Adds a new Meter to htop that displays your core temperatures. You need the lm_sensors package to use this meter. After applying this patch, you have to call ./autogen.sh before configuring and compiling.

htop-1.0.2-temperature.patch

diff -urN htop-1.0.2-orig/CRT.c htop-1.0.2/CRT.c
--- htop-1.0.2-orig/CRT.c	2013-03-23 14:10:29.500604247 +0100
+++ htop-1.0.2/CRT.c	2013-03-23 14:11:01.916663508 +0100
@@ -59,6 +59,9 @@
    UPTIME,
    BATTERY,
    TASKS_RUNNING,
+   TEMPERATURE_COOL,
+   TEMPERATURE_MEDIUM,
+   TEMPERATURE_HOT,
    SWAP,
    PROCESS,
    PROCESS_SHADOW,
@@ -255,6 +258,9 @@
       CRT_colors[METER_VALUE] = A_BOLD;
       CRT_colors[LED_COLOR] = A_NORMAL;
       CRT_colors[TASKS_RUNNING] = A_BOLD;
+      CRT_colors[TEMPERATURE_COOL] = A_DIM;
+      CRT_colors[TEMPERATURE_MEDIUM] = A_NORMAL;
+      CRT_colors[TEMPERATURE_HOT] = A_BOLD;
       CRT_colors[PROCESS] = A_NORMAL;
       CRT_colors[PROCESS_SHADOW] = A_DIM;
       CRT_colors[PROCESS_TAG] = A_BOLD;
@@ -316,6 +322,9 @@
       CRT_colors[METER_VALUE] = ColorPair(Black,White);
       CRT_colors[LED_COLOR] = ColorPair(Green,White);
       CRT_colors[TASKS_RUNNING] = ColorPair(Green,White);
+      CRT_colors[TEMPERATURE_COOL] = ColorPair(Green,White);
+      CRT_colors[TEMPERATURE_MEDIUM] = ColorPair(Yellow,White);
+      CRT_colors[TEMPERATURE_HOT] = A_BOLD | ColorPair(Red,White);
       CRT_colors[PROCESS] = ColorPair(Black,White);
       CRT_colors[PROCESS_SHADOW] = A_BOLD | ColorPair(Black,White);
       CRT_colors[PROCESS_TAG] = ColorPair(White,Blue);
@@ -377,6 +386,9 @@
       CRT_colors[METER_VALUE] = ColorPair(Black,Black);
       CRT_colors[LED_COLOR] = ColorPair(Green,Black);
       CRT_colors[TASKS_RUNNING] = ColorPair(Green,Black);
+      CRT_colors[TEMPERATURE_COOL] = ColorPair(Green,Black);
+      CRT_colors[TEMPERATURE_MEDIUM] = ColorPair(Yellow,Black);
+      CRT_colors[TEMPERATURE_HOT] = A_BOLD | ColorPair(Red,Black);
       CRT_colors[PROCESS] = ColorPair(Black,Black);
       CRT_colors[PROCESS_SHADOW] = A_BOLD | ColorPair(Black,Black);
       CRT_colors[PROCESS_TAG] = ColorPair(White,Blue);
@@ -438,6 +450,9 @@
       CRT_colors[METER_VALUE] = A_BOLD | ColorPair(Cyan,Blue);
       CRT_colors[LED_COLOR] = ColorPair(Green,Blue);
       CRT_colors[TASKS_RUNNING] = A_BOLD | ColorPair(Green,Blue);
+      CRT_colors[TEMPERATURE_COOL] = ColorPair(Green,Blue);
+      CRT_colors[TEMPERATURE_MEDIUM] = ColorPair(Yellow,Blue);
+      CRT_colors[TEMPERATURE_HOT] = A_BOLD | ColorPair(Red,Blue);
       CRT_colors[PROCESS] = ColorPair(White,Blue);
       CRT_colors[PROCESS_SHADOW] = A_BOLD | ColorPair(Black,Blue);
