Port Hope Simpson Community Hall
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Port Hope Simpson Community Hall clear sky chart from 2005-11-06 to 2026-10-29.

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	20% 14% 4 8% 5% 4 4 3 5% 6% 26%	151737
	Night	19% 15% 4 8% 5% 4 4 3 4 5% 28%	140637
Transparency	Day	58% 6% 12% 17% 7% 1	155099
	Night	57% 6% 11% 17% 8% 1	145386
Seeing	Day	31% 15% 29% 18% 6% 2	20735
	Night	29% 15% 30% 20% 6% 1	27042

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% 19% 8% 11% 3 3 3 2 3 4 27%	3857
	11th to 20th	Day	17% 21% 7% 9% 5% 3 3 2 3 4 26%	4286
	21st to end	Day	7% 12% 3 5% 3 5% 4 4 5% 6% 46%	5157
February	1st to 10th	Day	11% 12% 5% 8% 5% 5% 4 4 4 6% 35%	1680
	11th to 20th	Day	14% 22% 6% 9% 5% 3 4 2 4 5% 25%	1738
	21st to end	Day	13% 18% 4 7% 4 4 4 3 4 6% 31%	1730
March	1st to 10th	Day	13% 14% 5% 10% 5% 6% 6% 3 4 4 31%	4574
	11th to 20th	Day	15% 24% 7% 11% 5% 4 3 3 3 4 21%	4824
	21st to end	Day	23% 16% 6% 10% 5% 4 3 2 4 4 23%	5998
April	1st to 10th	Day	20% 20% 6% 9% 6% 4 4 2 5% 4 20%	2520
	11th to 20th	Day	18% 20% 6% 9% 5% 4 3 3 4 5% 24%	2689
	21st to end	Day	23% 18% 5% 8% 5% 4 3 3 4 4 23%	2814
May	1st to 10th	Day	28% 19% 4 8% 5% 4 3 3 4 4 18%	8236
	11th to 20th	Day	24% 20% 5% 9% 4 4 4 3 3 5% 19%	8776
	21st to end	Day	22% 17% 4 8% 5% 4 4 3 4 5% 23%	9682
June	1st to 10th	Day	33% 13% 4 7% 5% 4 4 3 4 5% 18%	3210
	11th to 20th	Day	32% 12% 3 7% 5% 4 4 4 5% 6% 19%	3360
	21st to end	Day	28% 10% 3 7% 5% 4 4 3 6% 6% 24%	3360
July	1st to 10th	Day	21% 8% 2 6% 4 4 5% 4 6% 7% 33%	9450
	11th to 20th	Day	21% 10% 3 8% 5% 5% 5% 4 6% 7% 26%	8874
	21st to end	Day	14% 9% 3 8% 6% 6% 6% 5% 7% 8% 28%	9282
August	1st to 10th	Day	21% 12% 4 8% 5% 5% 5% 4 5% 7% 23%	6484
	11th to 20th	Day	24% 11% 3 9% 5% 5% 5% 4 6% 7% 21%	6302
	21st to end	Day	18% 9% 3 7% 4 4 5% 3 5% 7% 36%	6594
September	1st to 10th	Day	25% 7% 2 7% 4 4 4 3 5% 7% 31%	2530
	11th to 20th	Day	25% 10% 3 7% 5% 5% 4 3 5% 6% 27%	2372
	21st to end	Day	23% 10% 3 7% 5% 4 5% 3 3 6% 29%	2310
October	1st to 10th	Day	23% 14% 3 8% 4 4 4 3 4 6% 27%	2193
	11th to 20th	Day	25% 14% 3 8% 5% 4 3 3 4 5% 25%	1890
	21st to end	Day	24% 16% 3 6% 4 4 4 2 5% 5% 28%	2052
November	1st to 10th	Day	18% 14% 3 6% 5% 4 3 3 5% 6% 31%	1734
	11th to 20th	Day	20% 13% 2 7% 5% 4 4 3 5% 5% 32%	1470
	21st to end	Day	21% 18% 4 5% 4 3 3 3 4 4 30%	1470
December	1st to 10th	Day	11% 16% 5% 10% 5% 6% 3 3 3 6% 32%	2360
	11th to 20th	Day	17% 15% 6% 8% 4 4 4 4 4 6% 29%	2698
	21st to end	Day	18% 14% 5% 9% 6% 2 3 2 3 5% 33%	3181
January	1st to 10th	Night	18% 18% 5% 10% 4 3 4 3 4 4 26%	9060
	11th to 20th	Night	14% 22% 7% 10% 5% 4 4 3 4 4 24%	8613
	21st to end	Night	7% 12% 3 7% 4 3 4 3 5% 6% 46%	9056
February	1st to 10th	Night	11% 12% 5% 10% 5% 4 4 3 4 6% 37%	2940
	11th to 20th	Night	14% 20% 7% 11% 6% 4 3 2 4 4 25%	2763
