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 2024-11-04.

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	17% 12% 4 9% 5% 4 4 3 5% 6% 30%	102020
	Night	16% 14% 5% 10% 5% 4 4 3 5% 6% 29%	96992
Transparency	Day	54% 4 10% 21% 9% 1	105604
	Night	56% 4 10% 19% 9% 1	101498
Seeing	Day	25% 15% 31% 19% 8% 2	14739
	Night	24% 14% 29% 23% 9% 1	23598

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% 8% 18% 5% 3 2 2 3 3 18%	2517
	11th to 20th	Day	12% 16% 11% 21% 8% 5% 4 3 4 3 14%	2552
	21st to end	Day	17% 21% 10% 14% 6% 4 3 2 3 3 17%	3124
February	1st to 10th	Day	12% 19% 8% 17% 8% 5% 4 3 3 4 18%	1710
	11th to 20th	Day	12% 16% 7% 14% 6% 5% 3 3 3 6% 23%	1663
	21st to end	Day	15% 19% 6% 11% 6% 6% 5% 3 4 4 20%	1451
March	1st to 10th	Day	17% 18% 4 9% 6% 4 3 3 5% 6% 25%	3388
	11th to 20th	Day	10% 18% 7% 13% 7% 5% 4 4 4 5% 24%	3480
	21st to end	Day	13% 11% 5% 8% 5% 4 4 3 4 5% 38%	3836
April	1st to 10th	Day	21% 16% 4 7% 5% 3 4 3 4 6% 27%	2280
	11th to 20th	Day	23% 12% 3 6% 4 3 4 3 4 5% 33%	2307
	21st to end	Day	21% 14% 4 7% 4 3 3 2 4 5% 33%	2470
May	1st to 10th	Day	19% 8% 4 8% 5% 4 5% 3 6% 7% 31%	4265
	11th to 20th	Day	16% 9% 3 7% 5% 4 4 4 6% 9% 34%	4398
	21st to end	Day	18% 7% 2 6% 4 4 4 4 5% 6% 40%	4837
June	1st to 10th	Day	22% 9% 3 7% 5% 4 4 4 6% 7% 30%	2660
	11th to 20th	Day	15% 8% 2 6% 5% 5% 5% 5% 7% 8% 35%	2727
	21st to end	Day	19% 8% 3 7% 5% 5% 5% 4 5% 7% 33%	2850
July	1st to 10th	Day	15% 7% 2 7% 6% 5% 5% 4 7% 10% 33%	4642
	11th to 20th	Day	14% 7% 2 6% 5% 5% 5% 4 5% 8% 40%	4440
	21st to end	Day	10% 7% 3 6% 5% 4 5% 4 6% 8% 44%	4752
August	1st to 10th	Day	15% 9% 3 9% 5% 5% 6% 4 6% 7% 31%	4104
	11th to 20th	Day	18% 7% 3 7% 4 5% 5% 5% 7% 7% 32%	4044
	21st to end	Day	10% 6% 2 6% 5% 5% 6% 5% 8% 10% 39%	4324
September	1st to 10th	Day	17% 8% 3 5% 5% 4 4 4 5% 7% 37%	2280
	11th to 20th	Day	15% 6% 2 6% 5% 3 4 3 5% 7% 43%	2233
	21st to end	Day	20% 9% 3 6% 4 3 5% 4 5% 5% 35%	2010
October	1st to 10th	Day	21% 9% 3 8% 5% 4 4 3 5% 6% 32%	1900
	11th to 20th	Day	28% 14% 3 8% 5% 4 4 3 5% 5% 22%	1900
	21st to end	Day	30% 14% 5% 8% 4 3 4 3 3 5% 20%	2076
November	1st to 10th	Day	18% 16% 3 7% 5% 3 4 4 4 6% 29%	1562
	11th to 20th	Day	18% 19% 6% 11% 5% 5% 4 3 5% 4 20%	1520
	21st to end	Day	21% 24% 7% 10% 5% 4 4 3 3 4 15%	1520
December	1st to 10th	Day	18% 27% 8% 11% 6% 3 3 3 4 4 13%	1520
	11th to 20th	Day	16% 24% 9% 13% 5% 3 3 3 3 3 19%	1906
	21st to end	Day	23% 22% 8% 14% 4 3 3 2 3 4 14%	2772
January	1st to 10th	Night	16% 21% 10% 16% 5% 4 3 3 4 5% 13%	4429
	11th to 20th	Night	13% 17% 7% 21% 10% 6% 4 3 4 4 12%	4404
	21st to end	Night	17% 19% 8% 15% 6% 7% 4 3 3 3 15%	4532
February	1st to 10th	Night	12% 20% 7% 13% 9% 5% 5% 3 5% 5% 17%	2470
	11th to 20th	Night	12% 15% 7% 14% 6% 4 4 4 4 4 25%	2403
	21st to end	Night	15% 18% 5% 12% 7% 5% 5% 2 5% 5% 21%	2001
March	1st to 10th	Night	16% 14% 5% 10% 6% 4 4 3 3 5% 28%	3451
	11th to 20th	Night	11% 20% 7% 10% 5% 4 4 3 5% 5% 25%	3479
	21st to end	Night	13% 10% 5% 8% 7% 4 4 4 6% 6% 33%	3795
April	1st to 10th	Night	21% 16% 4 7% 3 4 3 3 4 6% 28%	1900
