4 4 5% 31%	1620
May	1st to 10th	Night	20% 7% 2 5% 5% 3 4 5% 6% 7% 36%	1530
	11th to 20th	Night	16% 7% 3 5% 4 3 4 5% 6% 7% 41%	1415
	21st to end	Night	11% 5% 2 4 4 3 5% 5% 6% 9% 44%	1550
June	1st to 10th	Night	17% 7% 4 6% 5% 3 5% 5% 5% 7% 35%	1440
	11th to 20th	Night	14% 6% 3 5% 4 3 4 4 5% 6% 44%	1368
	21st to end	Night	16% 8% 3 5% 6% 4 4 4 7% 8% 36%	1260
July	1st to 10th	Night	10% 5% 2 5% 5% 4 4 5% 6% 7% 47%	1318
	11th to 20th	Night	13% 7% 2 6% 5% 2 5% 5% 5% 7% 44%	1440
	21st to end	Night	11% 4 3 5% 4 3 4 5% 5% 9% 45%	1607
August	1st to 10th	Night	11% 5% 2 4 4 3 4 5% 6% 8% 48%	1611
	11th to 20th	Night	12% 5% 2 5% 5% 3 5% 6% 6% 7% 44%	1598
	21st to end	Night	14% 6% 3 6% 4 3 4 5% 5% 9% 41%	1872
September	1st to 10th	Night	11% 7% 3 5% 5% 3 4 5% 6% 7% 44%	1800
	11th to 20th	Night	15% 6% 2 5% 5% 3 4 4 5% 7% 45%	1840
	21st to end	Night	20% 7% 2 5% 6% 3 3 4 4 5% 41%	2054
October	1st to 10th	Night	19% 8% 3 6% 5% 3 4 4 4 6% 36%	2160
	11th to 20th	Night	25% 13% 4 6% 6% 3 4 3 4 5% 26%	2160
	21st to end	Night	26% 15% 5% 7% 6% 3 4 3 4 5% 23%	2387
November	1st to 10th	Night	20% 14% 4 7% 5% 3 4 4 5% 6% 29%	2542
	11th to 20th	Night	19% 14% 5% 8% 6% 3 5% 4 4 6% 25%	2660
	21st to end	Night	22% 19% 6% 9% 7% 3 4 4 4 5% 17%	2660
December	1st to 10th	Night	20% 25% 9% 11% 7% 3 4 4 4 4 12%	2660
	11th to 20th	Night	18% 22% 9% 12% 7% 3 3 3 3 4 18%	3288
	21st to end	Night	24% 22% 8% 11% 8% 2 3 3 3 4 12%	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	74% 2 8% 9% 6%	2518
	11th to 20th	Day	77% 2 5% 9% 5% 1	2552
	21st to end	Day	74% 3 6% 10% 6% 1	3124
February	1st to 10th	Day	72% 3 6% 13% 5% 1	1710
	11th to 20th	Day	64% 3 9% 12% 9% 2	1672
	21st to end	Day	67% 4 7% 12% 9%	1451
March	1st to 10th	Day	60% 4 12% 14% 9% 2	2057
	11th to 20th	Day	61% 3 8% 15% 9% 2	2090
	21st to end	Day	53% 3 8% 18% 13% 5%	2208
April	1st to 10th	Day	59% 4 8% 18% 9% 2	2160
	11th to 20th	Day	53% 3 7% 23% 13% 1	2184
	21st to end	Day	56% 2 7% 19% 12% 4	2340
May	1st to 10th	Day	52% 4 8% 21% 13% 3	2427
	11th to 20th	Day	49% 4 7% 24% 14% 1	2482
	21st to end	Day	45% 6% 13% 20% 14% 3	2725
June	1st to 10th	Day	53% 4 9% 22% 12% 1	2520
	11th to 20th	Day	44% 5% 11% 24% 13% 2	2583
	21st to end	Day	48% 5% 13% 22% 10% 1	2700
July	1st to 10th	Day	39% 6% 12% 29% 12% 2	2567
	11th to 20th	Day	43% 6% 12% 28% 10% 1	2445
	21st to end	Day	46% 6% 11% 27% 9%	2557
August	1st to 10th	Day	48% 6% 13% 23% 9% 1	2314
	11th to 20th	Day	46% 5% 15% 25% 8% 1	2303
	21st to end	Day	46% 6% 15% 23% 10% 1	2464
September	1st to 10th	Day	45% 5% 13% 25% 11% 1	2160
	11th to 20th	Day	42% 5% 13% 28% 11% 1	2116
	21st to end	Day	50% 6% 11% 26% 8%	1905
October	1st to 10th	Day	54% 4 10% 21% 10% 1	1800