       CRT_colors[PROCESS_TAG] = A_BOLD | ColorPair(Yellow,Blue);
@@ -499,6 +514,9 @@
       CRT_colors[METER_VALUE] = ColorPair(Green,Black);
       CRT_colors[LED_COLOR] = ColorPair(Green,Black);
       CRT_colors[TASKS_RUNNING] = A_BOLD | ColorPair(Green,Black);
+      CRT_colors[TEMPERATURE_COOL] = ColorPair(Cyan,Black);
+      CRT_colors[TEMPERATURE_MEDIUM] = ColorPair(Yellow,Black);
+      CRT_colors[TEMPERATURE_HOT] = A_BOLD | ColorPair(Red,Black);
       CRT_colors[PROCESS] = ColorPair(Cyan,Black);
       CRT_colors[PROCESS_SHADOW] = A_BOLD | ColorPair(Black,Black);
       CRT_colors[PROCESS_TAG] = A_BOLD | ColorPair(Yellow,Black);
@@ -561,6 +579,9 @@
       CRT_colors[METER_VALUE] = A_BOLD | ColorPair(Cyan,Black);
       CRT_colors[LED_COLOR] = ColorPair(Green,Black);
       CRT_colors[TASKS_RUNNING] = A_BOLD | ColorPair(Green,Black);
+      CRT_colors[TEMPERATURE_COOL] = A_BOLD | ColorPair(Green,Black);
+      CRT_colors[TEMPERATURE_MEDIUM] = A_BOLD | ColorPair(Yellow,Black);
+      CRT_colors[TEMPERATURE_HOT] = A_BOLD | ColorPair(Red,Black);
       CRT_colors[PROCESS] = A_NORMAL;
       CRT_colors[PROCESS_SHADOW] = A_BOLD | ColorPair(Black,Black);
       CRT_colors[PROCESS_TAG] = A_BOLD | ColorPair(Yellow,Black);
diff -urN htop-1.0.2-orig/Header.c htop-1.0.2/Header.c
--- htop-1.0.2-orig/Header.c	2013-03-23 14:10:29.496604239 +0100
+++ htop-1.0.2/Header.c	2013-03-23 14:11:01.916663508 +0100
@@ -12,6 +12,7 @@
 #include "MemoryMeter.h"
 #include "SwapMeter.h"
 #include "TasksMeter.h"
+#include "TemperatureMeter.h"
 #include "LoadAverageMeter.h"
 #include "UptimeMeter.h"
 #include "BatteryMeter.h"
@@ -151,6 +152,7 @@
    Vector_add(this->leftMeters, Meter_new(this->pl, 0, &MemoryMeter));
    Vector_add(this->leftMeters, Meter_new(this->pl, 0, &SwapMeter));
    Vector_add(this->rightMeters, Meter_new(this->pl, 0, &TasksMeter));
+//    Vector_add(this->rightMeters, Meter_new(this->pl, 0, &TemperatureMeter));
    Vector_add(this->rightMeters, Meter_new(this->pl, 0, &LoadAverageMeter));
    Vector_add(this->rightMeters, Meter_new(this->pl, 0, &UptimeMeter));
 }
diff -urN htop-1.0.2-orig/Makefile.am htop-1.0.2/Makefile.am
--- htop-1.0.2-orig/Makefile.am	2013-03-23 14:10:29.499604245 +0100
+++ htop-1.0.2/Makefile.am	2013-03-23 14:12:23.748812438 +0100
@@ -20,7 +20,7 @@
 BatteryMeter.c Process.c ProcessList.c RichString.c ScreenManager.c Settings.c \
 IOPriorityPanel.c SignalsPanel.c String.c SwapMeter.c TasksMeter.c TraceScreen.c \
 UptimeMeter.c UsersTable.c Vector.c AvailableColumnsPanel.c AffinityPanel.c \
-HostnameMeter.c OpenFilesScreen.c Affinity.c IOPriority.c
+HostnameMeter.c OpenFilesScreen.c Affinity.c IOPriority.c TemperatureMeter.c