	21st to end	Night	12% 17% 5% 8% 5% 3 4 3 5% 5% 32%	2076
March	1st to 10th	Night	15% 14% 4 10% 5% 4 5% 4 4 5% 31%	5486
	11th to 20th	Night	14% 22% 7% 9% 5% 4 3 3 4 4 26%	5355
	21st to end	Night	23% 14% 4 9% 5% 5% 4 3 4 5% 24%	5175
April	1st to 10th	Night	20% 18% 6% 10% 5% 4 4 3 4 4 22%	2100
	11th to 20th	Night	21% 16% 5% 7% 5% 3 4 3 5% 5% 26%	1880
	21st to end	Night	23% 16% 5% 7% 4 3 3 3 4 4 27%	1805
May	1st to 10th	Night	33% 20% 5% 7% 3 3 3 2 4 5% 14%	4692
	11th to 20th	Night	27% 16% 4 9% 4 3 3 3 3 4 23%	4112
	21st to end	Night	26% 16% 4 7% 4 4 4 3 4 4 25%	4524
June	1st to 10th	Night	31% 14% 3 7% 4 4 4 2 4 4 21%	1427
	11th to 20th	Night	30% 15% 3 8% 4 4 4 4 5% 5% 17%	1260
	21st to end	Night	27% 10% 3 6% 4 4 4 3 5% 5% 28%	1260
July	1st to 10th	Night	21% 9% 3 6% 5% 5% 4 3 6% 7% 31%	3540
	11th to 20th	Night	20% 9% 3 7% 4 4 5% 4 6% 6% 30%	4038
	21st to end	Night	14% 9% 3 9% 6% 6% 5% 4 6% 7% 32%	4826
August	1st to 10th	Night	19% 12% 4 8% 5% 5% 5% 4 6% 7% 27%	3686
	11th to 20th	Night	26% 11% 3 7% 4 4 5% 3 5% 7% 26%	3763
	21st to end	Night	14% 6% 3 7% 5% 5% 5% 4 6% 7% 37%	4553
September	1st to 10th	Night	21% 8% 3 6% 5% 4 4 4 5% 7% 33%	2088
	11th to 20th	Night	24% 11% 3 7% 4 3 4 3 6% 5% 29%	2248
	21st to end	Night	23% 11% 4 7% 4 4 4 2 6% 6% 30%	2310
October	1st to 10th	Night	24% 13% 3 8% 4 4 4 2 5% 6% 29%	2423
	11th to 20th	Night	24% 14% 4 6% 4 4 4 3 4 6% 27%	2730
	21st to end	Night	24% 17% 4 7% 4 4 3 3 3 5% 25%	2965
November	1st to 10th	Night	20% 13% 3 7% 5% 4 5% 3 5% 6% 29%	2781
	11th to 20th	Night	22% 13% 3 6% 4 4 4 3 4 5% 31%	3150
	21st to end	Night	21% 19% 5% 6% 4 3 3 3 4 4 28%	3150
December	1st to 10th	Night	12% 13% 6% 11% 6% 5% 5% 3 5% 4 29%	5050
	11th to 20th	Night	18% 12% 5% 10% 6% 5% 4 3 5% 5% 27%	5731
	21st to end	Night	16% 14% 6% 10% 6% 4 3 3 4 6% 29%	8021

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	62% 4 8% 16% 9% 1	3858
	11th to 20th	Day	63% 4 11% 12% 9%	4311
	21st to end	Day	38% 4 11% 25% 20% 3	5157
February	1st to 10th	Day	51% 3 9% 20% 14% 2	1680
	11th to 20th	Day	61% 4 6% 16% 11% 1	1745
	21st to end	Day	53% 5% 7% 18% 15% 1	1730
March	1st to 10th	Day	55% 5% 6% 15% 16% 2	4578
	11th to 20th	Day	68% 4 6% 9% 10% 3	4824
	21st to end	Day	65% 4 5% 12% 12% 1	5998
April	1st to 10th	Day	66% 5% 6% 12% 9% 2	2520
	11th to 20th	Day	62% 5% 10% 14% 9%	2689
	21st to end	Day	64% 4 10% 15% 6% 1	2814
May	1st to 10th	Day	69% 5% 9% 11% 5%	8249
	11th to 20th	Day	67% 6% 9% 15% 4	8780
	21st to end	Day	62% 6% 13% 17% 2	9683
June	1st to 10th	Day	68% 6% 10% 10% 5%	3210
	11th to 20th	Day	65% 6% 12% 12% 4	3360
	21st to end	Day	59% 7% 12% 17% 6%	3360
July	1st to 10th	Day	47% 7% 13% 24% 8%	9370
	11th to 20th	Day	53% 8% 14% 17% 7% 1	8791
	21st to end	Day	48% 9% 16% 22% 5%	9078
August	1st to 10th	Day	58% 8% 17% 15% 2	6470