	11th to 20th	Night	18% 12% 4 6% 4 4 4 3 4 5% 36%	1839
	21st to end	Night	20% 10% 4 9% 6% 4 4 3 4 5% 31%	1710
May	1st to 10th	Night	19% 8% 2 6% 5% 4 4 4 6% 6% 35%	2673
	11th to 20th	Night	16% 9% 3 6% 4 4 4 4 6% 7% 38%	2495
	21st to end	Night	13% 8% 2 6% 4 4 4 3 5% 8% 42%	2738
June	1st to 10th	Night	17% 9% 3 7% 5% 5% 4 4 5% 7% 34%	1520
	11th to 20th	Night	14% 7% 3 6% 4 4 4 4 6% 7% 43%	1444
	21st to end	Night	17% 9% 2 6% 5% 5% 3 3 7% 7% 35%	1330
July	1st to 10th	Night	10% 7% 3 8% 5% 6% 5% 4 5% 7% 40%	2320
	11th to 20th	Night	17% 7% 2 6% 4 3 4 3 4 6% 43%	2520
	21st to end	Night	10% 7% 2 5% 4 3 4 3 5% 7% 49%	2798
August	1st to 10th	Night	12% 5% 2 6% 4 4 4 4 6% 8% 47%	2825
	11th to 20th	Night	17% 8% 3 7% 4 4 4 4 5% 5% 41%	2785
	21st to end	Night	14% 4 2 5% 3 3 4 3 5% 9% 46%	3298
September	1st to 10th	Night	12% 7% 2 6% 4 4 4 3 6% 6% 45%	1900
	11th to 20th	Night	14% 6% 1 5% 3 4 4 3 4 7% 47%	1943
	21st to end	Night	20% 8% 2 6% 4 4 3 3 4 5% 41%	2169
October	1st to 10th	Night	19% 8% 3 7% 4 4 4 3 4 6% 37%	2280
	11th to 20th	Night	24% 14% 4 7% 5% 4 4 3 4 5% 27%	2280
	21st to end	Night	25% 16% 5% 7% 5% 4 4 2 4 5% 23%	2520
November	1st to 10th	Night	19% 15% 4 8% 4 4 3 3 5% 5% 29%	2589
	11th to 20th	Night	19% 16% 5% 8% 5% 4 5% 3 4 6% 25%	2660
	21st to end	Night	21% 20% 5% 10% 6% 4 4 3 4 5% 17%	2660
December	1st to 10th	Night	19% 26% 8% 12% 5% 4 3 3 4 3 12%	2660
	11th to 20th	Night	17% 24% 7% 13% 5% 3 2 2 3 4 17%	3288
	21st to end	Night	23% 23% 8% 13% 6% 3 3 2 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	61% 3 13% 11% 11% 1	3391
	11th to 20th	Day	63% 4 9% 15% 8% 1	3480
	21st to end	Day	48% 4 8% 22% 14% 3	3836
April	1st to 10th	Day	59% 4 8% 18% 9% 2	2280
	11th to 20th	Day	54% 3 6% 23% 12% 1	2307
	21st to end	Day	56% 2 7% 19% 12% 3	2470
May	1st to 10th	Day	52% 4 8% 24% 11% 2	4277
	11th to 20th	Day	47% 4 11% 28% 10% 1	4402
	21st to end	Day	44% 4 13% 19% 15% 4	4837
June	1st to 10th	Day	54% 4 9% 21% 12%	2660
	11th to 20th	Day	45% 5% 11% 24% 13% 2	2727
	21st to end	Day	49% 5% 13% 21% 10% 1	2850
July	1st to 10th	Day	45% 5% 14% 25% 10% 1	4571
	11th to 20th	Day	41% 5% 15% 30% 9%	4365
	21st to end	Day	37% 5% 11% 32% 14%	4601
August	1st to 10th	Day	51% 5% 13% 23% 8% 1	4091
	11th to 20th	Day	48% 5% 13% 26% 7%	4083
	21st to end	Day	38% 6% 14% 32% 10%	4324
September	1st to 10th	Day	45% 5% 13% 25% 11% 1	2280
	11th to 20th	Day	40% 5% 13% 29% 13% 1	2233
	21st to end	Day	50% 5% 10% 25% 9%	2010
October	1st to 10th	Day	50% 5% 11% 26% 8% 1	3160
	11th to 20th	Day	56% 4 10% 20% 10%	3140
	21st to end	Day	64% 4 11% 17% 4	3402
November	1st to 10th	Day	56% 3 13% 20% 6% 1	1562
	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	59% 3 10% 16% 11% 2	3461
	11th to 20th	Night	61% 3 11% 17% 7% 1	3480
	21st to end	Night	49% 5% 8% 24% 13% 2	3795
April	1st to 10th	Night	58% 3 7% 19% 11% 2	1900
	11th to 20th	Night	51% 4 6% 23% 15% 1	1839
	21st to end	Night	56% 3 7% 16% 15% 2	1710
May	1st to 10th	Night	48% 4 11% 23% 12% 2	2680
	11th to 20th	Night	45% 4 11% 28% 11% 1	2496
	21st to end	Night	41% 4 12% 25% 17% 2	2739