 myhtopheaders = AvailableColumnsPanel.h AvailableMetersPanel.h \
 CategoriesPanel.h CheckItem.h ClockMeter.h ColorsPanel.h ColumnsPanel.h \
@@ -29,7 +29,7 @@
 BatteryMeter.h Meter.h MetersPanel.h Object.h Panel.h ProcessList.h RichString.h \
 ScreenManager.h Settings.h SignalsPanel.h String.h \
 SwapMeter.h TasksMeter.h TraceScreen.h UptimeMeter.h UsersTable.h Vector.h \
-Process.h AffinityPanel.h HostnameMeter.h OpenFilesScreen.h Affinity.h IOPriority.h
+Process.h AffinityPanel.h HostnameMeter.h OpenFilesScreen.h Affinity.h IOPriority.h TemperatureMeter.h

 SUFFIXES = .h

diff -urN htop-1.0.2-orig/Meter.c htop-1.0.2/Meter.c
--- htop-1.0.2-orig/Meter.c	2013-03-23 14:10:29.499604245 +0100
+++ htop-1.0.2/Meter.c	2013-03-23 14:11:01.917663509 +0100
@@ -11,6 +11,7 @@
 #include "MemoryMeter.h"
 #include "SwapMeter.h"
 #include "TasksMeter.h"
+#include "TemperatureMeter.h"
 #include "LoadAverageMeter.h"
 #include "UptimeMeter.h"
 #include "BatteryMeter.h"
@@ -126,6 +127,7 @@
    &MemoryMeter,
    &SwapMeter,
    &TasksMeter,
+   &TemperatureMeter,
    &UptimeMeter,
    &BatteryMeter,
    &HostnameMeter,
diff -urN htop-1.0.2-orig/TemperatureMeter.c htop-1.0.2/TemperatureMeter.c
--- htop-1.0.2-orig/TemperatureMeter.c	1970-01-01 01:00:00.000000000 +0100
+++ htop-1.0.2/TemperatureMeter.c	2013-03-23 14:11:01.917663509 +0100
@@ -0,0 +1,97 @@
+/*
+htop - TemperatureMeter.c
+(C) 2013 Ralf Stemmer
+Released under the GNU GPL, see the COPYING file
+in the source distribution for its full text.
+*/
+
+#include "TemperatureMeter.h"
+
+#include "ProcessList.h"
+#include "CRT.h"
+
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <limits.h>
+
+/*{
+#include "Meter.h"
+}*/
+
+int TemperatureMeter_attributes[] = {
+   TEMPERATURE_COOL,
+   TEMPERATURE_MEDIUM,
+   TEMPERATURE_HOT,
+};
+
+static void TemperatureMeter_setValues(Meter* this, char* buffer, int len) {
+   ProcessList* pl = this->pl;
+   this->total = pl->totalTasks;
+   this->values[0] = pl->runningTasks;
+   snprintf(buffer, len, "%d/%d", (int) this->values[0], (int) this->total);
+}
+
+static void TemperatureMeter_display(Object* cast, RichString* out) {
+   FILE *p;
+   p = popen("sensors", "r");
+   if(p == NULL) return 1;
+
+   int textColor   = CRT_colors[METER_TEXT];
+   int coolColor   = CRT_colors[TEMPERATURE_COOL];
+   int mediumColor = CRT_colors[TEMPERATURE_MEDIUM];
+   int hotColor    = CRT_colors[TEMPERATURE_HOT];
+
+   size_t read, len;
+   char *line = NULL;
+   char *entry = NULL;
+   char *tstart = NULL, *tend = NULL;
+   int  temperature;
+   while ((read = getline(&line, &len, p)) != -1) {
+      // contains this line a core-temperature?
+      entry = strstr(line, "Core ");
+      if (entry == NULL) continue;
+
+      // find the begin of the temperature value
+      tstart = strchr(entry, '+'); // no negative temperatures expected :)
+      if (tstart == NULL) continue;
+      tstart++; // jump over the '+'
+
+      // find the end of the temperature. Remember, it can be above 99°C ;)
+      tend = strchr(tstart, '.'); // just the integer
+      if (tend == NULL) continue;
+
+      // convert the string into an integer, this is necessary for further steps
+      temperature = strtol(tstart, &tend, 10);
+      if (temperature == LONG_MAX || temperature == LONG_MIN) continue;
+      if (tstart == tend) continue;
+
+      // choose the color for the temperature
+      int tempColor;
+      if      (temperature < 80)                      tempColor = coolColor;
+      else if (temperature >= 80 && temperature < 90) tempColor = mediumColor;
+      else                                            tempColor = hotColor;
+
+      // output the temperature
+      char buffer[20];
+      sprintf(buffer, "%d", temperature);
+      RichString_append(out, tempColor, buffer);
+      RichString_append(out, textColor, "°C ");
+   }
+
+   free(line);
+   pclose(p);
+}
+
+MeterType TemperatureMeter = {
+   .setValues = TemperatureMeter_setValues,
+   .display = TemperatureMeter_display,
+   .mode = TEXT_METERMODE,
+   .items = 1,
+   .total = 100.0,
+   .attributes = TemperatureMeter_attributes,
+   .name = "Temperature",
+   .uiName = "Temperature Sensors",
+   .caption = "Temperature: "
+};

I have added a fork which updates this to work with htop 1.0.3.

I want to adapt this to make it display temperatures, but for orange pi pc, the way i can see temperatures now is by "cat /path/to/file" would it be possible ?
if yes, can you help?