	11th to 20th	Day	58% 9% 15% 14% 4	6344
	21st to end	Day	47% 6% 16% 25% 7%	6594
September	1st to 10th	Day	52% 5% 14% 20% 8% 1	2530
	11th to 20th	Day	58% 6% 12% 17% 7% 1	2372
	21st to end	Day	56% 6% 13% 19% 6% 1	2310
October	1st to 10th	Day	52% 7% 11% 23% 6%	3507
	11th to 20th	Day	61% 5% 14% 14% 6%	3012
	21st to end	Day	61% 6% 10% 14% 8% 1	3263
November	1st to 10th	Day	52% 5% 11% 20% 10% 1	1734
	11th to 20th	Day	54% 5% 13% 20% 8%	1470
	21st to end	Day	57% 4 10% 17% 12%	1470
December	1st to 10th	Day	52% 6% 10% 21% 10%	2360
	11th to 20th	Day	56% 9% 11% 15% 9% 1	2697
	21st to end	Day	54% 4 14% 16% 12% 1	3181
January	1st to 10th	Night	60% 5% 8% 16% 10% 2	9060
	11th to 20th	Night	62% 5% 12% 14% 6%	8662
	21st to end	Night	39% 4 9% 24% 19% 5%	9056
February	1st to 10th	Night	49% 4 11% 22% 13% 2	2940
	11th to 20th	Night	63% 4 9% 15% 8% 2	2767
	21st to end	Night	53% 4 9% 20% 13% 1	2076
March	1st to 10th	Night	55% 5% 8% 13% 17% 2	5495
	11th to 20th	Night	63% 4 5% 13% 13% 2	5356
	21st to end	Night	61% 6% 7% 15% 10% 1	5175
April	1st to 10th	Night	64% 5% 7% 12% 10% 2	2100
	11th to 20th	Night	59% 5% 10% 15% 10%	1880
	21st to end	Night	59% 4 12% 15% 8% 1	1805
May	1st to 10th	Night	73% 4 10% 9% 3	4697
	11th to 20th	Night	65% 5% 10% 14% 5%	4113
	21st to end	Night	64% 4 10% 19% 3	4525
June	1st to 10th	Night	65% 6% 9% 14% 6%	1427
	11th to 20th	Night	68% 7% 12% 10% 3	1260
	21st to end	Night	56% 8% 13% 18% 5%	1260
July	1st to 10th	Night	51% 7% 17% 20% 5%	3510
	11th to 20th	Night	50% 8% 12% 26% 5%	3998
	21st to end	Night	48% 8% 18% 22% 4	4716
August	1st to 10th	Night	55% 10% 20% 14% 2	3675
	11th to 20th	Night	57% 8% 19% 13% 3	3787
	21st to end	Night	44% 7% 17% 26% 5%	4552
September	1st to 10th	Night	49% 7% 17% 20% 7%	2088
	11th to 20th	Night	55% 6% 14% 19% 6% 1	2248
	21st to end	Night	54% 6% 15% 18% 6% 1	2310
October	1st to 10th	Night	62% 5% 10% 16% 6%	3891
	11th to 20th	Night	60% 7% 9% 15% 9%	4357
	21st to end	Night	60% 6% 12% 14% 8%	4715
November	1st to 10th	Night	54% 6% 13% 18% 9% 1	2781
	11th to 20th	Night	55% 5% 13% 20% 7% 1	3150
	21st to end	Night	60% 5% 10% 16% 10% 1	3150
December	1st to 10th	Night	54% 6% 11% 18% 10% 1	5050
	11th to 20th	Night	57% 8% 13% 12% 9% 1	5733
	21st to end	Night	56% 5% 12% 17% 9%	8021

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	27% 17% 28% 19% 6% 3	331
	11th to 20th	Day	22% 21% 32% 16% 7% 1	430
	21st to end	Day	21% 20% 33% 21% 4	473
February	1st to 10th	Day	19% 15% 39% 20% 5% 2	430
	11th to 20th	Day	25% 20% 36% 14% 3 2	426
	21st to end	Day	26% 19% 34% 14% 6% 1	355
March	1st to 10th	Day	26% 23% 28% 18% 5% 1	430
	11th to 20th	Day	27% 15% 30% 19% 7% 2	430
	21st to end	Day	29% 22% 30% 13% 4 1	567
April	1st to 10th	Day	33% 19% 29% 13% 5% 1	540
	11th to 20th	Day	28% 18% 30% 18% 5% 2	727
	21st to end	Day	30% 18% 25% 18% 7% 2	750