June	1st to 10th	Night	50% 5% 11% 20% 13% 2	1520
	11th to 20th	Night	39% 4 13% 27% 16% 1	1444
	21st to end	Night	46% 6% 14% 23% 10% 1	1330
July	1st to 10th	Night	43% 6% 14% 22% 15% 1	2282
	11th to 20th	Night	42% 4 11% 32% 10%	2472
	21st to end	Night	35% 5% 11% 33% 15% 1	2709
August	1st to 10th	Night	36% 4 17% 27% 15% 1	2814
	11th to 20th	Night	44% 5% 16% 25% 9% 1	2812
	21st to end	Night	35% 5% 13% 34% 12% 2	3298
September	1st to 10th	Night	37% 6% 15% 28% 12% 1	1900
	11th to 20th	Night	38% 4 14% 31% 14%	1943
	21st to end	Night	46% 4 11% 28% 11%	2169
October	1st to 10th	Night	41% 5% 10% 29% 16%	3800
	11th to 20th	Night	52% 4 13% 21% 10%	3779
	21st to end	Night	58% 4 16% 16% 6%	4144
November	1st to 10th	Night	57% 4 12% 20% 7%	2589
	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	27% 20% 32% 16% 4 1	460
	21st to end	Day	31% 17% 32% 14% 5% 1	506
April	1st to 10th	Day	29% 19% 29% 16% 6% 1	460
	11th to 20th	Day	37% 18% 20% 14% 7% 3	452
	21st to end	Day	30% 16% 33% 12% 8% 1	460
May	1st to 10th	Day	25% 15% 29% 21% 7% 3	463
	11th to 20th	Day	23% 15% 30% 19% 10% 3	487
	21st to end	Day	21% 16% 29% 21% 9% 3	529
June	1st to 10th	Day	25% 13% 33% 23% 5% 1	490
	11th to 20th	Day	20% 13% 34% 22% 9% 2	557
	21st to end	Day	22% 14% 33% 21% 8% 2	680
July	1st to 10th	Day	16% 8% 33% 31% 10% 2	608
	11th to 20th	Day	17% 12% 31% 23% 13% 4	484
	21st to end	Day	14% 11% 32% 29% 10% 3	532
August	1st to 10th	Day	19% 8% 29% 27% 12% 5%	486
	11th to 20th	Day	16% 8% 25% 29% 16% 5%	479
	21st to end	Day	18% 10% 31% 23% 13% 5%	539
September	1st to 10th	Day	19% 11% 32% 19% 13% 5%	490
	11th to 20th	Day	17% 9% 24% 23% 17% 10%	490
	21st to end	Day	23% 13% 26% 22% 11% 4	490
October	1st to 10th	Day	27% 15% 26% 17% 12% 3	490
	11th to 20th	Day	33% 19% 30% 14% 3 2	490
	21st to end	Day	38% 17% 29% 13% 3	532
November	1st to 10th	Day	33% 18% 31% 15% 3	238
	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%	836
April	1st to 10th	Night	29% 15% 31% 20% 5%	760
	11th to 20th	Night	26% 16% 29% 20% 9%	715
	21st to end	Night	26% 9% 30% 23% 11%	570
May	1st to 10th	Night	24% 7% 29% 28% 11% 1	475
	11th to 20th	Night	19% 9% 34% 28% 10%	374
	21st to end	Night	14% 11% 32% 32% 11% 1	411
June	1st to 10th	Night	19% 10% 32% 30% 8% 1	380
	11th to 20th	Night	18% 8% 26% 37% 11% 1	380
	21st to end	Night	21% 7% 19% 39% 12% 1	380
July	1st to 10th	Night	9% 6% 27% 38% 19% 1	370
	11th to 20th	Night	15% 6% 26% 33% 20% 1	368
	21st to end	Night	12% 6% 24% 39% 18%	451
August	1st to 10th	Night	13% 4 21% 37% 23% 2	567
	11th to 20th	Night	14% 6% 17% 36% 23% 3	564
	21st to end	Night	17% 7% 25% 29% 20% 2	723
September	1st to 10th	Night	15% 7% 28% 31% 16% 3	760
	11th to 20th	Night	18% 6% 21% 28% 22% 4	760
	21st to end	Night	25% 9% 20% 28% 15% 2	760
October	1st to 10th	Night	23% 11% 29% 23% 12% 1	760
	11th to 20th	Night	31% 13% 28% 19% 8% 1	760
	21st to end	Night	36% 14% 26% 19% 4	836
November	1st to 10th	Night	30% 14% 27% 22% 7%	755
	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 2024-11-01 22:47:47. Version ac07

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