	11th to 20th	Day	66% 5% 11% 12% 6% 1	1800
	21st to end	Day	69% 3 8% 14% 5%	1967
November	1st to 10th	Day	57% 3 13% 20% 6% 1	1536
	11th to 20th	Day	65% 4 11% 13% 6% 1	1520
	21st to end	Day	75% 3 8% 9% 4 1	1520
December	1st to 10th	Day	76% 3 8% 9% 4 1	1520
	11th to 20th	Day	73% 3 5% 11% 8% 1	1906
	21st to end	Day	77% 2 5% 12% 4	2772
January	1st to 10th	Night	76% 3 7% 11% 3	4429
	11th to 20th	Night	77% 2 7% 8% 5% 1	4404
	21st to end	Night	75% 3 6% 9% 6% 1	4532
February	1st to 10th	Night	68% 4 9% 13% 6% 1	2470
	11th to 20th	Night	63% 3 7% 18% 8%	2405
	21st to end	Night	66% 3 7% 15% 7% 1	2001
March	1st to 10th	Night	57% 3 10% 16% 12% 2	2122
	11th to 20th	Night	57% 4 10% 18% 10% 2	2090
	21st to end	Night	48% 4 8% 22% 14% 3	2192
April	1st to 10th	Night	58% 3 7% 19% 11% 2	1800
	11th to 20th	Night	51% 4 6% 23% 15% 1	1741
	21st to end	Night	56% 3 7% 16% 15% 2	1620
May	1st to 10th	Night	47% 4 11% 20% 16% 3	1530
	11th to 20th	Night	42% 4 9% 26% 17% 2	1416
	21st to end	Night	36% 5% 16% 23% 17% 3	1551
June	1st to 10th	Night	49% 5% 11% 21% 13% 2	1440
	11th to 20th	Night	39% 4 13% 27% 17% 1	1368
	21st to end	Night	45% 7% 15% 23% 10% 1	1260
July	1st to 10th	Night	34% 6% 12% 26% 20% 1	1280
	11th to 20th	Night	39% 5% 13% 31% 12% 1	1392
	21st to end	Night	36% 6% 14% 30% 13% 1	1518
August	1st to 10th	Night	34% 5% 18% 28% 13% 1	1600
	11th to 20th	Night	37% 6% 17% 28% 11% 1	1598
	21st to end	Night	40% 6% 15% 28% 10% 1	1872
September	1st to 10th	Night	37% 6% 16% 27% 13% 1	1800
	11th to 20th	Night	39% 5% 14% 30% 12%	1840
	21st to end	Night	46% 5% 11% 30% 9%	2054
October	1st to 10th	Night	49% 5% 11% 21% 14%	2160
	11th to 20th	Night	61% 4 12% 18% 5%	2160
	21st to end	Night	65% 4 9% 14% 8% 1	2387
November	1st to 10th	Night	57% 4 12% 20% 7%	2542
	11th to 20th	Night	61% 4 12% 16% 7% 1	2660
	21st to end	Night	70% 4 9% 12% 4	2660
December	1st to 10th	Night	77% 4 6% 9% 3	2660
	11th to 20th	Night	72% 3 6% 12% 6%	3288
	21st to end	Night	79% 2 5% 10% 4	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	23% 24% 34% 14% 3 1	180
	11th to 20th	Day	30% 13% 38% 14% 3 2	189
	21st to end	Day	26% 17% 36% 15% 4	297
February	1st to 10th	Day	29% 27% 34% 7% 2 1	270
	11th to 20th	Day	27% 29% 36% 7%	270
	21st to end	Day	38% 21% 30% 11%	263
March	1st to 10th	Day	25% 20% 36% 17% 2	460
	11th to 20th	Day	26% 20% 32% 16% 4 1	460
	21st to end	Day	31% 16% 31% 14% 6% 1	470
April	1st to 10th	Day	28% 19% 30% 16% 6% 1	420
	11th to 20th	Day	34% 19% 21% 15% 8% 3	412
	21st to end	Day	30% 15% 34% 13% 7% 1	420
May	1st to 10th	Day	26% 15% 29% 21% 6% 3	423
	11th to 20th	Day	24% 16% 30% 18% 9% 3	447
	21st to end	Day	21% 16% 30% 21% 9% 3	485