May	1st to 10th	Day	40% 10% 23% 18% 7% 2	753
	11th to 20th	Day	38% 14% 22% 16% 7% 3	774
	21st to end	Day	38% 13% 26% 16% 6% 2	845
June	1st to 10th	Day	40% 13% 23% 17% 6% 2	780
	11th to 20th	Day	41% 12% 26% 14% 6% 2	780
	21st to end	Day	34% 12% 27% 15% 8% 4	780
July	1st to 10th	Day	31% 12% 27% 18% 9% 2	770
	11th to 20th	Day	26% 10% 32% 23% 8% 1	768
	21st to end	Day	24% 12% 27% 26% 10% 2	850
August	1st to 10th	Day	27% 10% 25% 24% 11% 2	775
	11th to 20th	Day	28% 10% 29% 21% 11% 1	767
	21st to end	Day	29% 14% 27% 20% 9% 3	858
September	1st to 10th	Day	30% 19% 30% 16% 4 1	580
	11th to 20th	Day	31% 15% 33% 15% 4 1	485
	21st to end	Day	31% 16% 32% 16% 4 2	450
October	1st to 10th	Day	32% 19% 31% 14% 3 1	450
	11th to 20th	Day	34% 16% 26% 18% 6% 1	450
	21st to end	Day	33% 17% 24% 17% 7% 1	486
November	1st to 10th	Day	29% 24% 34% 10% 3	425
	11th to 20th	Day	32% 16% 28% 17% 6% 1	430
	21st to end	Day	35% 16% 27% 18% 4	430
December	1st to 10th	Day	30% 20% 27% 18% 5%	430
	11th to 20th	Day	33% 16% 37% 12% 1 1	430
	21st to end	Day	25% 14% 36% 17% 6% 2	300
January	1st to 10th	Night	27% 17% 32% 17% 7% 1	950
	11th to 20th	Night	23% 19% 32% 20% 6%	950
	21st to end	Night	25% 18% 36% 18% 3	1045
February	1st to 10th	Night	20% 17% 35% 21% 6% 1	950
	11th to 20th	Night	26% 17% 34% 17% 5% 1	908
	21st to end	Night	22% 15% 34% 21% 6% 2	692
March	1st to 10th	Night	26% 20% 29% 19% 5% 1	840
	11th to 20th	Night	24% 17% 30% 23% 7%	753
	21st to end	Night	29% 17% 31% 18% 5% 1	693
April	1st to 10th	Night	29% 16% 29% 19% 7% 1	630
	11th to 20th	Night	29% 16% 30% 17% 7% 2	624
	21st to end	Night	34% 11% 27% 20% 7%	630
May	1st to 10th	Night	36% 9% 23% 23% 8% 1	630
	11th to 20th	Night	34% 9% 26% 21% 9% 2	622
	21st to end	Night	39% 11% 26% 16% 8% 1	682
June	1st to 10th	Night	38% 9% 25% 21% 7%	587
	11th to 20th	Night	38% 9% 22% 20% 9% 1	420
	21st to end	Night	32% 7% 23% 24% 12% 2	420
July	1st to 10th	Night	28% 10% 27% 26% 9%	410
	11th to 20th	Night	26% 9% 35% 23% 6%	577
	21st to end	Night	26% 7% 29% 30% 8%	689
August	1st to 10th	Night	26% 8% 27% 29% 9%	628
	11th to 20th	Night	27% 8% 30% 26% 8%	622
	21st to end	Night	23% 10% 29% 28% 9% 1	693
September	1st to 10th	Night	27% 12% 34% 22% 5%	630
	11th to 20th	Night	31% 14% 31% 19% 5%	630
	21st to end	Night	29% 15% 28% 23% 4 1	630
October	1st to 10th	Night	31% 15% 32% 19% 3 1	730
	11th to 20th	Night	31% 13% 27% 23% 6% 1	960
	21st to end	Night	33% 14% 27% 19% 5%	1042
November	1st to 10th	Night	30% 19% 32% 15% 4	930
	11th to 20th	Night	31% 17% 29% 17% 5% 1	950
	21st to end	Night	33% 21% 28% 15% 3	950
December	1st to 10th	Night	25% 18% 35% 17% 4	950
	11th to 20th	Night	28% 17% 36% 16% 3	950
	21st to end	Night	25% 18% 32% 20% 5% 1	1045

Page generated at 2026-10-26 05:37:48. Version ac07

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