June	1st to 10th	Day	25% 12% 34% 23% 5% 1	450
	11th to 20th	Day	20% 14% 32% 22% 10% 2	513
	21st to end	Day	19% 15% 34% 22% 8% 2	630
July	1st to 10th	Day	15% 8% 33% 32% 10% 2	562
	11th to 20th	Day	17% 11% 30% 23% 15% 4	444
	21st to end	Day	15% 12% 33% 29% 9% 3	488
August	1st to 10th	Day	19% 7% 29% 27% 13% 6%	446
	11th to 20th	Day	16% 8% 25% 30% 16% 6%	439
	21st to end	Day	19% 10% 30% 22% 13% 5%	495
September	1st to 10th	Day	18% 11% 32% 20% 14% 5%	450
	11th to 20th	Day	18% 10% 26% 23% 16% 7%	450
	21st to end	Day	22% 14% 27% 21% 11% 4	450
October	1st to 10th	Day	29% 15% 24% 17% 13% 3	450
	11th to 20th	Day	35% 18% 29% 13% 3 2	450
	21st to end	Day	40% 15% 28% 13% 3	489
November	1st to 10th	Day	33% 19% 30% 15% 3	230
	11th to 20th	Day	31% 23% 29% 12% 3 1	180
	21st to end	Day	35% 21% 36% 6% 3	180
December	1st to 10th	Day	32% 19% 35% 12% 2	180
	11th to 20th	Day	36% 29% 21% 13% 1 1	180
	21st to end	Day	32% 25% 29% 10% 3 1	198
January	1st to 10th	Night	28% 18% 34% 16% 4	760
	11th to 20th	Night	30% 16% 32% 18% 4 1	760
	21st to end	Night	21% 15% 35% 21% 8% 1	836
February	1st to 10th	Night	24% 21% 33% 19% 3	760
	11th to 20th	Night	21% 21% 37% 18% 3	743
	21st to end	Night	25% 24% 29% 19% 4	628
March	1st to 10th	Night	22% 20% 35% 19% 4	760
	11th to 20th	Night	21% 18% 36% 19% 4 1	760
	21st to end	Night	20% 14% 35% 22% 8%	801
April	1st to 10th	Night	28% 15% 31% 20% 5%	720
	11th to 20th	Night	26% 16% 29% 20% 10%	677
	21st to end	Night	26% 10% 29% 23% 11%	540
May	1st to 10th	Night	25% 6% 28% 28% 12% 1	450
	11th to 20th	Night	19% 9% 35% 27% 10%	354
	21st to end	Night	14% 10% 33% 31% 12% 1	389
June	1st to 10th	Night	19% 9% 33% 30% 8% 1	360
	11th to 20th	Night	19% 8% 26% 37% 11% 1	360
	21st to end	Night	19% 7% 20% 40% 13% 1	360
July	1st to 10th	Night	9% 6% 26% 38% 20% 1	350
	11th to 20th	Night	15% 6% 26% 32% 20% 1	348
	21st to end	Night	12% 7% 26% 39% 17%	427
August	1st to 10th	Night	13% 5% 21% 36% 23% 3	537
	11th to 20th	Night	13% 6% 18% 37% 24% 3	534
	21st to end	Night	17% 7% 26% 29% 20% 2	684
September	1st to 10th	Night	14% 7% 28% 31% 17% 3	720
	11th to 20th	Night	19% 7% 22% 29% 19% 4	720
	21st to end	Night	24% 10% 21% 27% 15% 3	720
October	1st to 10th	Night	23% 11% 29% 23% 12% 1	720
	11th to 20th	Night	33% 13% 29% 18% 8% 1	720
	21st to end	Night	37% 14% 26% 19% 4	792
November	1st to 10th	Night	30% 14% 27% 22% 7%	740
	11th to 20th	Night	28% 18% 31% 16% 6% 1	760
	21st to end	Night	34% 15% 29% 19% 3 1	760
December	1st to 10th	Night	35% 19% 30% 13% 4	760
	11th to 20th	Night	26% 22% 34% 14% 3 1	760
	21st to end	Night	34% 18% 30% 16% 3 1	836

Page generated at 2024-03-19 23:31:07. Version ac07

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